Simon Effect: what it is and how it is studied in psychology


Sometimes people have such automated responses in their brains that conflicts arise when it comes to solving certain tasks that “contradict” such automation. In this article we will know one of these interferences, the Simon effect .

The Simon effect was proposed by J.R. Simon at the end of the 1960s, and consists of responding more quickly and correctly when the stimulus that we must detect appears in the same relative space as the response to be emitted.

The Simon effect: what is it?

In a study of basic psychology , which consisted of an auditory task where the subjects had to identify the frequency at which a certain sound was emitted, by pressing the button on the right for low frequencies, and the left for high frequencies. The sounds were presented randomly in one or the other ear.

Despite the fact that initially, when the paradigm was proposed, the initial hypothesis was that the origin of the sound was irrelevant to the task, the results of the study contradicted this hypothesis, since the subjects tended to respond in a stereotypical way in the same sense as the origin of the stimulus: this phenomenon, discovered by Simon and Berbaum (1990), is known as the Simon effect.

The Simon effect is considered an interference phenomenon , which is located in the response selection stage by the subject (when he must respond). This means that this effect affects the response stage in the processing of information.

Thus, the Simon effect refers to the fact that the reaction times of a subject when responding are usually faster, and the reactions or responses more accurate (more precise), when the stimulus to be detected appears in the same relative location as the response (as we have seen above). This happens even if the location of the stimulus is irrelevant to the task at hand.

The name of the effect is due to the fact that it was J.R. Simon who first published the phenomenon, at the end of the 1960s. J.R. Simon’s original explanation was that there is an “innate tendency to respond to the source of the stimulus”, the source being understood as the place of origin or source of the stimulus.

In other words, the Simon effect appears in a given task when an interference occurs ; in this case, the position of the stimulus and the assigned response do not correspond. The effect would be the result of a conflict between the irrelevant information from its spatial position (e.g., it appears on the right) and the relevant information transmitted by the stimulus.

Information processing models

The simple models of information processing, establish three stages for information processing:

  • Identification of the stimulus.
  • Response selection.
  • Execution of response or motor stage.

In this sense, as we have already seen, it is thought that the simon effect would imply an interference in the second stage, the response selection stage .

Explanation by J.R. Simon

J.R. Simon (1969) argues that the position of the stimulus (although irrelevant to the task), directly influences the selection of the response. This is because there is an automatic tendency to react towards the source of the stimulus, so that the performance is worse if the stimulus there demands an opposite response.

The explanations for understanding the Simon effect mostly refer to the interference mentioned in the response selection stage when making a decision; neurologically, it is believed that the anterior cingulate cortex would be involved in such processing , and it is thought that it could be responsible for originating the Simon effect.

Thus, it can be argued that information about the position or source of the stimulus could not be ignored, and would significantly affect our decision or response, even if the respondent knows that the information is irrelevant.

Other explanations

Another explanation for the Simon effect is that it is due to the automatic generation of conflicting spatial codes. Thus, the fact that the Simon effect is greatest when responses are given relatively quickly, suggests that may depend on an automatically generated spatial code , which remains active for a short period.

On the other hand, and at the same time, the inverse Simon effect shows that it is possible that the effect appears with responses emitted in a slower way, which demonstrates the possible participation of intentional processes of logical recoding under the control of the subject.

The Stroop Effect

The Simon effect produces u in interference similar to that produced by the Stroop effect . The Stroop effect (or Jaensch effect) consists of a semantic interference produced as a consequence of our automaticity when we read; this happens when the meaning of the word interferes with the task of naming, for example, the color with which it is written.

So, if for example we see the word “red” written in black, and we must say the color and not the word, we will take longer to respond and we will make a mistake more easily than if the word is “black”, it is written in black, and we must also say the color (because it matches).

Bibliographic references:

  • Alvarado, J.M. and Santisteban, C. (2004). Response compatibility and the effect Simon Jesús Mª Alvarado and Carmen Santisteban. Psicothema, 16,(2), 276-281.
  • Simon, J. R. (1969). Reactions to the source of stimulus. Journal of experimental psychology, 81, 174-176.
  • Simon, J.R., Acosta, E. Jr., Mewaldt, S.P. and Speidel, C.R. (1976). The effect of an irrelevant directional cue on choice reaction time: Duration of the phenomenon and its relation to stages of processing. Perception and Psychophysics, 19, 16-22.
  • Simon, J.R. and Berbaum, K. (1990). Effect of conflicting cues on information processing: the “Stroop effect” vs. the “Simon effect”. Acta Psychologica, 73, 159-170

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