Divided attention: Storing and classifying briefly presented objects.

Although in many studies divided attention has been examined by having people perform the same task (e.g., report or search) with a large number of objects, in few studies have people had to perform two logically independent tasks involving the same brief display. In two experiments, subjects saw 200-msec arrays of characters. In dual-task blocks, theyclassified the color of some or all of the items (making an immediate response) andstored the shape of some of the items for a later recognition test. There was not much mutual interference between classifying and storing per se. However, the tasks were by no means independent: there was substantial interference whendifferent objects from the array had to be stored for one task and classified for the other. The results confirm that wholly unrelated visual tasks depend on the same input-attention system and suggest that attending to an object for any purpose may entail storing a representation of it in visual short-term memory.