Figure 1.

Set-shifting task and source grid. (A) In the set-shifting task, participants must match the target stimulus presented at the bottom of the screen to 1 of 2 choice stimuli presented at the top. Within a set of trials, the match is always made on the basis of one dimension (e.g., red if matching by color, or square if matching by shape). A set shift occurs when the matching rule changes. ID shifts are color-to-color or shape-to-shape. ED shifts are color-to-shape or shape-to-color. (B) Source locations are arranged as a uniformly distributed grid.