Degree Name

Master of Arts (MA)

Semester of Degree Completion

1976

Thesis Director

William P. McGown

Abstract

Ninety-six male albino rats were housed from weaning in groups of 4, 8, or 16 animals. For all group sizes, animals were housed either in cages of a constant size (crowding) or in cages with floor space proportional to group size (density). Six animals from each of these conditions were tested for learning after either 55 or 109 days on a straight alley, a Lashley III maze, and a Y-maze. On the straight alley, no significant differences in running speed were found between durations, crowding and density, or group size. A significant trials effect was obtained (F=63.28, df=15/900, p < .01). On the Lashley III, a significant trials effect was obtained for running speed (F=102.27, df=8/480, p < .01) and errors (F=63.80, df=8/480, p < .01). The duration comparison showed the 55 day group making significantly more errors than the 109 day group (F=5.36, df=1/60, p < .05). No significant differences were found on running speed or errors between crowding and density or group size. On the Y-maze, the 55 day group had significantly more avoidances than the 109 day group (F=6.47, df=1/60, p < .05). The density groups took significantly fewer trials to reach criterion (F=4.44, df=1/60, p < .05) and a greater percentage of correct responses (F=4.48, df=1/60, p < .05) than the 109 day group. The results were discussed in terms of methodological inconsistency and the distinction between density and crowding.

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