ISPC effect is not observed when the word comes too late: a time course analysis

Area of Science:

• Cognitive Psychology
• Neuroscience
• Experimental Psychology

Background:

• The item-specific proportion congruency (ISPC) effect describes a reduced Stroop effect for predominantly incongruent items.
• A key debate exists whether conflict-driven control or stimulus-response contingency learning underlies the ISPC effect.

Purpose of the Study:

• To investigate the temporal dynamics of the ISPC effect using stimulus onset asynchrony (SOA).
• To differentiate the roles of contingency learning and item-specific control by manipulating SOA and set size.

Main Methods:

• Two experiments employed SOA manipulation (negative and positive SOAs) to alter contingency learning.
• Set size was manipulated to moderate the influence of contingency learning and item-specific processes.
• Awareness and reaction time (RT) distribution analyses (delta plots) were conducted.

Main Results:

• SOA manipulation significantly influenced the ISPC effect.
• A delayed word stimulus (200 ms after color) resulted in a smaller or absent ISPC effect, irrespective of set size.
• Awareness of the ISPC manipulation was higher in smaller set sizes (2-item vs. 4-item).
• Delta plots indicated a smaller ISPC effect for faster responses, increasing with response latency.

Conclusions:

• The ISPC effect is contingent on stimulus timing; it is not observed when the word stimulus is significantly delayed.
• Temporal relationships between stimulus dimensions play a crucial role in shaping the ISPC effect.
• Findings contribute to understanding the interplay between automatic learning and deliberate control in cognitive tasks.