Sensory Memory  Short-Term Memory (STM)  Long-Term Memory (LTM)  3-36  Sensory memory is the part of the memory system that receives initial stimuli from the environment and processes them according to  the individual’s preconceived concept of what is important. Other factors can influence the reception of information by sensory  memory. For example, if the input is dramatic and impacts more than one of the five senses, that information is more likely to make  an impression. The sensory memory processes stimuli from the environment within seconds, discards what is considered extraneous,  and processes what is determined by the individual to be relevant. This is a selective process where the sensory register is set to  recognize certain stimuli and immediately transmit them to the STM for action. The process is called precoding. An example of  sensory precoding is recognition of a fire alarm. No matter what is happening at the time, when the sensory register detects a fire  alarm, the working memory is immediately made aware of the alarm and preset responses begin to take place. Sensory memory is  capable of retaining information for only a very short period of time and within seconds the relevant information is passed to the  STM.  Short-term memory is the part of the memory system where information is stored for roughly 30 seconds, after which it may rapidly  fade or be consolidated into long-term memory, depending on the individual’s priorities. Several common steps help retention in$_{ }$ STM. These include rehearsal or repetition of the information and sorting or categorization into systematic chunks. The sorting  process is usually called coding or chunking. A key limitation of STM is that it takes 5–10 seconds to properly code information and  if the coding process is interrupted, that information is easily lost since it is stored for only 30 seconds. The goal of the STM is to put  the information to immediate use.  STM is not only time-limited, it also has limited capacity, usually about seven bits or chunks of information. A seven-digit  telephone number is an example. As indicated, the time limitation may be overcome by rehearsal. This means learning the  information by a rote memorization process. Of course, rote memorization is subject to imperfections in both the duration of recall  and in its accuracy. The coding process is more useful in a learning situation. In addition, the coding process may involve recoding to  adjust the information to individual experiences. This is when actual learning begins to take place. Therefore, recoding may be  described as a process of relating incoming information to concepts or knowledge already in memory.  Brain research has led to the conclusion that STM resembles the control tower of a major airport and is responsible for scheduling  and coordinating all incoming and outgoing flights. STM has three basic operations: iconic memory, acoustic memory, and working  memory. Iconic memory is the brief sensory memory of visual images. Acoustic memory is the encoded memory of a brief sound  memory or the ability to hold sounds in STM. Of the two, acoustic memory can be held longer than iconic memory. Working memory  is an active process to keep information until it is put to use (think of a phone number repeated until used). It is useful in remembering  a spoken sentence or a string of digits.  Also called “scratch-pad” memory, working memory is of short duration and has limited capacity. It simultaneously stores and$_{ }$ manipulates information. The goal of the working memory is not really to move the information from STM to LTM, but merely put  the information to immediate use.  STM retention makes information available long enough for it to be rehearsed. For example, if the learner repeats the number to  himself, it can be transferred to some sort of longer term storage. To retain information for extended periods of time, it needs to be  transferred from STM to LTM. This process involves encoding or consolidation of information into LTM where it can then be  retrieved.  LTM is relatively permanent storage of unlimited information, and it is possible for memories in LTM to remain there for a lifetime.  What is stored in LTM affects a person’s perceptions of the world and affects what information in the environment is noticed.$_{ }$ Information that passes from STM to LTM typically has some significance attached to it. For example, imagine how difficult it would  be for a pilot to forget the first day he or she soloed. This is a significant day in any pilot’s training, so when the information was  processed, significance was attached to it, the information was deemed important, and it was transferred into LTM.  There appear to be other reasons information is transferred to LTM because the average human brain stores numerous insignificant  facts. One explanation is repetition; people tend to remember things the more they are rehearsed. Information also ends up in LTM  because it is somehow attached to something significant. A person may remember the color of the clothing of the recipient of a  wedding proposal. The color of the clothing plays no important role, but is attached to the memory of the experience. 