ATTENTIONAL RESOURCES IN TIMING - INTERFERENCE EFFECTS IN CONCURRENT TEMPORAL AND NONTEMPORAL WORKING-MEMORY TASKS

Three experiments examined interference effects in concurrent temporal and nontemporal tasks. The timing task in each experiment required su bjects to generate a series of 2- or B-sec temporal productions. The n ontemporal tasks were pursuit rotor tracking (Experiment 1), visual se arch (Experiment 2), and mental arithmetic (Experiment 3). Each non te mporal task had two levels of difficulty. All tasks were performed und er both single-and dual-task conditions. A simple attentional allocati on model predicts bidirectional interference between concurrent tasks. The main results showed the classic interference effect in timing. Th at is, the concurrent nontemporal tasks caused temporal productions to become longer (longer productions represent a shortening of perceived time) and/or more variable than did timing-only conditions. In genera l, the difficult version of each nontemporal task disrupted timing mor e than the easier version. The timing data also exhibited a serial len gthening effect, in which temporal productions became longer across tr ials. Nontemporal task performance showed a mixed pattern. Tracking an d visual search were essentially unaffected by the addition of a timin g task, whereas mental arithmetic was disrupted by concurrent timing. These results call for a modification of the attentional allocation mo del to incorporate the idea ol specialized processing resources. Two m ajor theoretical frameworks-multiple resource theory and the working m emory model-are critically evaluated with respect to the resource dema nds of timing and temporal/nontemporal dual-task performance.