Task predictability influences the variable foreperiod effect: evidence of task-specific temporal preparation.

Temporal preparation usually results in enhanced performance in choice reaction time tasks. The present study investigated to what extent temporal preparation involves increased readiness for task-specific processing requirements as opposed to increased task-independent readiness. Participants performed either a pitch, a letter, or a color discrimination task within a variable foreperiod paradigm and tasks alternated regularly between auditory and visual discriminations. In separate blocks of trials, the upcoming visual discrimination task was either predictable or unpredictable. We observed the standard variable foreperiod effect for both visual discrimination tasks irrespective of task predictability. Importantly, however, the variable foreperiod effect was larger when the visual discrimination task was predictable than when it was unpredictable. These results suggest that temporal preparation in choice reaction time tasks involves increased readiness for both task-independent and task-specific processing requirements.