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Reversal Learning in Rats. Susanne C. Stahl-Bell Mark S. Schmidt Columbus State University

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Reversal Learning in Rats

Susanne C. Stahl-Bell

Mark S. Schmidt

Columbus State University

Stahl-Bell, S., & Schmidt, M.S. (2002, April). Reversal learning in rats. Paper presented at the 1st annual Georgia Undergraduate Research in Psychology Conference, Kennesaw State University, Kennesaw, GA.


Successive Discrimination Reversal (SDR) Learning

  • A task in which animals must learn to reverse an operant response across successive problems.

  • With each reversal, fewer errors are made.


Original Problem

Correct response

Reversal

Correct response


Past Research

  • The SDR task has been used as a measure of animal intelligence by some researchers.

  • In one study it was shown that there were significant differences between species on the SDR task (Gossette, Kraus, and Speiss, 1968)


Species Differences

  • Gossette et al. used a spatial SDR task to compare the learning abilities of kinkajous, squirrel monkeys, coatis, skunks, raccoons, cacomistles, and capuchin monkeys.


Raccoon

Squirrel monkey

Coati Mundi

Cacomistle

Skunk

Kinkajou

Capuchin


Cumulative Errors Across 19 Reversals (Gossette et al. 1968)


A Previous Study with Rats

  • An earlier study by Dufort, Guttman, and Kimble (1953) studied SDR in rats.

  • All but one rat in their experiment were able to learn an SDR task to near perfect performance (1 error) per reversal.

  • However, the rats could have used visual cues in addition to spatial cues to solve the SDR task.


Our Study

  • We also wanted to study rats in a SDR task but where the stimuli were identical.

  • Our study was more like Gossette’s study because we used a spatial SDR task with identical visual stimuli.


Our Study

  • We hypothesized that our rats would not do as well as Dufort’s rats because our rats would not have distinctive visual cues in the stimuli.

  • We wanted to see where our rats would rank in Gossette’s hierarchy of species.

  • How smart is a rat compared with raccoons, monkeys, etc.?


Subjects

  • We used 8 male rats acquired from Harlan Sprague Dawley.

  • All were from the Dark Agouti (DA) strain, which is known to have superior vision.

  • The rats were approximately 3 months old and were food deprived for 48 hours prior to testing each day.


Apparatus

  • The stimuli were two identical white Styrofoam cups, 9.5 x 4.5 x 8 cm.

  • The cups were placed in distinct spatial locations (left-right) 31 cm apart on a table top, 100 cm from the edge of the table.


Procedure

  • On each trial the rat was released at the edge of the table and had to walk to the cups and move aside a cup to get a food pellet.


Procedure

  • Each reversal consisted blocks of 20 trials.

  • The rat was considered to have learned the reversal if he got 18/20 correct.

  • The rat had to complete each set of 20 trials, even if they got the first 18 responses correct.

  • The rats underwent a total of 15 reversals.


Results

  • The rats made significantly fewer errors across reversals as expected.


Mean Errors / Reversal

r = -.85

p < .01


Results

  • Mean cumulative errors increased at a slower rate than that seen in five of the seven species tested by Gossette et al. (1968)

  • By the 15th reversal our rats had accumulated about 100 errors.

  • Based on this comparison, our rats ranked between cacomistles and raccoons in spatial SDR performance.


Our Results Compared with Gossette’s


Cumulative Errors Across 19 Reversals (Gossette et al. 1968)

Our rats


Discussion

  • Gossette’s study as well as our study uses a quantitative approach to study animal behavior. This follows the older view that animals can be ranked in terms of intelligence for example by comparing how well they perform on a specific test and how many trials it takes to acquire the task. Using this approach, our rats were ranked in terms of intelligence between the raccoon and cacomistle.


Discussion

  • Because many problems have been pointed out by using the quantitative approach, most researchers today say that qualitative approaches to study animal behavior should be used.

  • It has been pointed out (Thomas, 19??) that quantitative approaches don’t take sensory differences, motor abilities, or motivational differences into account.


Subjects Not Used


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