Date of Award:
Doctor of Philosophy (PhD)
J. Grayson Osborne
Six experiments were run to determine whether the duration of conditioned defensive burying (COB) in rats is a function of its consequences.
Four experiments developed the methodology. Experiment 1 replicated the standard one-trial experiment, where rats are shocked once by a prod. All three rats exhibited CDB. Experiment 2 used a lever-press-for-water contingency to force recontact with the lever, following shock deliveries in Sessions 6 and 14. All three rats buried the lever in both sessions. Experiment 3 replicated Experiment 2, employing albino and hooded rats. All six buried the lever. The albinos exhibited longer burying durations. Experiment 4 used the lever-press-for-water contingency but employed extinction to test whether rats would bury the lever under that condition. They did not.
Experiment 5 used three groups of rats to determine whether burying durations are a function of CDB's consequences. Groups LS and LSH had enough sawdust to cover the lever, but a hole under the lever was opened during LSH's burying. Group SS lacked enough sawdust to cover the lever. The groups' mean burying durations (MBDs) were not significantly different in Session 6. Following Session 14, group differences and a group-by-session interaction were statistically significant. Effect sizes for Groups LS and SS were large. Group LS's MBD increased, Group LSH's remained unchanged, and Group SS's decreased.
Experiment 6 used two groups of rats to determine whether MBDs are a function of shock source visibility. Group C's substratum consisted of uncolored, transparent Plexiglas blocks. Group B had black, opaque blocks. Only the group-by-session interaction was statistically significant. The MBDs of Groups Band C paralleled those of Groups LS and SS in Experiment 5. The effect sizes for C and B were large and medium, respectively.
CDB occurred in all experiments where the rats received shocks, and CDB was reproduced in experiments where the animals were forced to recontact the shock source through a lever-press-for-water contingency.
CDB durations are a function of their consequences. Rats whose burying covers or blocks the shock source from view exhibit longer burying durations in succeeding shock trials. Rats whose burying is ineffective exhibit shorter durations.
Goldberg, Stephen Gregory, "Durational Control of Defensive Burying in Rats: An Investigation of a Species-Specific Defense Reaction" (1988). All Graduate Theses and Dissertations. 5977.
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