Allocation of attention and production of time intervals

14 students enrolled in introductory psychology classes engaged in several trials of card sorting to acquire the rule for correct sorting. They also were instructed to keep track of time simultaneously and to continue sorting for what they believed was 20 sec. The duration of card sorting was significantly greater for the first sorting trial, during which the rule was unknown, relative to the second consecutive trial of errorless sorting when the rule had been learned. After a shift in the rule mean sorting duration was reduced from the second errorless trial but returned to a value comparable to that on the first sorting trial. Results are interpreted in terms of the attention-allocation model of time estimation.