Abstract: | Previous results have shown that there is an increased difference between intradimensional (ID) and extradimensional (ED) shifts when subjects shift to a nonpreferred dimension. Fisher and Zeaman (1973) have indicated that such findings can be explained not only by their attention-retention theory, which assumes that attention is completely modifiable, but also by models which assume that attention has a fixed, nonmodifiable component. The present experiment showed that the larger ID-ED difference with a nonsalient dimension is solely attributable to the improved performance of the ID shift condition, a results which is more consistent with the assumption of complete modifiability of attention. |