Contingency learning on the proportional congruency effect of the Stroop task is manifest in deviant processing

Area of Science:

• Cognitive Psychology
• Neuroscience
• Experimental Psychology

Background:

• The proportion congruency effect, observed in interference tasks, describes how the proportion of congruent versus incongruent stimuli influences performance.
• Previous research suggests this effect may relate to attentional mechanisms, but the underlying cognitive processes require further elucidation.

Purpose of the Study:

• To investigate the cognitive mechanisms responsible for the proportion congruency effect in a two-choice Stroop task.
• To utilize event-related potential (ERP) components associated with deviant processing to understand how stimulus congruency and proportion influence cognitive control.

Main Methods:

• Participants performed a two-choice Stroop task using Kanji characters ('red', 'blue') presented in congruent or incongruent colors.
• Stimuli were presented in rare (20%) and frequent (80%) conditions for both congruent and incongruent types.
• Event-related potentials (ERPs), specifically N1 and posterior negativity, were recorded to analyze neural responses.

Main Results:

• Enhanced N1 component was observed in the rare condition compared to the frequent condition for both stimulus types, suggesting feature integration difficulties.
• Posterior negativity differed between rare and frequent conditions, indicating visual mismatch negativity for both congruent and incongruent stimuli.
• The distinction between stimulus types was less pronounced in mostly incongruent blocks, implying reduced engagement of selective attention.

Conclusions:

• The proportion congruency effect in this task is better explained by contingency learning rather than solely by selective attention.
• Deviant event-related potential components provide insights into the cognitive mechanisms underlying the proportion congruency effect.