Intraindividual reaction time variability affects P300 amplitude rather than latency.

Area of Science:

• Cognitive Neuroscience
• Neurophysiology

Background:

• Intraindividual response variability is a key aspect of cognitive function.
• Understanding the neural basis of reaction time variability is crucial for cognitive research.

Purpose of the Study:

• To investigate the neural correlates of intraindividual response variability.
• To examine the relationship between P300 event-related potentials and reaction time (RT) in a choice reaction time (CRT) task.

Main Methods:

• Analyzed reaction times (RTs) from faster and slower portions of the RT distribution.
• Computed P300 event-related potentials (ERPs) associated with aggregated RTs.
• Assessed independent behavioral measures of executive function and IQ.

Main Results:

• P300 amplitudes were significantly greater for faster relative to slower behavioral responses across multiple scalp regions.
• P300 peak amplitude latencies did not differ based on behavioral RT speed.
• Controlling for executive function measures reduced shared variance in P300 amplitude between faster and slower trials.

Conclusions:

• P300 amplitude, not latency, is associated with behavioral reaction time speed.
• Fluctuations in executive control may underlie variability in speeded responding.