A computational model of the Simon effect

Marco Zorzi, Carlo Umiltá

Research output: Contribution to journalArticlepeer-review


Even though stimulus location is task irrelevant, reaction times are faster when the location of the stimulus corresponds with the location of the response than when it does not. This phenomenon is called the Simon effect. Most accounts of the Simon effect are based on the assumption that it arises from a conflict between the spatial code of the stimulus and that of the response. In this paper a computational model of this hypothesis is presented. It provides a computationally explicit mechanism of the Simon effect. Consistent with human performance, the model provides reaction times that indicate both an advantage for the ipsilateral, corresponding response (i.e., facilitation) and a disadvantage of the contralateral, noncorresponding response (i.e., inhibition). In addition, the model accounts for the fact that the size for the effect depends on task difficulty.

Original languageEnglish
Pages (from-to)193-205
Number of pages13
JournalPsychological Research
Issue number3
Publication statusPublished - Dec 1995

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Psychology(all)


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