Delta plots for conflict tasks: An activation-suppression race model.

Area of Science:

• Cognitive Psychology
• Computational Neuroscience
• Psychophysics

Background:

• The Simon task is a widely used experimental paradigm to study cognitive control.
• Negative-going delta plots in reaction times (RTs) are a common observation in Simon tasks, but their underlying mechanisms remain debated.
• Existing models often struggle to fully capture the nuances of these RT distributions.

Purpose of the Study:

• To introduce a mathematically simple yet precise model of activation suppression.
• To explain the negative-going delta plots observed in standard Simon tasks.
• To provide a computational framework for analyzing Simon task data.

Main Methods:

• A race model is proposed, pitting stimulus attribute identification against the suppression of irrelevant location-based activation.
• The model incorporates a critical time window where irrelevant activation influences processing if not fully suppressed.
• Maximum likelihood estimation is used to fit the model to observed RT distributions from congruent and incongruent trials.

Main Results:

• The proposed activation suppression model successfully explains the negative-going delta plots.
• The model provides good fits to two previously reported empirical data sets.
• Plausible parameter values were obtained, supporting the model's validity.

Conclusions:

• The model offers a parsimonious explanation for key findings in the Simon task.
• It advances our understanding of the interplay between stimulus processing and inhibitory control.
• The provided R and MATLAB software facilitates further research and application of the model.