Stimulus presentation rate dissociates sequential effects in event-related potentials and reaction times

Area of Science:

• Cognitive Neuroscience
• Psychophysiology

Background:

• Sequential effects, where a stimulus influences responses to subsequent stimuli, are well-documented in reaction times (RTs).
• The impact of stimulus presentation rate on these sequential effects in brain activity, specifically event-related potentials (ERPs), remains less understood.

Purpose of the Study:

• To investigate how varying stimulus presentation rates influence sequential effects in both RTs and ERPs.
• To examine the relationship between sequential effects in RTs and ERPs, particularly the P300 component and early electrophysiological measures.

Main Methods:

• Participants performed a tone-discrimination task with equiprobable stimuli.
• Stimuli were presented at fast (1.3 s) and slower (2.1 s, 2.9 s) interstimulus intervals (ISIs).
• Reaction times (RTs) and event-related potentials (ERPs), including P300 and lateralized readiness potential (LRP), were recorded.

Main Results:

• Sequential effects in RTs remained consistent across all ISIs.
• The P300 amplitude repetition effect, a common sequential effect, was present only at the fastest ISI (1.3 s).
• Sequential effects were detected early in the lateralized readiness potential (around 100 ms) and in P300 latency, irrespective of ISI.

Conclusions:

• The dissociation between RT and P300 sequential effects suggests they are not driven by a single expectancy mechanism.
• Early sequential effects in LRP and P300 latency support a continuous information processing model.
• Stimulus presentation rate critically modulates the manifestation of sequential effects in neural activity.