|
The effects of d-amphetamine
and haloperidol on temporal discrimination. The ability to estimate the duration of events can be assessed using human and animal discrimination paradigms in which subjects report whether they have just experienced a relatively short stimulus event (e.g., 3 seconds of light illumination) versus a relatively long stimulus event (e.g., 9 seconds of light illumination). Using Log d and Log bias to measure temporal discrimination performance the present research examined the suggestion that alterations in dopamine activity should alter the ability of subjects to make accurate temporal judgements. This alteration in ability to make temporal judgements may result from either a speeding up (in the case of dopamine agonists) or slowing down (in the case of dopamine antagonists) of an internal clock mechanism. Consistent with this view d-amphetamine produced systematic biases in rats towards reporting that a long duration stimulus had occurred at the start of a trial, irrespective of whether a short or long stimulus had actually been presented. Haloperidol, however, tended to reduce temporal discrimination accuracy without producing any systematic response biases, either towards reporting 'short' or 'long'. The present findings pose a problem for interpretations of these drugs solely in terms of either the speeding up or slowing down of an internal clock mechanism. Keywords: temporal discrimination, timing, bias, d-amphetamine, haloperidol |
|
|
|
|
|
|
|
|
|