Evaluation of rate-dependency and internal clock effects of d-amphetamine

► The effect of d-amphetamine on timing behavior was evaluated using the peak procedure. ► d-Amphetamine increased the variability of the response distribution. ► In contrast, it did not change the location of the peak time. ► No differences were found as due to the length of training, minimum or extended. ► These results are compatible with the rate-dependency hypothesis.