STEP: Stimulus Information as a Determinant of Reaction Time [35168]

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Detail
Experiment Author: Adapted from STEP and used with permission of Brian MacWhinney
 
Experiment Description
This study uses information theory to explain why larger numbers of choices increase reaction time (a phenomenon described by the Hick Hyman Law). For instance, a four-choice reaction-time task will take longer than a two-choice task.

 
Experiment Instructions

This experiment uses three blocks of trials. They differ in the number of possible answers available to participants. Each trial will present a series of letters and particpants must identify the position of the letter 'A'. The first block is 20 trials and only two letters are presented. The second block is 30 trials and three letters are presented. The third block is 40 trials and there are four letters presented. Participants are to respond as quickly as possible but there is no time limit. There is a feedback screen shown after each trial that displays reaction time.
 
Experiment Citation

Hyman, R. (1953). Stimulus information as a determinant of reaction time. Journal of Experimental Psychology, 45, 188-196
 
Cited Experiment Abstract  

Though studies of the relation between reaction time (RT) and the number of stimuli or responses from which to choose dates back to at least 1885, Hick (Quarterly J. Exp. Psych., 1952, 4, 11-26) and, separately, Hyman (J. Exp. Psych., 1953, 45, 188-196) argued that RT increases linearly with the amount of information conveyed by the number of choices.  Thus, a binary (two-valued, yes/no) response has one bit of information, while a four-choice response has two bits, etc.).  In this experiment, subjects must choose between two, three, or four responses, in separate blocks of the experiment.
 
Works Cited by the Experiment

Hick, W.E. On the rate of gain of information. Quart. J. exp. Psychol., 1952, 4, 11-26.

Merkel, J. Die zeitlichen Verhaltnisse der Willensthatigkeit. Philos. St., 1885, 2, 73-127.

Shannon, C.E., & Weaver, W. The mathematical theory of communication. Urbana: Univer. of Illinois Press, 1949.