Uncertainty, timekeeping, and simple reaction time.

Area of Science:

• Cognitive Psychology
• Human Factors
• Psychophysics

Background:

• Event and time uncertainty can influence simple reaction time (RT).
• Previous hypotheses suggested memory effects or faulty reinstatement of foreperiods might explain these RT variations.
• The role of participant "unwillingness" to prepare for uncertain events requires further investigation.

Purpose of the Study:

• To test the hypothesis that response time (RT) effects from event and time uncertainty are caused by participant "unwillingness" to prepare for unlikely events.
• To differentiate this "unwillingness" hypothesis from alternative explanations involving memory effects.
• To examine the consequences of inaccurate timekeeping on RT.

Main Methods:

• Two experiments were conducted comparing the traditional foreperiod method with a novel transit-signal method.
• The transit-signal method was designed to minimize memory effects associated with foreperiods.
• Reaction time (RT) was measured under varying degrees of event and time uncertainty.

Main Results:

• The inverse relationship between RT and event uncertainty was confirmed using the transit-signal method, independent of memory effects.
• Time uncertainty resulted in a steeper initial RT gradient with the transit-signal method, where precise temporal information was available.
• The observed uncertainty effect persisted even when participants could theoretically overcome it, supporting the concept of "unwillingness".

Conclusions:

• Participant "unwillingness" to prepare for uncertain events is a significant factor influencing reaction time (RT).
• This "unwillingness" is related to the perceived utility associated with preparation.
• The assumption that inaccurate timekeeping invariably increases RT was not supported by the findings.