SCALAR TIMING IN TEMPORAL GENERALIZATION IN HUMANS WITH LONGER STIMULUS DURATIONS

Three experiments investigated temporal generalization performance in humans by using stimulus durations similar to those previously used wi th rats. In most conditions, chronometric counting was prevented by co ncurrent shadowing of temporally irregular numbers. Experiment 1 exami ned performance with visual stimuli, when the standard was 4.0 s long and nonstandard stimuli were spaced either linearly or logarithmically around the standard. Generalization gradients were asymmetrical with linear spacing but symmetrical with logarithmic spacing, a result obta ined previously with humans. Experiment 2 used auditory stimuli and va ried the standard across values of 2.0, 4.0, 6.0, and 8.0 s. All gradi ents were asymmetrical, and good superposition was obtained, indicatin g conformity to scalar timing. Experiment 3 prevented or encouraged ch ronometric counting by changing instructions, and temporal generalizat ion gradients differed when counting was and was not used.