Response latency as a function of amount of reinforcement.

Food-deprived rats were trained to press and hold down a telegraph key in the presence of a light. Subsequent release of the key during a tone was followed by 0.15 ml of a 20-percent sucrose solution as reinforcement. The Ss were subsequently shifted to a 0-percent and to a 5-percent solution from the 20-percent base line. The median RT and the variability of RT increased markedly as a result of the shift to the lower sucrose concentrations. For all Ss, the change in median and variability was greater for the shift to the 0-percent solution than for the shift to the 5-percent solution. It is probable that median RT and variability of RT are inversely related to amount of reinforcement.