Practice-induced and sequential modulations in the Simon task: evidence from pupil dilation

Recent evidence showed that pupil dilation (PD) reflects modulations in the magnitude of the Simon interference effect due to correspondence sequence. In the present study we used this measure to assess whether these modulations, thought to result from cognitive control mechanisms, are influenced by prior practice with an incompatible stimulus-response (S-R) mapping. To this end, PD and reaction times (RTs) were recorded while participants performed a Simon task before and after executing a spatially incompatible practice. The sequential analysis revealed that PD mirrored the conflict-adaptation pattern observed in RTs. Crucially, sequential modulations were not affected by prior practice. These findings support the view that the modulations of the Simon effect due to prior practice and those due to correspondence sequence result from two different mechanisms, and suggest that PD can help to better understand the mechanisms underlying response selection and cognitive control in the Simon task.