Three groups of rats were allowed to make either 0, 40 or 285 rewarded bar-pressing responses and then were given a choice between eating pellets from a dish (freeloading) or pressing the bar. 3 independent groups ( Ss randomly assigned) were allowed to make either 0, 40, or 285 rewarded runs in a 4-ft. runway and then were given a choice between freeloading in the start box or running the maze. For all 6 groups a “total time” score was obtained which reflected the average time taken to stop freeloading and perform either one bar-pressing response or one run to the goal box. The 3 runway groups showed a marked tendency toward higher total time scores with increasing amounts of training whereas the three Skinner-box groups showed a trend in the opposite direction.
An investigation was conducted to examine the relative influence of N-R. R-N. and R-R transitions on the extinction performance of albino rats following abbreviated training in a runway. The results were discussed in relation to the modified aftereffects hypothesis.Within a partial reinforcement pattern, the four basic kinds of trial sequences (transitions) which may occur are N-R, N-N, R-R, and R-N. Recent research attests to the importance of considering these different types of transitions as the basic logical units to be employed in an analysis of the effects of partial reinforcement on the performance of albino rats in instrumental reward learning situations.Spivey (1967) found that following abbreviated training in a runway extinction performance was an increasing function of number of N-R transitions and was independent of reinforcement percentage. Spivey, Prada, & Black (1967) have reported that with extended training R-N transitions act to reduce the resistance to extinction of an operant response. Finally, Spivey, Hess, & Aponte (1967) found that resistance to extinction for rats given abbreviated training in a runway was an increasing function of R-R transitions. The results of each of these three studies were interpreted as supporting the modified aftereffects hypothesis (Capaldi, 1967).The present investigation was concerned with comparing, within a single experiment, the relative effects of N-R, R-N, and R-R transitions on extinction performance following abbreviated training.
MethodThe Ss were 36 naive, 90-day-old, male albino rats of the Sprague-Dawley strain, supplied by the Holtzman Co. of Madison, Wisconsin. Twelve Ss were randomly assigned to each of three groups.The apparatus was a wire-covered plywood runway. 75 in. long x 4 in. wide x 9 in. deep. The initial 60 in. midgray portion was separated from the 15 in. flatblack goalbox (GB) by an aluminum guillotine-type door which was used to prevent retracing. At the rear of the GB was a two-compartment aluminum food cup which could be moved perpendicular to the alley so that only one compartment, measuring 2x4x1-1/2 in., was in the GB at a time. Running times over a 60 in. distance were computed by summing the alley and goal section times which were recorded on Standard Electric Timers connected to a 10 in. floor treadle and to two photocells located 48 in. and 60 in. beyond the treadle. When S passed the last photobeam, located
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