Fig. 1.

The shape and line exemplars used for the various stages of the attentional set-shifting paradigm. In this example the dimension of “shape” is relevant in all the discriminations except that requiring an EDS (d) and reversal (e) and subsequent IDS II (f). On any one trial of a compound discrimination, a shape exemplar may be paired with one or other of the line exemplars. Correct and incorrect choices are indicated by + and −, respectively. Gray typefacespecifies that “shape” is the relevant dimension, whereasblack typeface specifies that “line” is the relevant dimension.