Spaced-trials reward magnitude effects in the rat: Single versus multiple food pellets.

Abstract

Sixty rats were trained in a runway with either small-or large-reward magnitude. Both small and large rewards were presented in single-or multiplepellet form. One training trial was given each day for 120 days. Early in training the large-reward animals ran faster than those receiving small reward and the effect was more pronounced in the multiple-pellet condition. Later in training the small-reward animals equaled the performance of the animals receiving large reward and even ran somewhat faster in the run section of the alley. The typical extinction effect of greater persistence for smallreward animals was observed, but only in the goal section.Both Black (1969) and McCain, Dyleski, and McElvain (1971) have published several experiments seriously questioning the long-held assumption that instrumental performance increases in strength with increases in reward magnitude. McCain et al. compared large (one 500-mg. pellet) and small (one 45-mg. pellet) reward in a runway after 24, 54, 60, 70, 78, 90, 116, or 135 training trials. They reported that large reward facilitated running speeds after limited training (24 trials) but that the effect was minimal or nonexistent after extended training (54-135 trials). The typical extinction finding of greater persistence after training with small reward than after large reward was observable somewhat longer. McCain et al. reported extinction differences to be reliable after 24-90 trials but not after 116 or 135 trials.Most of the experiments reviewed by

Extended training and multiple shifts: Percentage of reward

“…There now exists a very substantial body of evidence indicating that under these conditions any initial acquisition differences due to reward magnitude disappear after extended training (e.g., Black, 1969;Campbell, Batsche, & Batsche, 1972;McCain, 1970;McCain et aI., 1971;McCain et aI., 1976;Shanab, France, & Young, 1976). Similar effects were seen when different magnitudes of 50% reward were given (Capaldi & Freese, 1974;McCain, 1970;Meyers & Anderson, 1975).…”

Hey Garvin! Science is a game: A reply to McCain, Ward, and Lobb

“…It was pointed out that studies by Black (1969) and Campbell, Batsche, and Batsche (1972) have been reported in which satiation effects were taken into account and reward magnitude effects failed to develop. We again would agree with McCain, Ward, and Lobb that it is nice "to have a colleague in another laboratory examine the possible effects of satiation."…”

The effects of preexperimental diet upon reward magnitude effects

“…At best, the once widely held assumption that large magnitudes result in superior performance appears to be on somewhat shaky ground. Data reported by Black (1969), Campbell, Batsche, and Batsche (1972), McCain (1970), andMcCain, Dyleski, andMcElvain (1971) have suggested, rather convincingly, that under some conditions reward magnitude effects may be rather transitory, if they develop at all.…”