An incentive effect in thermally motivated behavior

Three shaved adult male albino rats were trained to press a lever to replace a hot air drive condition (50° C) with either a small reinforcer (32° C) or a large reinforcer (14° C). Following the 10-sec reinforcer, the drive condition was either reinstated immediately (no delay) or after a 15-sec exposure to the drive temperature, during which the bar was withdrawn (delay). Response rate during the no-delay procedure was faster for the small reinforcer than for the large. This relation reversed during the delay procedure. The former observation is similar to a satiation effect and the latter resembles an incentive effect.