Memory and Simple Reaction Time

J. Greg Anson, Brian I. Hyland, Amir A. Mohagheghi,
Louise Parr-Brownlie, Sonja Bowe,
Kimberlee Jordan, & Jeffery R. Wickens

University of Otago, Dunedin, New Zealand


Reaction time is the measured time between an imperative stimulus and the onset of movement. The measure is called simple reaction time when both event and temporal uncertainty are minimal. For example, the time to initiate extension of the index finger to release a switch in response to a loud tone presented after a 1.0-1.5 s foreperiod is described as simple reaction time (SRT). In a SRT task the participant knows precisely what response to initiate before the stimulus occurs and presumably can take advantage of this information to prepare the response. Similarly, when one of say, four responses is precued, the participant knows precisely what response to execute when the stimulus occurs.

Recently we have investigated the effect of continuous versus discontinuous (300 ms) precue presentations on SRT to upper limb responses (pronation or supination; elbow extension or flexion). Although just a single target is precued, the participant in the discontinuous precued condition must remember which target was signaled, for 450 to 1150 ms until the stimulus occurs. This is known as the "memorized" condition. The continuous precue presentation is the "nonmemorized" condition. Results from five experiments will be presented. In three experiments memorization resulted in significantly (p<.05) longer reaction times. In one experiment the same trend was observed but was not significant (p>.05). And, in one experiment there was no trend (p>.05). It is perhaps surprising that a difference in SRT between memorized and nonmemorized occurs at all given that event uncertainty and temporal uncertainty are the same in both conditions. The notion that memorization requires the brain to do more "work" and that this may increase the information processing load, resulting in an increase in SRT is one possible interpretation.