Task and information conflicts in the numerical Stroop task.

Studies of the Stroop color-word task have provided evidence for the existence of two conflicts: (1) an early task conflict between noting the relevant color and reading afforded by the irrelevant word (or word-like stimuli), and (2) a late information conflict between the information provided by the word and the information provided by the color. Measurements of pupil changes, in addition to reaction time (RT), have extended understanding regarding these two conflicts. The current work examines the generalizability of such understanding. We ask whether similar processes work in the comparative judgment of numbers (e.g., in the numerical Stroop task). We present two experiments that support and extend the knowledge gained in the word-color context to numerical processing. Similar to results with the Stroop color-word task, we found a dissociation between RT and pupillometry and an early task conflict followed by an information conflict.