THE RELATIONSHIP BETWEEN THE NUMBER OF PRESENTED STIMULI AND PROSPECTIVE DURATION ESTIMATES - THE EFFECT OF CONCURRENT TASK ACTIVITY

The attention/distraction models of prospective time estimation predic t either a negative relationship or an independence between duration e stimates and the number of stimulus events presented during the time p eriod, but not, a positive relationship. Two experiments examined this relationship under prospective conditions. Lists of words were presen ted during a 60-sec time period at either a fast or a slow rate. Subje cts either passively viewed the words or actively responded by perform ing either a graphemic of a semantic classification task on each word. To measure subjective duration, the method of magnitude estimation wa s used in Experiment 1 and the method of reproduction was used in Expe riment 2. Time estimates were independent of the number of presented w ords in the passive viewing condition, and negatively related in the c lassification task conditions. Furthermore, the two classification tas ks had similar effects on time estimates. These findings are consisten t with the attentional models of prospective timing, and they question the robustness of earlier findings of a positive relationship between time estimates of moderately long intervals and the number of present ed stimuli under conditions of minimal processing of the interval even ts.