Framing pictures: the role of knowledge in automatized encoding and memory for gist. In general, frame theories are theories about the representation and use of knowledge for pattern recognition. In the present article, the general properties of frame theories are discussed with regard to their implications for psychological processes, and an experiment is presented which tests whether this approach yields viable predictions about the manner in which people comprehend and remember pictures of real-world scenes. Normative ratings were used to construct six target pictures, each of which contained both expected and unexpected objects. Eye movements were then recorded as subjects who anticipated a difficult recognition test viewed the targets for 30 sec each. Then, the subjects were asked to discriminate the target pictures from distractors in which either expected or unexpected objects had been changed. One consequence of the embeddedness of frame systems is that global frames may function as "semantic pattern detectors," so that the perceptual knowledge in them could be used for relatively automatic pattern recognition and comprehension. Thus, subjects might be able to identify expected objects by using automatized encoding procedures that operate on global physical features. In contrast, identification of unexpected objects (i.e., objects not represented in the currently active frame) should generally require more analysis of local visual details. These hypotheses were confirmed with the fixation duration data: First fixations to the unexpected objects were approximately twice as long as first fixations to the expected objects. On the recognition test, subjects generally noticed only the changes that had been made to the unexpected objects, despite the fact that the proportions of correct rejections were made conditional on whether the target objects had been fixated. These data are again consistent with the idea that local visual details of objects represented in the frame are not neccesary for identification and are thus not generally encoded. Further, since subjects usually did not notice when expected objects were deleted or replaced with different expected objects, it was concluded that if two events instantiate the same frame, they may often be indistinguishable, as long as any differences between them are represented as arguments in the frame. Thus, for the most part, the only information about an event that is episodically "tagged" is information which distinguishes that particular event from others of the same general class. The data reinforce the utility of a frame theory approach to perception and memory.


Orthography and familiarity effects in word processing. Both orthographic regularity and visual familiarity have been implicated as contributors to the efficiency of processing visually presented words. Our studies sought to determine which of the internal codes representing words in the nervous system are facilitated by these two variables. To do this, sets of letter strings in which orthography and familiarity were factorially combined were used as the basis for physical, phonetic, semantic, and lexical judgments. The data indicated consistent effects of orthography on the activation of all codes. These effects were seen in same-different matching and in judgments of stimulus orientation, which are based on visual codes; in judgments of pronounceability based on phonetic codes; in judgments of meaningfulness based on semantic codes; and in lexical decisions, which are based on phonetic and semantic codes together. Familiarity, on the other hand, had a clear influence on the activation of semantic codes and to a lesser extent affected phonetic codes. Despite previous positive results found in matching letter strings, however, no influence of familiarity occurred in judgments based on visual codes once evidence for criterion shifting was eliminated. Our negative results included direct tests of facilitation in matching acronyms (e.g., FBI) and in matching both regular and irregular strings familiarized by specific training. It now appears that earlier findings of visual familiarity effects may be attributed to response biases resulting from the activation of higher level codes sensitive to familiarity, and to the use of small sets of training stimuli that allowed subjects to induce orthographic-like rules. The results obtained so far with our methods seem to reconcile an inconsistent literature by showing that speeded decisions based on visual codes are most strongly influenced by rule-governed processing mechanisms sensitive to orthographic structure, whereas decisions based on phonetic and semantic codes are affected about equally by rule-governed mechanisms and by stimulus-specific mechanisms sensitive to familiarity. This conclusion may lead to changes in notions of how effective various kinds of visual training are likely to be at different stages in the acquisition of reading skill.


Judgment of contingency in depressed and nondepressed students: sadder but wiser? How are humans' subjective judgments of contingencies related to objective contingencies? Work in social psychology and human contingency learning predicts that the greater the frequency of desired outcomes, the greater people's judgments of contingency will be. Second, the learned helplessness theory of depression provides both a strong and a weak prediction concerning the linkage between subjective and objective contingencies. According to the strong prediction, depressed individuals should underestimate the degree of contingency between their responses and outcomes relative to the objective degree of contingency. According to the weak prediction, depressed individuals merely should judge that there is a smaller degree of contingency between their responses and outcomes than nondepressed individuals should. In addition, the present investigation deduced a new strong prediction from the helplessness theory: Nondepressed individuals should overestimate the degree of contingency  between their responses and outcomes relative to the objective degree of contingency. In the experiments, depressed and nondepressed students were present with one of a series of problems varying in the actual degree of contingency. In each problem, subjects estimated the degree of contingency between their responses (pressing or not pressing a button) and an environmental outcome (onset of a green light). Performance on a behavioral task and estimates of the conditional probability of green light onset associated with the two response alternatives provided additional measures for assessing beliefs about contingencies. Depressed students' judgments of contingency were surprisingly accurate in all four experiments. Nondepressed students, on the other hand, overestimated the degree of contingency between their responses and outcomes when noncontingent outcomes were frequent and/or desired and underestimated the degree of contingency when contingent outcomes were undesired. Thus, predictions derived from social psychology concerning the linkage between subjective and objective contingencies were confirmed for nondepressed students but not for depressed students. Further, the predictions of helplessness theory received, at best, minimal support. The learned helplessness and self-serving motivational bias hypotheses are evaluated as explanations of the results. In addition, parallels are drawn between the present results and phenomena in cognitive psychology, social psychology, and animal learning. Finally, implications for cognitive illusions in normal people, appetitive helplessness, judgment of contingency between stimuli, and learning theory are discussed.


On measuring fuzziness: a comment on "A fuzzy set approach to modifiers and vagueness in natural language". Hersh and Caramazza's application of fuzzy set theory to vagueness in natural language is criticized for including in their measures of fuzziness response variability due to experimental and statistical procedures.


Encoding and use of detail information in picture recognition. Subjects participated in a yes/no picture recognition experiment in which exposure time varied from 50 to 1,000 msec at the time of initial study. Following each study trial, half of the subjects, the detail at study and test (ST) group, reported whether they had observed a detail in the picture that they thought might help in subsequent recognition. The other half of the subjects, the detail at test only (T) group, did not attempt to name details during study. All of the subjects reported at the time of each test picture whether they were basing their yes/no recognition response on a specific detail in the picture or on the picture's general familiarity. The data provided strong support for a model which assumed that (a) there is a constant probability of encoding a detail during each successive unit of time at study and (b) a detail is named at test either if it was encoded at study or with some bias probability. ST subjects showed superior recognition memory performance relative to T subjects. Within the context of the aforementioned model, this superiority stems from two sources: ST subjects encode details at a faster rate than do T subjects and an encoded detail provided a better discriminative feature for ST subjects.


Recognition memory for typical and unusual faces. In four studies, recognition memory for faces rated as similar to a prototype was found to be inferior to memory for faces rated as unusual in appearance. This result was obtained under both incidental and intentional learning conditions, at presentation rates ranging from 3 to 15 sec, and with retention intervals from 3 to 24 hr. A fifth experiment established interitem similarity as the structural basis of this typicality effect in recognition memory. Difficulties in interpreting the findings in terms of some current models for classification learning, depth of processing models, or present models of the word frequency effect are discussed.


Fact and fantasy: the roles of accuracy and variability in confusing imaginations with perceptual experiences. In Experiment 1, pictures were presented to subjects two, five, or eight times, and subjects were asked to imagine each pciture two, five, or eight times. Subsequently, subjects estimated the number of times each picture had been presented. Their estimates of the frequency of these external events were influenced by imagination trials; this effect was greater for good imagers than for poor imagers. Experiment 2 involved a similar design in which subjects were asked either to imagine the same referent for a word or to imagine a different referent for a word on successive imagination trials. Consistency (same referent) did not increase the influence of imaginations on immediate judgments of external frequency. Thus, the results of Experiment 1 were attributed to the greater accuracy (as opposed to greater consistency) of good imagers' internal generations of the stimuli. Furthermore, variation (imagining different referents), like greater accuracy, increased the effects of imagination trials on immediate but not on delayed judgments of frequency. Possible mechanisms underlying these effects are discussed. In general, the two studies show that qualitative characteristics of completely covert generations influence their impact on estimates of the frequency of external events.


Transfer of stimulus differentiation and perceptual selection rules. Three experiments examined the conditions under which transfer of stimulus differentiation occurs. Two experiments involved transfer in paired associate lists having identical stimuli and re-paired response terms compared with lists having different stimuli. In one experiment, transfer was determined for lists of three-word stimuli in which various elements were shared among the stimuli. The pattern of redundancy was such that the spatial position of a discriminative element was either consistent or not consistent in different items, or there was no discriminative element. Transfer of differentiation was obtained only when position was constant. In the second experiment, stimuli were single words and were either unrelated, rhymed, or were instances of common concepts. No evidence of transfer of differentiation was obtained with either rhymes or concepts. In the third experiment, subjects learned pairs in which the stimuli were single letters; then subjects transferred to a list in which either rhyming or unrelated stimuli began with the same letters. Transfer was not differential.


Visual and verbal memory for objects and their spatial locations. Four experiments assessed the role of verbal and visual processing in memory for aspects of a simulated, real-world spatial display. Subjects viewed a three-dimensional model of a city with 16 bulidings that were placed on the display. The buildings were represented on the model with or without an accompanying name label on each buliding. After studying the display, subjects were tested on recall and recognition of the building names, picture recognition of the buildings, and spatial memory for where the bulidings had been located. Overall picture recognition accuracy was low, and the presence of a name label on each building significantly reduced picture recognition accuracy but improved relocation accuracy. Spatial location information was not encoded independently of verbal and visual identity information. However, location information was more accurately retained with memory for verbal than visual aspects of the stimuli. The results are discussed in terms of the theoretical importance of differentiating memory for the identity of visual stimuli from descriptive memory for their physical characteristics in "visual memory" research.


Transfer of persistence across behaviors. Two experiments tested the applicability to human beings of findings with animals that the number of performances required for the reinforcement of one behavior affects the subsequent effort expended in other instrumental behaviors. In the first experiment, adult depressed psychiatric patients worked on a sorting task for the approval of a staff psychologist. The time spent and the work completed were increased by prior approval from a ward attendant for each completion of several custodial tasks, as compared to the ward attendant's approval for each completion of a single task or a no-pretreatment control condition. In the second experiment, preadolescent learning-disabled students who were required to read and spell correctly a greater number of words per reward token later spent more time and completed more work for reward tokens in mathematics, and handwriting. Two alternative interpretations of these results are evaluated: (a) The degree of accustomed effort per reinforcer becomes a learned component of behavior, or (b) high effort increases the habituation of frustration-produced disruptive responses. The results suggest that individual differences in general persistence may arise, in part, from an accumulation of effort training in the natural environment.


Abstraction of prototypical information by adults and 10-month-old infants. The primary purpose of this study was to investigate whether preverbal infants, when presented with exemplars of an artificially constructed category, would abstract a prototypical representation of the category, and if so, whether this representation was formed by either "counting" or "averaging" the features that were varying among category members. Two experiments are reported. In Experiment 1, a set of stimuli was developed and tested for which it was demonstrated that adult subjects would readily abstruct either a modal or an average prototypical representation. The type of representation abstracted was found to be dependent on the discriminability of the feature values. In Experiment 2, 10-mo.-old infants were tested using a habituation paradigm with the stimuli developed in the first experiment. The results of this study indicated that the infants were also able to abstract the featural information that was varying among the exemplars of the category, and the infants formed an internal represenatation of the category by averaging feature values. Thus, the results clearly imply that infants are able to constructively process visual information and hence take a more active role in category formation than had been previously believed.


Measuring the size of mental images.

Measuring the size of mental images. Mental images seem to have a size; the experimental problem was to map that image size onto a scale of physical measurement. To this end, two experiments were conducted to measure the size of mental images in degrees of visual angle. In Experiment 1, college students employed light pointers to indicate the horizontal extent of projected mental images of words (the letter string, not the referent). Imagined words covered about 1.0 degress of visual angle per letter. In Experiment 2, a more objective eye-movement response was used to measure the visual angle size of imagined letter strings. Visual angle of eye movement was found to increase regularly as the letter distance between the fixation point and a probed letter position increased. Each letter occupied about 2.5 degrees of visual angle for the four-letter strings in the control/default size condition. Possible relations between eye movements and images are discussed.


Interaction of stimulus size and retinal eccentricity in metacontrast masking. Metacontrast masking occurs both at the fovea and in the retinal periphery; foveally, the smallest stimulus elicited the strongest masking, whereas peripherally the reverse was the case. An analysis of variance showed a significant size effect, eccentricity effect, and size-eccentricity interaction. As stimulus size increased, the stimulus onset asynchrony of maximum masking shifted to greater values. Both foveal metacontrast and peak shifts contradicted predictions made by the hypothesis that metacontrast is mediated by an interaction of sustained and transient channels in the visual system. The data are consistent, however, with a lateral inhibitory model of metacontrast masking and stimulus coding.


Similarity effects in backward recognition masking. Auditory backward recognition masking refers to the ability of a masking sound to terminate further perceptual resolution of a test sound presented slightly earlier in time. The present experiments were conducted to determine whether mask/test tone similarity effects in backward recognition masking could be reliably demonstrated. Although similarity effects were found in Experiments 1 and 2, only about 60% of the subjects demonstrated these effects. Experiment 3 was designed to isolate which stage of information processing is responsible for similarity effects. It was hypothesized that similarity effects are due to mask interference with the synthesized auditory memory of the test tone rather than to selective overwriting of a preperceptual auditory store: previous research has shown that interference in synthesized auditory memory depends on the similarity of the interfering stimulus to the items held in memory. By independently varying the backward masking interval and the interfering effect of the mask on the test tone memory, it was possible to demonstrate that similarity effects are indeed caused by mask interference in synthesized memory. The implications of these results are considered in the framework of auditory and visual masking.


Categories and context in the perception of isolated steady-state vowels. The noncategorical perception of isolated vowels has been attributed to the availability of auditory memory in discrimination. In our first experiment, using vowels from an /i/-/I/epsilon) continuum in a same-different (AX) task and comparing the results with predictions derived from a separate identification test, we demonstrated that vowels are perceived more nearly categorically if auditory memory is degraded by extending the interstimulus interval and/or filling it with irrelevant vowel sounds. In a second experiment, we used a similar paradigm, but in addition to presenting a separate identification test, we elicited labeling responses to the AX pairs used in the discrimination task. We found that AX labeling responses predicted discrimination performance quite well, regardless of whether auditory memory was available, whereas the predictions from the separate identification test were more poorly matched by the obtained data. The AX labeling reponses showed large contrast effects (both proactive and retroactive) that were greatly reduced when auditory memory was interfered with. We conclude from the presence of these contrast effects that vowels are not perceived categorically (that is, absolutely). However, it seems that by taking the effects of context into account properly, discrimination performance can be quite accurately predicted from labeling data, suggesting that vowel discrimination, like consonant discrimination, may be mediated by phonetic labels.


Mental travel: some reservations.

Mental travel: some reservations. Two experiments were conducted to assess the extent of potential experimental demand characteristics inherent in the image-scanning paradigm. The results of the first "mental travel" experiment that pitted verbal versus imagery coding showed that (a) the positive correlation between physical distance and reaction time was replicated, and (b) when given a choice, subjects' reaction times varied as a function of verbal codes rather than imagery. To isolate the effects due to demand constraints from those produced by mode dominance, a nonexperiment in which subjects received only a description of the image-scanning procedure was conducted. Results demonstrated that subjects were capable of predicting the reaction time results for both verbal and imagery codes. The presence of experimental demand in the image-scanning paradigm necessitates caution when structural interpretations of visual images are considered.


Auditory phase and frequency discrimination: a comparison of nine procedures. Two auditory discrimination tasks were thoroughly investigated: discrimination of frequency differences from a sinusoidal signal of 200 Hz and discrimination of differences in relative phase of mixed sinusoids of 200 Hz and 400 Hz. For each task psychometric functions were constructed for three observers, using nine different psychophysical measurement procedures. These procedures included yes-no, two-interval forced-choice, and various fixed- and variable-standard designs that investigators have used in recent years. The data showed wide ranges of apparent sensitivity. For frequency discrimination, models derived from signal detection theory for each psychophysical procedure seem to account for the performance differences. For phase discrimination the models do not account for the data. We conclude that for some discriminative continua the assumptions of signal detection theory are appropriate, and underlying sensitivity may be derived from raw data by appropriate transformations. For other continua the models of signal detection theory are probably inappropriate; we speculate that phase might be discriminable only on the basis of comparison or change and suggest some tests of our hypothesis.


Choice reaction times for temporal numerosity. Subjects watched rapidly presented visual sequences of two events until they decided which event was the more frequent. Accuracy was reduced both by increased rates of presentation and by the addition of more inconclusive information to the initial portion of the sequence. Response latencies were longest when there was no objective numerosity inbalance, and they decreased, for both correct responses and errors, when discrimination was relatively easy. The patterns of decision latencies for individual subjects could be represented on a continuum defined by the sensitivity of the latencies to the rate of event presentation and to the objective inbalance between the two events. The discussion points out formal and empirical similarities between sequential numerosity judgments and choice reaction times. The present results are discussed within the framework of a first-passage time model, to be developed formally in a subsequent paper.


Depth of nontarget processing in an attention task. Two studies examined the effect of the sensory discriminability of targets from nontargets on depth of nontarget processing. Subjects shadowed target words that were binaurally presented with coincident nontarget words. Targets and nontargets were spoken in the same male voice under low sensory discriminability and in male and female voices, respectively under high sensory discriminability. Across the two studies, depth of nontarget processing was assessed in three ways: extent to which shadowing accuracy was disrupted by a semantic overlap between targets and nontargets, expenditure of capacity (reaction time to subsidiary light signals), and nontarget recall. All three possible measures of depth of nontarget processing decreased as sensory discriminability increased. The data support the assumption of multiple-loci theories of attention that nontargets can be perceptually inhibited; they contraindicate the assumption of late-selection theories that perceptual processing is automatic and irrepressible.


Effects of S-R mapping and response modality on performance in a Stroop Task. Forty subjects performed a choice reaction time task in which the stimulus was the word Red or Green printed in either red or green ink. Subjects responded verbally in one block of trials and by key pressing in another block. For one group, ink color was the relevant cue, and for another group, the word was the relevant cue. Half of the subjects in each group were instructed to make the response that corresponded to the relevant cue (compatible S-R [stimulus-response] mapping); the other half were instructed to make the response that did not correspond (incompatible S-R mapping). In general, subjects who performed under compatible S-R mapping instructions reacted faster when the irrelevant cue corresponded to the response than when it did not. In contrast, subjects show performed under incompatible S-R mapping instructions reacted faster when there was a lack of correspondence between the irrelevant cue and the response than when there was correspondence. Results were consistent with a notion of logical recoding; that is, that instructing subjects to recode the relevant cue into the alternate color may have caused them to recode the irrelevant cue in the same logical manner. Results might also be interpreted to suggest that the Stroop effect is related to congruence between the relevant and the irrelevant cues rather than to correspondence between the irrelevant cue and the response.


Spare the rod and spoil the icon.

Spare the rod and spoil the icon. Short-term visual storage was investigated with a successive field paradigm, so that correct performance depended upon combining visual information from two targets that were never on simultaneously. In the first two experiments, the stimuli consisted of two slides, each containing a 10' red dot on a gray surround, and separated by an interstimulus interval (ISI) from 20 to 400 msec. Subjects had to determine if the dots were vertically or horizontally aligned. In Experiment 1, the stimuli had either no contrast for the rods or no luminance contrast for the cones or high contrast. At short ISIs the cone contrast determined performance, whereas at long ISIs the rod contrast determined performance. In fact, when the dots were invisible to the rods, the task was impossible for long ISIs. In Experiment 2, performance was compared for zero log rod contrast and for small departures from zero. Even a small departure from zero log rod contrast resulted in above-chance performance. In Experiment 3, the stimuli were luminous rectangles and the task was to decide whether or not a 4' spatial gap was present between the two successively presented rectangles. Wavelength, luminance, and ISI were varied under both photopic and scotopic adapting conditions. The result was that the rods performed the task for ISIs of 150 msec or longer under scotopic conditions and under the photopic conditions that we were able to test. The results of the experiments taken together are consistent with the hypothesis that the cone icon is short, whereas the rod icon is robust and long lasting.


Iconic storage in the two hemispheres.

Iconic storage in the two hemispheres. Three experiments have tested for the existence of laterality effects in iconic storage by employing a Sperling partial-report paradigm and lateralized presentations of alphabetical or pattern material. Even though an overall laterality effect was found in favor of the right visual field for the alphabetical material and in favor of the left visual field for the pattern material, the amount and time decay of partial-report advantage was similar in the two visual fields. These results indicate that hemispheric asymmetries occur beyond the iconic stage of visual information processing.


Coding left and right.

Coding left and right. The present study compared the processing of direction for up and down arrows and for left and right arrows in visual displays. Experiment 1 demonstrated that it is more difficult to deal with left and right than with up and down when the two directions must be discriminated but not when they must simply be oriented to. Experiments 2 and 3 showed that telling left from right is harder regardless of whether the responses are manual or verbal. Experiment 4 showed that left-right discriminations take longer than up-down discriminations for judgments of position as well as direction. In Experiment 5 it was found that position information can intrude on direction judgments both within a dimension (e.g., a left arrow to the left of fixation is judged faster than a left arrow to the right of fixation) and across dimensions (e.g., judging vertically positioned left and right arrows is more difficult than judging horizontally positioned left and right arrows). There was indirect evidence in these experiments that although the spatial codes for up and down are symmetrical, the codes for left and right may be less so; this in turn could account for the greater difficulty of discriminating left from right.


Visual classes and natural categories in the pigeon. After being trained on an oak leaf pattern, pigeons responded to other oak leaf patterns but not to leaf patterns of other species. Thus, graphic variation among the instances of a species is "transparent" to the visual system. At this taxonomic level, concept formation is spontaneous rather than inductive. It is argued that such immediate generalization may be critical to the survival of the organism.


Rotation of objects in pictures viewed at an angle: evidence for different properties of two types of pictorial space. As an observer views a picture from different viewing angles, objects in the picture appear to change orientation relative to the observer, but some objects change orientation more than others. This difference in rotation for different objects is called the differential rotation effect. The differential rotation is not, however, accompanied by corresponding changes in the perception of the spatial layout of objects in the picture. This lack of correspondence between the perception of rotation and the perception of spatial layout is a result of the fact that the information on a picture's surface defines two kinds of pictorial space with different properties. Rotation is perceived in terms of the pictorial space outside the picture, and spatial layout is perceived in terms of the pictorial space inside the picture.


Figural relationship effects and mechanisms of visual masking. In each of three visual pattern masking experiments, four curved letters (C, O, Q, S) and four angular letters (E, I, L, T) served as targets preceded or followed by either a curved mask (Q,S, and C superimposed) or an angular mask (T and E superimposed). With a dark fixation and interstimulus interval field and target-mask engergies that produce clearly identifiable targets, the following figural relationship effects were found. At stimulus onset asynchronies (SOAs) from 0 to 20 msec (in both forward and backward masking), target recognition was more accurate when targets and masks overlapped exactly (same features) than when they did not (different features). At backward masking SOAs beyond 20 msec, this pattern was reversed, but there was no such reversal in forward masking. Such results indicate that the dominant mechanism of masking at SOAs from 0 to 20 msec is luminance summation over time but that luminance summation gives way to feature-specific interference at longer SOAs. Subsequent experiments demonstrate that (a) luminance summation effects are reduced by using bright fixation and interstimulus fields and (b) feature-specific interference is eliminated by using low-energy (and, therefore, less than perfectly identifiable) targets and masks.


Divided attention: the whole is more than the sum of its parts. A divided attention situation is more than the sum of its component single tasks. Emergent aspects of the whole situation must also be considered. Three examples illustrate this. (a) When several complex stimuli (e.g., letters) are identified at once, their perceived components or features must be appropriately bundled together. Otherwise, components of two different stimuli may appear combined. This (emergent) problem is shown to depend on attention to multiple stimuli, not simply their presentation. (b) In the psychological refractory period (PRP) situation, especial difficulties arise when stimulus-response mappings are different for first and second reactions. It appears that for each reaction there is some (emergent) uncertainty over which mapping to use. This is only one of many possible emergent processes in the PRP situation. (c) When the two hands perform different actions (internally programmed sequences of taps), there is some tendency for each hand to carry out the action assigned to the other. This again is only a small part of the (emergent) problem of motor coordination. Thus the simple idea of competition for limited resources captures only a part of the problem of divided attention. Performance under divided attention will reflect an interaction between resource limitation, single task processes, and emergent aspects of the whole situation.


On the coordination of two-handed movements. In a set of three experiments, we show that after an auditory "go" signal, subjects simultaneously initiate and terminate two-handed movements to targets of widely disparate difficulty. This is the case when the movements required are (a) lateral and away from the midline of the body (Experiment 1), (b) toward the midline of the body (Experiment 2), and (c) in the forward direction away from the body midline (Experiment 3). Kinematic data obtained from high-speed cinematography (200 frames/sec) point to a tight coordinative coupling between the two hands. Although the hands move at entirely different speeds to different points in space, times to peak velocity and acceleration are almost perfectly synchronous. We believe that the brain produces simultaneity of action as the optimal solution for the two-handed task by organizing functional groupings of muscles (coordinative structures) that are constrained to act as a single unit.


Contextual facilitation in a letter search task depends on how the prime is processed. In a variety of situations it has been observed that the processing of a verbal stimulus is facilitated when it is preceded by an associated word. This article is concerned with determining whether such facilitation occurs automatically upon prime presentation or whether facilitation depends on the manner of processing the prime. Experiment 1 demonstrated that a letter search in a target word was facilitated when the target was preceded by either an identical or semantically associated word. If, however, a letter search was required in the prime as well as in the target (Experiment 2), the relative advantage enjoyed by targets preceded by identical-word primes disappeared. Experiment 3 replicated this loss of facilitation using semantically associated word pairs. Contextual facilitation thus appears to depend upon the mode of analysis of the prime. If the prime is analyzed as a meaningful unit, facilitation occurs. If, however, it is subjected to a more discrete, letter-by-letter analysis, the priming effect vanishes.


Semantic context and word frequency effects in visual word recognition. Semantic context and word frequency factors exert a strong influence on the time that it takes subjects to recognize words. Some of the explanations that have been offered for the effects of the two factors suggest that context and frequency should interact, and other explanations imply additivity. In a recent study, Schuberth and Eimas reported that context and frequency effects added to determine their subjects' reaction times in a lexical decision (word vs. nonword) task. The present experiment reexamines this question with improved procedures. The data show that context and frequency do interact, with a semantic context facilitating the processing of low-frequency words more than high-frequency words.


Visual persistence and code selection in short-term memory for letters. Four experiments were conducted to examine temporal changes in visual and name codes and the relationship between them. Unlike earlier studies, the design included (a) several levels of visual similarity in addition to the conventional same case and different case conditions and (b) physical- as well as name-match tasks to provide direct evidence about subjects' retention of form information. The main results were as follows: First, the presence of multiple typefonts in the stimulus set does not eliminate convergence between the reaction time functions for the physical- and name-match conditions in a name-match task. Second, inclusion of a physical-match task, requiring subjects to retain form information, does not necessarily eliminate convergence in a primary, name-match task. When the secondary task does reduce convergence, however, the results suggest that it does this through its effect on the name-match function rather than on the physical-match function. Third, apart from difficulties with within-cluster typefont combinations, particularly at long interstimulus intervals, subjects can generally retain and use reliable information about letter form over the ISI range (.5--4.0 sec) used in the experiments. The results were thought to be consistent with the conclusion that convergence results from a combination of (a) a nonoptional decrease in the accessibility of the visual code as a function of increasing ISI and (b) an optional increase in the accessibility of the name code. Under ISI conditions at least, convergence cannot be attributed to either generation of a visual code of the alternative form of the target letter or to the absence of relevant form information.


A model of unidimensional perceptual matching. Faster same than different judgments typically are obtained when two letters are compared. When two tones that might differ only on frequency are compared, however, same judgments typically are slower than different judgments. A uniprocessor, unidimensional model, based on Krueger's noisy-operator theory, was fitted satisfactorily to data from four published studies of tone comparison. The model predicts faster response time on different judgments because of heterogeneity of difference. Because the second tone in a pair typically may be either higher or lower in frequency than the first, there will be a greater variety of perceived difference counts on different pairs than on same pairs. As a result, a large difference count will be decisive and will lead to an immediate "different" response, because it can be produced only by a different pair, whereas a small difference count will not be so decisive because it can be produced by either a same or a different pair. Consequently, there generally will be more rechecking on same than different pairs, and thus longer RT on same pairs.


Perception of wheel-generated motions.

Perception of wheel-generated motions. Data are presented on an old and familiar Gestalt demonstration--perceiving wheel-generated motions--in which the perceived motions of a rolling wheel are shown not to be obviously derived from the motions of the parts. The history of study of this phenomenon is presented, and contradictions in the literature are noted. The focus for experimentation is on the contrasting approaches found in Johansson's perceptual vector analysis and Wallach's arguments for the priority of object-relative displacement in the extraction of invariants. Johansson's approach asserts that common vectors are extracted from moving events first, whereas Wallach asserts that the motion of objects relative to each other is first. These two approaches yield different predictions about what ought to be seen when different configurations are viewed in rotation. In five experiments viewers rated how wheellike the movement of various point-light systems attached to a rolling wheel appeared to be. Results support Wallach's views over Johansson's. Viewer judgments of goodness in wheellike motion correspond highly with a mathematical description of the parameters of cycloidal motion for the geometric center of any system of lights on a rolling wheel. This specification can be made only after the extraction of object-relative displacement information. Number of lights and order of symmetry influence viewer judgments to a much lesser degree, and placement of a light at the wheel's center matters not at all.


Variable criterion analysis of brightness effects in simple reaction time. Using light onset as the stimulus in simple reaction time (SRT), the effect of stimulus intensity was studied in both between-subjects and within-subjects experimental designs. There was a strong intensity effect in both conditions but no significant interaction between the effect of stimulus intensity and the type of design. This differs from previous results with auditory stimuli where such an interaction has been demonstrated. When the criterion parameters of variable criterion theory were evaluated directly, the only significant effect was greater criterion variability in the between-subjects condition. Theoretical functions describing the growth of sensory strength for each intensity had different starting points and were largely parallel, showing only late temporal divergence. This provides an explanation of the rarity, in the SRT literature, of interactions between visual intensity and criterion variables. Correlations illustrating the relations between reaction time (RT) measures and theoretical criterion parameters are presented. Absence of the predicted relation between intensity and RT variability is evidence against theories relating RT to impulse rate treated as a Poisson process.


On the inhibitory nature of binocular rivalry suppression. During binocular rivalry the average duration of a suppression phase depends on the stimulus strength (e.g., contrast) of the input to the suppressed eye. To determine if a similar relationship exists between stimulus strength and the inhibitory effect of suppression on test probe detectability, a series of experiments was performed. Using two-alternative forced-choice procedures, increment detection thresholds were measured during phases of dominance and suppression. Results from three trained observers show that detection performance is significantly impaired during suppression by an amount that is independent of any difference in contrast between the rivalrous stimuli. These data indicate that the magnitude of the inhibitory effect of suppression is governed by a mechanism other than that which determines suppression duration.


Levels of processing in visual illusions: the combination and interaction of distortion-producing mechanisms. In order to assess the mode and sequence of interaction of visual-geometric illusion mechanisms, responses to simple and composite overestimation configurations were measured in 72 observers. Analysis suggests that some illusion mechanisms add their distortions to the outputs of others and that other mechanisms average. A logarithmic or near-logarithmic transformation seems to occur when illusory effects combine. A path analysis of the results suggests that some illusory mechanisms combine in a serial manner and that others operate on separate parallel channels. Notions based on simple addition of illusory effects and on serial linear processing are not supported by these analyses.


A fuzzy logical model of letter identification. Stimuli were generated by factorially varying two sets of features that distinguish between two letter patterns. Subjects rated the degree to which each stimulus was an instance of one letter rather than the alternative. The obtained ratings were relatively continuous and systematic functions of the feature manipulations. The results were well accounted for by a model in which (a) each feature has an associated fuzzy predicate that is used to independently evaluate the degree to which it is true that the feature is present in the stimulus; (b) the featural truth values are integrated according to fuzzy logical expressions that correspond directly to propositional descriptions of each letter pattern; and (c) the resulting goodness of match to the stimulus for each letter is compared to that of the alternatives to determine the final identification.


Ebbinghaus illusion: context, contour, and age influence the judged size of a circle amidst circles. Subjects (groups of age 6, 8, 10, 12, and 21 years, with 60 or more persons per group) made comparative size judgments between a single circle and a standard circle that was flanked by four context circles. The context circles varied in diameter, proximity to the standard circle, and amount of circumference displayed. (When circumferences are complete, the display is the usual Ebbinghaus configuration. A variant consisted of the Ebbinghaus display with the outer three quarters of each context-circle circumference removed.) A contour-plus-context theory accounts for the data: Contours attract at every age level, and context (size of flanking circles relative to the standard circle) leads to constrast in judged size beyond age 6. Contour and context effects decreased with decreasing proximity between context circles and the standard circle.


Influence of six types of visual structure on complexity judgments in children and adults. Individuals at five grade levels (kindergarten, Grade 2, Grade 4, Grade 6, and college) made pair-comparison judgments of visual complexity. The influence of the presence or absence of six types of visual structure (double symmetry, vertical symmetry, horizontal symmetry, diagonal symmetry, checkerboard organization, and rotational organization) and of amount of contour were examined. Two general developmental trends were revealed: First, the age at which visual structure initially affected complexity judgments varied with the type of structure, independent of amount of contour, within the range of contour values used. Second, there was a uniform increase in the effect of structure on complexity judgments between the fourth and sixth grades. These results are discussed in relation to possible mechanisms of visual pattern encoding and complexity judgment.


Comparison of changes in sensitivity and sensation: implications for the response-intensity function of the human photopic system. Brightness magnitude estimations of foveally presented flashes deviate from a power function. Increment threshold functions for test lights presented upon these same flashes deviate drastically from a constant Weber fraction. These departures from the classic laws of sensation and sensitivity are shown to be in qualitative agreement and to be affected in similar ways by changes in steady adapting fields. Both sets of data can be fit over the lower range of flash intensities by models based on a saturating response function; both sets deviate from these models at high flash intensities in ways consistent with a nonsaturating response function.


Chromatic information processing.

Chromatic information processing. The investigation of visual processing mediated solely by chromatic information requires conditions preventing a subject's use of the luminance differences normally accompanying a chromatic change. In Experiment 1, which involved a discriminative reaction time (RT) task, chromatic and white stimuli of the same luminance were presented on a dimmer achromatic background. Subjects were instructed to respond only to the chromatic stimuli. RT was slowest at 570 nm and somewhat faster to short wavelengths than to long wavelengths. In Experiment 2, which compared two discriminative RT tasks, RT was faster when subjects responded to color than when they responded to white. Experiments 3 and 4 demonstrated that a brighter white surround decreased the perceived brightness of chromatic stimuli as well as their perceptual similarity to white, but did not affect RT. The results are discussed in terms of the response strength of the chromatic processing channel.


Internally augmented displays: contingent aftereffects as performance aids. Previous research on visual contingent aftereffects has been concerned with examining the effects of various parameters (e.g., spatial frequency and luminance) on the adaptation to, and decay of, contingent aftereffects. The current study tested the viability of using visual contingent aftereffects in a display context. Using established characteristics of contingent aftereffects, a program of contingent aftereffect adaptation was designed. Studies were conducted to determine if subjects who were adapted to see visual contingent aftereffects invoked by a visual display could achieve more rapid or certain identification of a display under low luminance conditions. The results confirmed (a) that contingent aftereffects can improve performance on a visual discrimination task requiring information from a display and (b) that contingent aftereffects are more enhanced at low levels of illumination.


Sensory and cognitive factors in judgments of loudness. One thousand Hertz tones were presented at equal or unequal intensities to the two ears. In a binaural-summation experiment, the presentation of components was simultaneous, the auditory system integrated the components automatically, and the subjects judged the loudness of the unitary sensation. In two cognitive-summation experiments, the presentation of components was successive, and the subjects had to integrate the two sensations consciously to judge their "total loudness." Results of all three experiments are consistent with models of linear summation of "loudness," but the loudness scales differ in the two tasks: The scales that underlie binaural summation and cognitive summation are nonlinearly related. This outcome suggests two nested processes: First, the auditory system transduces stimulus energy to loudness sensations by means of a nonlinear function; second, tasks that require subjects to judge combinational relations between sensations may impose additional nonlinear transformations on the sensations before the latter are combined.


Stimulus information and sequential dependencies in magnitude estimation and cross-modality matching. Descriptive models of magnitude estimation and cross-modality matching derived from two different approaches to psychophysical judgment, the response ratio hypothesis and the fuzzy judgment approach, are compared. The two approaches emphasize different bodies of facts but both attempt to account for sequential dependencies in psychophysical judgments. Both models suggest a hierarchical multiple linear regression model for such data. Some of the predictions of the models are explored in the context of two experiments in which the amount of stimulus information available to subjects in magnitude estimation and cross-modality matching tasks is varied. The fuzzy judgment approach generally does better in explaining the form of such data.


Time errors and differential sensation weighting. Sixteen pairs of successive tones, with different amplitude combinations, were presented with 16 combinations of tone duration and interstimulus interval. A separate group of 12 subjects was assigned to each presentation condition and made comparative loudness judgments for each of the pairs. Perceived within-pair loudness differences were scaled by a Thurstonian method using the subjective width of the "equal" category as the unit. The scale differences were well described by weighted linear combinations of the sensation magnitudes of the tones in the pairs. The time error can be regarded as an effect of this differential weighting. For the longer interstimulus intervals, the weight of the second tone was the greater, causing the usual inverse relation between time error and stimulus intensity level. For the shorter interstimulus intervals, these effects were reversed. An analysis of the pattern of weights led to the development of two models, one of which is a generalization of Michels and Helson's time error model. The weights could be interpreted as reflecting the differential efficiency of the loudness information from the two compared stimuli.


Perceptual information for the age level of faces as a higher order invariant of growth. Previous work supports the hypothesis that cardioidal strain, a nonlinear topological transformation, offers a plausible mathematical model for the perceived global changes in human craniofacial morphology due to growth. Experiment 1 examined the generality of the effect of this growth transformation on relative age judgments by applying it to profiles of a dog, bird, and monkey. Experiment 2 investigated the abstractness of this transformation by looking at its effect on perceived age level of a Volkswagen "Beetle." In both experiments, cardioidal strain resulted in changes in the perceived age of the nonhuman profiles that were similar to those produced on human faces in earlier work. A second transformation, affine shear, failed to produce as significant an effect on perceived age as cardioidal strain when applied to the same structures. Because cardioidal strain produces changes in structures that do not share an isomorphism of rigid (Euclidian) local features or rigid feature configurations, this transformation seems both sufficiently general and abstract to specify what J.J. Gibson has called a "higher-order invariant of perceptual information.


Optical motions as information for unsigned depth. Optical  motions and gradients of retinal flow have been assumed to be an important source of information for the perception of spatial layout. In the case of lateral parallax, however, the complicating effects of smooth eye movements on retinal flow fields and the known insensitivity of the visual system to absolute motion suggest that optical motions alone cannot provide the basis for accurate perception of the direction (sign) of depth relations. At most they can provide information for "unsigned" depth. Results of two experiments support the view that differential optical motions result in a strong impression of separation of objects in depth, but that the determination of near/far relations normally depends on other sources of information.


Relation between perceived depth and perceived motion in uniform flow fields. Three experiments are reported that examined the nature of the perceptual linkage between perceived depth and perceived motion in bidirectional uniform velocity fields. In such displays there is systematic misperception of both the speeds and directions of motion of visual objects. It was found that the speed and the direction of perceived motion were related to objective velocity by the addition of a uniform velocity component across the visual field. It is proposed that this uniform component may be the result of compensation for incorrectly registered ocular rotation and that such an account may also apply to classical center-surround induced motion effects.


Programmed control of aimed movements revisited the role of target visibility and symmetry. Reaction time prior to starting a 2-mm amplitude aimed movement was studied as a function to target size and experimental procedure. Consistent with a report by Klapp, choice reaction time increased as target size decreased when the visual signal that initiated the reaction time interval also indicated which of two targets was to be hit. This result implies response programming during the reaction time interval, with more programming time for slower movements to smaller targets. By contrast, in a simple reaction time procedure, there was no effect of target size on reaction time, suggesting that the response can be programmed in advance when the appropriate target is precued. This provided a control for speed-accuracy trade-off, supporting the programming interpretation of the choice reaction time result. In another condition in which both targets could be viewed while waiting for the auditory signal that initiated the reaction time interval and indicated which target to hit, choice reaction time was independent of target size provided that both possible targets on each trial were of the same size. The overall results suggest that response programs include both spatial and temporal information, and that parallel programming of different spatial goals is possible provided that the responses are of the same duration.


Moving attention through visual space.

Moving attention through visual space. Several experiments have shown that attention as measured by simple reaction time to luminance increments can be shifted in the visual field while the eyes are kept in a fixed position. The shift of attention appears to take place within 50 msec following a cue indicating the most likely position of the target. The present study reports that these shifts of attention can be time locked to a central cue. Moreover, they show that a probe event located between the cue and the target receives maximal facilitation from attention at a time prior to maximal facilitation at the target. These results provide support for an analogue movement of attention across the visual field that does not involve the suppression found during saccades.


Cognitive influences on perceptual processing. These experiments investigate the influence of frequency of occurrence of a visual stimulus (stimulus probability) on encoding processes, in an attempt to discover what sorts of mechanisms allow cognitive processes to modify perceptual processes. Experiments 1 and 2 show that frequently occurring visual letters do not facilitate encoding of visually similar letters. This implies that stimulus probability does not directly affect the feature detectors used in encoding the letters. Four more experiments provide evidence that stimulus probability has its effect on the availability of an abstract code that is generated by the encoding process from the visual input. Results from the experiments with letter stimuli could be interpreted using a model similar to the logogen model of Morton. Experiments with nonsense forms suggest that subjects use abstract codes in dealing with the forms only when the stimuli are constructed from a set of orthogonal features. A secondary finding was that visual quality has an effect that extends past the feature analysis stage and into a stage in which the visual input activities an abstract code. This result calls into question the common practice of interpreting the interaction of a factor with visual quality as evidence that the factor affects visual feature analysis.


Adaptation of speech by nonspeech: evidence for complex acoustic cue detectors. Three selective adaptation experiments were run, using nonspeech stimuli (music and noise) to adapt speech continua ([ba]-[wa] and [cha]-[sha]). The adaptors caused significant phoneme boundary shifts on the speech continua only when they matched in periodicity: Music stimuli adapted [ba]-[wa], whereas noise stimuli adapted [cha]-[sha]. However, such effects occurred even when the adaptors and test continua did not match in other simple acoustic cues (rise time or consonant duration). Spectral overlap of adaptors and test items was also found to be unnecessary for adaptation. The data support the existence of auditory processors sensitive to complex acoustic cues, as well as units that respond to more abstract properties. The latter are probably at a level previously thought to be phonetic. Asymmetrical adaptation was observed, arguing against an opponent-process arrangement of these units. A two-level acoustic model of the speech perception process is offered to account for the data.


Quantification of the hierarchy of tonal functions within a diatonic context. Listeners rated test tones falling in the octave range from middle to high C according to how well each completed a diatonic C major scale played in an adjacent octave just before the final test tone. Ratings were well explained in terms of three factors. The factors were distance in pitch height from the context tones, octave equivalence, and the following hierarchy of tonal functions: tonic tone, other tones of the major triad chord, other tones of a diatonic scale, and the nondiatonic tones. In these ratings, pitch height was more prominent for less musical listeners or with less musical (sinusoidal) tones, whereas octave equivalence and the tonal hierarchy prevailed for musical listeners, especially with harmonically richer tones. Ratings for quarter tones interpolated halfway between the halftone steps of the standard chromatic scale were approximately the averages of ratings for adjacent chromatic tones, suggesting failure to discriminate tones at this fine level of division.


Letter information and orthographic context in word perception. Theories of word perception in reading can be categorized in terms of the assumption made about whether or not a word context modifies the feature analysis of its component letters. Independence theories assume that the visual information passed on by feature analysis is independent of word context. Nonindependence theories assume that a word context directly influences visual analysis. Some nonindependence theories have assumed that word context enhances feature analysis of letters, others have assumed that word context overrides feature analysis of letters, and some have assumed that word context directs which letters are analyzed. The present experiment provided a critical test between the two classes of theories by independently varying orthographic context and visual letter information in a letter recognition task. The results contradict the qualitative predictions of the class of nonindependence theories and are accurately described by a quantification of independence theory.


Secondary task modality, expectancy, and the measurement of attentional capacity. Previous studies have obtained conflicting evidence regarding the effect of probe modality when a secondary probe task is used to measure attentional demands of a primary letter-matching task. The present experiments found no difference in the shape of the probe reaction time functions for auditory and visual probes as long as probe modality was known. When probes "unexpectedly" occurred in the modality that was different from the majority of the probes, differences were obtained. Only the unexpected auditory function changed, shape relative to the others, with reaction time to probes that occurred early in the matching task sequence being increased. The results are interpreted as supporting a role of attentional capacity in the activation of structures that accept relevant sensory input.


Implications of a transient-sustained dichotomy for the measurement of human performance. Recent evidence suggests that the human visual system has two components: a sustained system that will respond to static contrasts and a transient system that will only respond to rapid changes over time. The present article provides further support for a transient-sustained dichotomy of visual information processing by examining the effects of abrupt changes in visual stimulation in a variety of situations. Several experiments are reported in which stimuli are presented both with and without abrupt onsets. The results of these experiments, together with other evidence, suggest that the overall effects of abrupt changes in visual stimulation may be more extensive than has previously been suspected.


Modulation of the acoustic startle reflex in humans in the absence of anticipatory changes in the middle ear reflex. If a weak tone precedes an intense tone, then the acoustic startle eyeblink reflex elicited by the stronger stimulus is inhibited. It has been suggested that the leading stimulus gives rise to a protective middle ear reflex that attenuates the effective intensity of the second. This hypothesis was tested and disproved. In seven subjects intense tone bursts sufficient to elicit both intratympanic and eyeblink responses were presented sometimes alone and sometimes preceded at various lead times (25 to 400 msec) by a weak tone. The weak tone inhibited the amplitude of the eye blink to the strong tone, maximally at intervals of 100 to 200 msec, but was never seen to produce any of the anticipatory impedance changes that would be characteristic of middle ear reflex activity during the interval between the two stimuli.


Acoustic and phonological factors in vowel identification. Vowels are better identified in a consonantal syllabic context than as isolated vowels. This finding is contrary to predictions from traditional theories of vowel perception. The poor perception of isolated vowels might be attributed to a lack of dynamic acoustic cues or to familiarity effects related to the phonological rules of English. Vowel identification tests were conducted using six talkers, nine vowels, and seven syllabic contexts. Consonantal context improved vowel identification; final consonants aided identification more than initial consonants. No consistent support was found for the effect of phonological rules but duration information was seen to play a critical role. Results constitute a challenge to traditional theories of vowel perception.


Letter detection with rapid serial visual presentation: evidence against word superiority at feature extraction. Letter detection typically is faster and more accurate in words than nonwords. Experiments 1, 2, and 3 tested the robustness of the word superiority effect using rapid serial visual presentation of words or nonwords. Letter detection was better in words even when the six-letter items were presented one after the other at rapid rates, up to about 10 items per second. At yet faster rates, however, the word advantage vanished. Experiments 4 and 5 tested whether word context aids feature extraction or the subsequent interpretation stage. In Experiment 4, subjects had to discriminate whether a mutilated A or mutilated E was present; in Experiment 5, subjects had merely to decide whether a mutilated A was present. Mutilation discrimination in Experiment 4 was better on words than nonwords; once a mutilation was detected, the word context revealed whether it was an A or an E. Mutilation detection in Experiment 5 did not differ between words and nonwords, though on words there was a response bias toward not reporting a mutilation as present. The results indicate that familiarity aids the interpretation process alone: Letters are not seen any more clearly or rapidly in words, but are simply filled in or inferred more accurately from the familiar context.


Relation between cognitive and motor-oriented systems of visual position perception. Although subjects failed to detect a target displacement if it occurred near the time of a saccadic eye movement (a cognitive visual task), they were still able to point to the center of the target with an unseen pointer (a motor visual task). Pointing performance was not affected by detecting or failing to detect a stimulus displacement. The experiments demonstrate that some information that is available to a motor-oriented visual system is unavailable to the cognitive visual system, under conditions simulating normal perception.


Prototype formation from imaged, kinesthetically, and visually presented geometric figures. The issue of prototype formation from simple geometric figures presented in various modes was studied in four conditions. Base figures and their exemplars were scaled in terms of their physical similarity, which was considered to reflect cognitive similarity. Geometric exemplars were visually presented, imaged by the subject, and kinesthetically presented. Following initial presentation, a recognition task was given in which some old items, some new items, and the prototype (also a new item) were presented in the same modality as originally perceived. The results indicate that prototype formation spans a wide class of human experiences and that internal representations of geometric figures derived from experiences with one modality tend to be second-order isomorphic with similar experiences derived from another modality.


Studies of letter identification using qualitative error analysis: effects of speed stress, tachistoscopic presentation, and word context. In Experiment 1 subjects named letters under a response deadline chosen so that an appreciable number of errors would be produced. The stimulus confusions were analyzed via the same mathematical models of stimulus recognition that have been applied to the confusion matrices generated in tachistoscopic experiments. Both the Luce choice model and the informed guessing model (a new model having a simple and elegant process interpretation) provided excellent fits to the data. The parameter values of the informed guessing model changed in logical and interpretable ways with changes in the response deadline. In Experiment 2 a direct comparison was made of the types of errors produced in the data-limited tachistoscopic situation and the resource-limited response deadline situation. It was found that, relative to the response deadline task, identification in the tachistoscopic task is much more likely to be based on partial information. In Experiments 3 and 4 the same research methodology was applied to the problem of the effect of a word context on letter perception. The methodology allowed this problem to be addressed in the context of both response deadline and tachistoscopic tasks. Several advantages of the methodology for investigating other issues of interest to cognitive psychologists are discussed.


A demonstration of selection of analyzers for integral dimensions. Three experiments investigated the integrality of height and width of rectangles and the ability of observers to selectively attend to only one dimension. In Experiment 1, redundancy gain and orthogonal interference were demonstrated in a same/different task. Orthogonal interference was due to the output of the "irrelevant" analyzer interfering with the output of the "relevant" analyzer. These results indicated that height and width are integral, but they can be most parsimoniously explained by assuming that rectangles are initially processed by separate dimensional analyzers. Experiment I demonstrated that with sufficient practice (160 trials), observers are able to selectively attend to the more frequently relevant dimension. Performance for the stressed dimension increased, whereas performance for the unstressed dimension declined. Experiment 3 also demonstrated that with sufficient practice (192 trials), observers are able to selectively attend to the relevant dimension and ignore the irrelevant dimension. Orthogonal interference disappeared. The results are discussed in terms of the ability of observers to modify the perceptual process.


Holistic versus analytic process models: a reply. Two classes of stimulus process models are considered in this reply to Dykes and Cooper. It is shown that analytic models which assume that stimuli are initially processed in terms of constituent dimensions do not account for large amounts of published data. It is also shown that the holistic-discriminability model that Dykes and Cooper reject is nonetheless consistent with their results and predicts all of the data for which their analytic model was constructed to account.


Transport and metabolism of bacilysin and other peptides by suspensions of Staphylococcus aureus. L-Alanyl-L-tyrosine and glycyl-L-phenylalanine labelled with 14C competed with each other and with the dipeptide antibiotic bacilysin for transport into Staphylococcus aureus NCTC 6571 in a medium which did not support growth. They also competed with other dipeptides and several tripeptides. The fast initial transport ofthe two labelled peptides appeared to show Michaelis-Menten kinetics. Neither was transported into a bacilysin-resistant mutant of S. aureus NCTC 6571, although tyrosine was taken up by the mutant as readily as it was by the parent strain. Uptake of alanyltyrosine or glycylphenylalanine was followed by rapid hydrolysis of the peptide and the excretion of tyrosine or phenylalanine. Glycine liberated from glycylphenylalanine was partly degraded and partly incorporated into the bacterial wall. The behaviour of these dipeptides paralleled the inactivation of bacilysin by suspensions of S. aureus and the appearance of its C-terminal amino acid, anticapsin, in the extracellular fluid.


Synthesis of transfer ribonucleic acids with uridine or 2'-O-methylribothymidine at position 54 in developing Dictyostelium discoideum. In amoebae of Dictyostelium discoideum the ribothymidine (rT) content of tRNA is 0.9 mol%, but decreases progressively during development into spores. To elucidate which nucleosides replace rT at position 54 in developmental tRNA we have characterized 'vegetative' and 'developmental' tRNAs from the slime mould. Specific tRNAs were separated by two-dimensional gel electrophoresis. During early developmental stages, all tRNA species that could be separated by this method were newly synthesized. A new tRNA with uridine in place of rT and having an electrophoretic mobility similar to 'vegetative' tRNAAsn was detected during the early preaggregation stage. This 'development' tRNA was also extracted from purified polysomes. When development proceeds from preaggregation to postaggregation, tRNAs accumulate with 2'-O-methylribothymidine in place of rT. We suggest that these developmental tRNAs are important for the synthesis of specific developmental proteins.


Germination and outgrowth of Schizosaccharomyces pombe spores isolated by a simple batch centrifugation technique. Spores of the fission yeast Schizosaccharomyces pombe have been separated from vegetative cells by a simple and rapid centrifugation (800 g for 20 min) through a 35% Hypaque solution to a purity greater than 95%. Approximately 35% of the spores were recovered. Regrowth in EMM2 plus glucose showed that over 97% of the spores germinated within the first 2 h and outgrowth continued between 5 and 10 h. Sucrose induced germination in greater than 95% of the spores with a 1 h delay and outgrowth in 50% of the spores with a 3 h delay. There was little protein synthesis during germination but the protein content increased linearly coincident with outgrowth. The RNA content increased slightly during germination, but increased linearly 1 h before the onset of outgrowth and protein synthesis. After 8 h of regrowth, coincident with the onset of DNA synthesis, the rate of RNA synthesis was accelerated. The DNA content had increased 1.7-fold after 10 h of regrowth from a haploid level of 1.36 x 10(-8) microgram spore-1.


Mutations affecting pigment synthesis in Mycobacterium aurum. Pigmentation mutants of Mycobacterium aurum were isolated after chemical mutagenesis. Examination of the pigments extracted from these mutants indicated that at least 15 carotenoids were formed. beta-Carotene was not detected and the major carotene of M. aurum appeared to be leprotene. The possible biosynthetic pathway is discussed on the basis of these results.


Mass selection of conditional mating mutants of Tetrahymena thermophila. The mating reaction in Tetrahymena thermophila includes a starvation period and two distinct cell interactions, co-stimulation and cell pairing, before the cells are cytoplasmically joined as conjugants. A selection procedure for harvesting mutants unable to mate at a restrictive temperature has been developed. A conjugant pair consisting of one cycloheximide-resistant cell and one wild-type cell (cycloheximide-sensitive) was itself sensitive to the drug. By adding cycloheximide and nutrient medium to a cross made at the restrictive and grow. Repetition of the selection procedure enriched for cells unable to conjugate at the restrictive temperature. The selected cells were able to grow at 38 degrees C and could conjugate at 28 degrees C. This procedure may be narrowed to select specifically for cell interaction mutants.


Invasion of mouse brain by Mount Elgon bat virus. Mount Elgon bat virus killed mice up to 13 days of age when given intranasally. Virus reached the brain of these mice via the olfactory nerve route without obvious multiplication in any tissues other than the nasal mucosa of 1- to 6-day-old mice and in the absence of viraemia or circulating virus neutralizing antibody. Large amounts of interferon were, however, synthesized in brain where virus grew to high titres. In mice older than 13 days virus did not multiply in brain but it reached the olfactory bulbs and persisted until virus neutralizing antibody appeared in the nasopharynx. No antibody was detected in blood of the resistant mice, nor was interferon detected in their brains or nasal mucosa. Immunosuppression of the resistant mice with cyclophosphamide resulted in moderate virus growth in mid- and hind-brain accompanied by interferon synthesis and death of the mice. The local immune response prevented invasion of mid- and hind-brain in the resistant mice.


Characterization of influenza virus RNA transcripts synthesized in vitro. Polyadenylated transcripts synthesized in vitro by detergent-disrupted influenza virus resemble virus mRNAs in that they possess the complement of the 3' terminus of the genome RNAs but lack sequences corresponding to the same 5' terminal region, including the homologous sequence of nucleotides 1 to 22. Transcription is initiated at the 3' terminus by both ApG and GpG as well as in the absence of added primer.


Inhibition of protein synthesis by vaccinia virus. II. Studies on the role of virus-induced RNA synthesis. Cytoplasmic RNA synthesis can be detected in vaccinia virus-infected HeLa cells in the presence of 2 micrograms/ml but not 20 micrograms/ml of actinomycin D. When RNA synthesis is observed protein synthesis is inhibited in infected, treated cells. We had previously noted that such a correlation may also be observed in infected, cycloheximide-treated cells. If actinomycin D (20 micrograms/ml) is added to these cells at various times after infection and treatment, the inhibition of protein synthesis seen upon removal of cycloheximide does not continue beyond the point to which it had developed before the actinomycin D was added. These results indicate that the inhibition of protein synthesis can be correlated with the amount of cytoplasmic RNA synthesized in infected cells and that this RNA synthesis and the subsequent inhibition of protein synthesis can be prevented by sufficiently high concentrations of actinomycin D. The cytoplasmic RNA which is synthesized does not appear to consist of double-stranded RNA nor of extensive self complementary regions. The cytoplasmic RNA synthesized in infected, cycloheximide treated cells appears to consist of early virus mRNA which can function as mRNA in vitro in a cell-free system derived from normal cells. An examination of the phosphorylation of ribosomal proteins shows six additional phosphoproteins in infected cells, two of which may be observed in infected cycloheximide-treated cells, suggesting that phosphorylation of ribosomal proteins cannot be directly correlated with the inhibition of overall protein synthesis seen in infected cycloheximide-treated cells.


Genetic analysis of adenovirus type 2. IX. The physical locations of structural genes. Several virus-specified proteins of adenovirus type 2 (Ad2) and type 5 (Ad5) can be distinguished by their differential electrophoretic mobility in SDS-polyacrylamide gels. By comparing the physical maps of the genomes of interserotypic recombinants between ts mutants of these viruses with the pattern of proteins expressed, the physical locations of some genes can be determined on the adenovirus DNA molecule. The proteins of a total of 103 recombinants were analysed; 44 of these are of known DNA structure. Structural genes for the proteins analysed span the following loci on the conventional adenovirus map: V (30 to 43); III (43 to 44); II and 66K (55 to 57); 100K, 36K, 32K (69 to 71); IV (80 to 90).


Transcription of the genome of adenovirus type 12. V. Kinetic and size-class analyses of nuclear and messenger RNA in productive infection. In human KB cells productively infected with adenovirus type 12 (Ad12) the kinetics of synthesis of Ad12-specific RNA were investigated. Using 2 h labelling periods, striking differences were observed in the time course and the rate of synthesis of virus RNA comparing the nuclear, cytoplasmic and polysomal RNA fractions. A protracted onset of virus RNA synthesis was followed by an exponential increase between 15 and 40 h p.i.; reaching a maximum at 40 to 45 h p.i., the fraction of the newly synthesized Ad12-specific RNA remained constant up to 66 h in the nucleus, but decreased in the cytoplasm. Characteristic patterns were found in the size distribution of Ad12-specific messenger RNA synthesized early and late in the infection cycle. By using 10 min labelling periods, the size distribution and the degree of polyadenylation of the primary transcripts were determined. Early in infection, the size distribution of the virus-specific nuclear RNA resembled that of the mRNA, whereas late after infection most of the label was found in high mol. wt. RNA sedimenting between 30 and 55S. Eighty percent of the nuclear RNA was polyadenylated and belonged to the high mol. wt. RNA class. During the early phase of infection, approx. 20% of the virus genome was found to be transcribed symmetrically, and later after infection the entire Ad12 genome. Symmetrical (self-complementary) transcripts were preferentially drived from the terminal parts of Ad12 DNA.


Sindbis virus RNA replication. I. Properties of the 38s RNA species. Four species of single-stranded virus RNA (49S, 38S, 33S and 26S) were detected in chick embryo fibroblasts infected with Sindbis virus. The relative amounts of these RNAs were unaffected by the m.o.i. There was also no significant difference in the molar proportions of the four RNA species when purified virion RNA was used as the inoculum. These findings suggest that the 38S and 33S species represent products of the transcription of non-defective virion RNAs. Kinetic analyses of RNA synthesis indicated that during a 1 min pulse more radioactivity was associated with the 38S than with the 49S RNA and as the length of the pulse increased, the ratio of 38S/49S decreased, with the 49S appearing as the predominant species. Furthermore, addition of cycloheximide within the first 3 h p.i. resulted in detection of only the 49S species. Synthese of all four species was unaffected when the drug was added after this time period. These data suggest that the 38S species may represent newly synthesized 49S molecules and some protein(s) synthesized within the first 3 h p.i. is necessary for maintaining the 38S conformational form.


Amantadine-resistant and -sensitive influenza A strains and recombinants. Several influenza A strains and recombinants of fowl plague virus (FPV) with a known gene constellation were tested for amantadine sensitivity under two different experimental conditions. In a haemagglutinin yield analysis of a single growth cycle experiment FPV was found to be highly sensitive to amantadine, while in the plaque reduction and inhibition test it was highly resistant. With the A3 Hong Kong and equi 2 strains the opposite observation was made. The A2 Singapore strain was sensitive while Ao PR8 was resistant in both tests. In the haemagglutinin yield analysis of a single growth cycle all recombinants carrying segment 4 (HA) of the resistant strain were resistent against amantadine, independent of the derivation of the other genes. In the plaque reduction and inhibition test recombinants carrying the haemagglutinin of the sensitive strain were either resistant or sensitive depending on the gene constellation. Drug sensitivity was transferred by the combination of segments 5 (NP) and 6 (NA). Segment 7 (M) of certain sensitive strains seems to counteract this effect. The results are compatible with the concept that amantadine resistance or sensitivity is not confined to a single gene product or a single mechanism.


Normal lymphocyte interferon production in adult HBsAg-positive chronic active liver disease. To challenge the hypothesis that interferon (IF) production in chronic hepatitis-B virus liver disease is defective, lymphocytes from 14 patients with chronic active liver disease (CALD); from nine patients with chronic inactive liver disease (CILD), and from six healthy chronic carriers (HCC) were stimulated by Newcastle Disease virus. The patients with CILD showed a weak IF response by comparison with the controls (P less than 0.0005), whereas IF production by CALD patients and the HCC did not statistically differ from IF production in the healthy hepatitis-B surface antigen negative subjects who served as controls. These results indicate that IF treatment of CALD does not rely on a completely proved background.


SSPE-BIKEN: a naturally arising hemagglutination-defective mutant of measles virus. Biochemical and genetic methods have been used to investigate a defective variant of measles virus previously isolated from a patient with subacute sclerosing panencephalitis (SSPE). Since its isolation, this syncytiogenic strain (SSPE-BIKEN) has remained cell-associated; infected cells do not hemadsorb and do not release infectious virus. Immune precipitation and polyacrylamide gel electrophoresis were used to study the synthesis of measles virion proteins in SSPE-BIKEN-infected cells. All of the virion proteins were detected in immune precipitated whole cell extracts. However, the hemagglutinin (HA) protein was not detected on the cell surface by lactoperoxidase iodination. These results suggest that the failure of the HA protein to insert into the cell membrane accounts for the block in the release of infections virus. Radioactively labeled, noninfectious, virus-like particles have been purified from the media of SSPE-BIKEN-infected cells. These particles contain virus nucleocapsid, nucleocapsid-associated, and membrane proteins, but very little HA and hemolysin proteins. Genetic complementation between SSPE-BIKEN and a temperature-sensitive mutant of measles virus was observed and suggests that the SSPE isolate defect is due to a mutation. Additional evidence of a mutation is provided by the detection of low frequency revertant progeny in SSPE-BIKEN stocks. Our results support the hypothesis that genetic variants of measles virus are involved in the etiology of SSPE.


Modification of cognitive tempo on a haptic-visual matching task. The present experiment investigated the modification of response latencies and error rates on a haptic-visual matching test via modeling procedures (N = 60 slow and fast responding primary school boys and girls). Twenty-four slow and 24 fast responders were exposed to one of four videotaped modeling conditions depicting refelctive or impulsive strategies that were either successful or unsuccessful. Immediately following exposure to the taped model, Ss were posttested, and changes in their latencies and error rates on the haptic-vusial matching test were assessed. The remaining six slow responders and six fact responders viewed no model but participated in the same posttest procedure, thus serving as no treatment controls. The principal results indicated that the viewing of the reflective-success model significantly increased the response latencies of all Ss, particularly slow responding Ss, and that the viewing of either reflective model (success or failure) significantly decreased the error rates of fast responding Ss. The impulsive model, on the other hand, had no significant effect on either response latencies or error rates.


A developmental study of the regular-random numerosity illusion. Perceived number is influenced by item arrangement. It has been shown previously with adults that a regular pattern of dots appears more numerous than a random pattern with the same physical number. The present study used similar stimuli: two sets of 37 dots arranged within circular areas, one regular and the other random. Forty-eight grade school students were tested; they ranged in age from 5.6 to 14.8 years and included 27 girls and 21 boys. The illusion was found to increase in strength from the second to the eighth grade. The results were discussed in relation to Birnbaum and Veit's theory of contrast with expectancy.


A developmental study of three-dimensional perception in Israeli children. One hundred thirty-six 5- to 10-year-old Israeli male and female children were given three black and white photographs of a highway, a column of identical tanks, and a row of elephants, and were asked some questions on each one of the photographs in order to elicit responses of three-dimensional perception. The results showed a clear developmental pattern, quite similar to what has been found in other studies. It appears that the procedure used in the present study is an easier and probably more reliable way of assessing perspective responses than the original procedure of Piaget and Inhelder.


The "Guinea Pig" Formboard: its construction and some learning norms. A formboard test was presented to 51 male (age 20-45) and 47 female (age 18-36) Ss having a college level education. The test attempted to follow a definite principle of construction in the six figures which comprise it. Each S was presented with a set of randomly arranged blocks and asked to put them where they belonged as quickly as possible. Three successively timed trials were given. Results indicate no significant sex differences in mean time on any of the trials; a trial-to-trail improvement that is almost identical for males and females; and virtually no differences when reversals of the first order in succeeding trials over previous trials are considered. The author suggests that the task offers promise for further study of the qualitative nature of formboard response and merits standardization on a group through various age levels.


Dopa accumulation is a measure of dopamine synthesis in the median eminence and posterior pituitary. A radioenzymatic assay was employed to measure the accumulation of DOPA in a variety of rat brain tissues 30 min after the administration of a decarboxylase inhibitor in order to estimate the activity of dopamine (DA) nerves which terminate in these regions. In the median eminence and posterior pituitary the accumulation of DOPA appears to occur primarily in DA nerves since: (1) the rate of synthesis of norepinephrine (NE), as estimated from the alpha-methyltyrosine-induced decline of catecholamines, accounts for less than 10% of total catecholamine synthesis in these two brain regions; and (2) the accumulation of DOPA is not significantly altered when the NE concentrations in these regions are reduced to 40--50% of control by prior intraventricular injections of 6-hydroxydopamine. These results suggest that the accumulation of DOPA in the median eminence and the posterior pituitary can be used to estimate the activity of tubero-infundibular and tuberohypophyseal DA nerves, respectively.


Attenuation of the gamma-butyrolactone-induced increase in DOPA accumulation by chronic ethanol administration. The effect of gamma-butyrolactone (GBL) on the accumulation of dopa after inhibition of aromatic amino acid decarboxylase was studied in rats following chronic treatment with ethanol. The GBL-induced dopa accumulation was significantly decreased in ethanol-treated rats. With the increased duration of the ethanol treatment this effect appears to be more marked in the limbic forebrain. It is suggested that chronic ethanol treatment may produce a decreased sensitivity of central GABA receptors.


The role of monoamines for the central effects of Baclofen on behavior of rats. Male albino rats given a bilateral injection of Baclofen (Lioresal) (12 micrograms/rat) in the cerebral ventricles showed a behavioral syndrome of activation + ataxia, paddling, tail-pinch hyperresponse and anesthesia. The phase of activation + ataxia was reduced by pretreatment of rats with H 44/68, FLA 63, reserpine, pimozide, phenoxybenzamine, oxypertine or chlorpromazine. The phase of paddling was reduced by pretreatment with FLA 63, reserpine, phenoxybenzamine, oxypertine, chlorpromazine, pimozide + phenoxybenzamine or apomorphine, while administration of clonidine instead of Baclofen caused paddling in non-pretreated rats. The phase of tail-pinch hyperresponse was reduced by reserpine, oxypertine, chlorpromazine or pimozide + phenoxybenzamine, while none of the pretreatments affected Baclofen-induced anesthesia. Drugs which affect mainly tryptaminergic or GABA-ergic functions failed to affect Baclofen-induced behaviors consistently. The findings suggest that dopaminergic and noradrenergic functions play a role in the central effects of Baclofen on behavior of rats.


Effects of post-mortem storage on synaptic 5-HT binding and uptake in mammalian brain. Synaptosomes and synaptic membranes were isolated from rat brain after various storage times and temperatures of the tissue. Synaptosomal 5-HT uptake was diminished by about 20% within the first hour after decapitation. No significant change in the incorporation rate was observed for the seven proceeding hours if the brains were stored at room temperature. After an initial decrease of about 15%, 5-HT incorporation remained constant for at least 24 hours if the tissue was stored at 4 degrees C. Electron micrographs showed that nerve endings were highly disrupted by freezing and thawing of the brains.--The capacity of high affinity 5-HT binding to the microsomal synaptic membrane fraction decreased with the first hour by about 13% to 120--130 fmoles 5-HT/mg protein and remained almost constant for the next eight hours. Freezing at --80 degrees C of whole brain or of isolated membranes did not affect 5-HT receptor interaction.--The capacity of specific 5-HT binding to membranes isolated from human post-mortem brain was comparable to that found with synaptic membranes from rat brain. In contrast to the control values, a significant decrease in 5-HT binding was observed in membrane fractions isolated from brain after cerebral insult.


Comparison of dopamine synthesis regulation in the terminals of nigrostriatal, mesolimbic, tuberoinfundibular and tuberohypophyseal neurons. The rate of accumulation of DOPA after the administration of decarboxylase inhibitor (NSD 1015) was determined in the striatum, olfactory tubercle, median eminence and posterior pituitary of the rat brain in order to obtain an index of the rate of synthesis of dopamine (DA) in the terminals of nigrostriatal, mesolimbic, tuberoinfundibular and tuberohypophyseal neurons, respectively. In all brain regions an increase in the concentration of DA by the administration of a monoamine oxidase inhibitor decreased DOPA accumulation while a decrease in the concnetration of DA by the administration of reserpine increased DOPA accumulation. These results indicate that end product inhibition plays a role in regulating DA synthesis in all four neuronal systems. Injections of DA agonists decreased and DA antagonists increased the accumulation of DOPA instriatum, olfactory tubercle and posterior pituitary, but not in median eminence. The administration of gamma-butyrolactone (GBL) and baclofen increased the concentration of DA and the accumulation of DOPA in the striatum, olfactory tubercle and posterior pituitary, and these effects were reversed by the administration of apomorphine. On the other hand, GBL and baclofen had no effect on the concentration of DA or the accumulation of DOPA in the median eminence. These two drugs did, however, reduce the alpha-methyltyrosine-induced decline of DA in the median eminence suggesting that they inhibit the activity of tuberoinfundibular nerves just as they do DA nerves in other systems. These results suggest that the regulation of DA synthesis in terminals of nigrostriatal, mesolimbic and tuberohypophyseal nerves is different from that in tuberoinfundibular nerves in that the latter nerves appear to lack an autoreceptor regulatory mechanism.


Origin of free 3-methoxy-4-hydroxyphenylethyleneglycol. The origin of free 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG, a major metabolite of norepinephrine) in rat cerebrospinal fluid (CSF) was investigated using brain and spinal cord perfusions with artificial CSF, electrical stimulation of the locus coeruleus (LC) and the technique of retrograde cell labelling with horseradish peroxidase (HRP). The rates of appearance of MHPG into ventricular-cisternal and lumbar-cisternal perfusates were about 12.4 and 19.2 ng/hour respectively. Probenecid (200 mg/kg i.p.) did not alter the MHPG output in either preparation. Intravenous administration of 3 micrograms MHPG did not substantially enhance the outflow of the metabolite in the ventricular-cisternal perfusate, indicating that MHPG found in the perfusate is of central origin. Maximal activation of central norepinephrine (NE)-containing neurons of the LC by electrical stimulation induced a 50% increase of MHPG levels in the ventricular-cisternal perfusate. In addition HRP was found to be retrogradely transported from the lateral ventricle to these LC-neurons. These findings indicate that MHPG in CSF originates, at least in part from NE of nerve terminals adjacent to the cerebral ventricles, which have their origin in the LC. We calculated that the fraction of MHPG formed in the central nervous system, that was released into the CSF was about 34%. It is concluded that MHPG in CSF is a measure for changes in central NE turnover and that a considerable portion is dependent upon the activity of LC neurons.