Learned helplessness: effects of response requirement and interval between treatment and testing.
Three experiments investigated learned helplessness in rats manipulating response requirements, shock duration, and intervals between treatment and testing. In Experiment 1, rats previously exposed to uncontrollable or no shocks were tested under one of four different contingencies of negative reinforcement: FR 1 or FR 2 escape contingency for running, and FR1 escape contingency for jumping (differing for the maximum shock duration of 10s or 30s). The results showed that the uncontrollable shocks produced a clear operant learning deficit (learned helplessness effect) only when the animals were tested under the jumping FR 1 escape contingency with 10-s max shock duration. Experiment 2 isolated of the effects of uncontrollability from shock exposure per se and showed that the escape deficit observed using the FR 1 escape jumping response (10-s shock duration) was produced by the uncontrollability of shock. Experiment 3 showed that using the FR 1 jumping escape contingency in the test, the learned helplessness effect was observed one, 14 or 28 days after treatment. These results suggest that running may not be an appropriate test for learned helplessness, and that many diverging results found in the literature might be accounted for by the confounding effects of respondent and operant contingencies present when running is required of rats.
Hunziker
M H L
MH
Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Prof. Mello Moraes 1721, CEP 05508-030 - Cidade Universitária - São Paulo, Brazil. hunziker@lexxa.com.br
Dos Santos
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CV
D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology; D004597:Electroshock; D006380:Helplessness, Learned; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology