Beyond mean reaction times: Combining distributional analyses with processing stage manipulations in the Simon task

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Factors

Background:

• The Simon task is a widely used paradigm to study response inhibition and cognitive control.
• Fading activation accounts propose that irrelevant response activation decays over time, influencing performance.
• Previous research often relies on mean reaction time (RT) to infer cognitive processes.

Purpose of the Study:

• To investigate the extent to which Simon effects can be explained by fading irrelevant response activation.
• To explore the contribution of different processing stages (perception, decision, motor execution) to the Simon effect.
• To determine if reaction time distributional analyses reveal mechanisms not apparent from mean RT alone.

Main Methods:

• Combined reaction time (RT) distributional analyses with experimental manipulations targeting perception, decision, and motor execution stages.
• Utilized the Simon task, a standard cognitive paradigm.
• Employed delta plot analyses to examine RT distributions and Simon effects across different conditions.

Main Results:

• Simon effects on mean RT generally decreased with slower responses, consistent with fading activation (Expts. 1-3).
• Delta plot analyses consistently showed smaller Simon effects for slower responses within conditions.
• Experimental manipulations induced shifts in RT delta plots, indicating Simon effects not solely explained by fading activation.

Conclusions:

• Fading activation is a contributing factor to Simon effects, but not the sole explanation.
• RT distributional analyses combined with experimental manipulations offer a more comprehensive understanding of cognitive mechanisms.
• Different cognitive stages play crucial roles in modulating Simon effects, necessitating nuanced analytical approaches.