The effect of d-amphetamine on short-term memory for time in pigeons.

The effect of d-amphetamine on pigeons' perception and short-term memory of time was investigated within a delayed symbolic matching to sample paradigm in which pigeons were rewarded for choosing one color after a 1-sec sample and another color after a 5-sec sample. On trials with no delay between sample offset and onset of the choice phase, d-amphetamine produced a bias toward choosing the color that was correct after long samples, suggesting that the birds overestimated the sample durations under amphetamine. With a 20-sec retention delay, d-amphetamine lowered choice accuracy to chance level, suggesting that it impaired the bird's short-term memory for sample durations. It was postulated that an amphetamine-induced increase in the rate of perceptual processing could mediate the effects of amphetamine on both time perception and memory.