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

• Combined chronometric approach with RT distributional analyses in the Simon task. • Observed interactive mean RT patterns of congruency and stage-specific manipulations. • Observed decreasing RT and PE delta plots for congruency effects in all conditions. • Delta plot analyses reveal influences on congruency effects not evident in mean RT. • Effects of some manipulations on delta plots not explained by fading activation. We combined analyses of reaction time (RT) distributions with experimental manipulations of different processing stages (perception, decision, motor execution) in a Simon task to investigate which changes in Simon effects could be explained entirely by fading irrelevant response activation. Consistent with fading activation accounts, the Simon effect on mean RT was usually smaller for conditions with slower responses (Expts. 1–3 but not Expt. 4), and delta plot analyses revealed that it was always smaller for the slower responses within each condition. Critically, however, these analyses also revealed that some experimental manipulations produced upward or downward shifts in the RT delta plots, thus altering the Simon effect on mean RT in ways that could not be explained by fading activation. The results demonstrate the power of combining RT distributional analyses with experimental manipulations to reveal mechanisms contributing to the Simon effect that would not be revealed using only mean RT. We consider alternatives to fading activation accounts of decreasing delta plots and discuss the contribution of different cognitive stages in modulating Simon effects. [ABSTRACT FROM AUTHOR]