Avoidance learning to stimulus objects presented following shock
Abstract
An earlier informal experiment by Hudson (1950) in which rats learned to avoid a bundle
of pipe cleaners presented only following shock is replica.ted and extended. Five
groups of 20 Ss each received a single shock each while taking a sucrose pellet from
a novel striped panel, A black-out period ranging from 1 to 40 sec. began with the
onset of the 3/4 sec. shock. During the black-out the striped panel (forward-order
CS) was removed; immediately following the black-out, a rubber toy hedgehog descended
into the apparatus, Following a short exposure to the toy hedgehog and an intervening
24 hr. in the home cage, S was observed in the apparatus with the toy hedgehog at
one end and the striped panel at the other. Control groups received either shock without
the toy hedgehog or the toy hedgehog without the shock. All behavior was video recorded.
Significant differential avoidance of the toy hedgehog occurred in the short inter
stimulus interval groups (1, 5, and 10 sec.), but not in the 40 seCc group or in the
control groups. In further analyses, individual’s were classified as differentially
avoiding either the toy hedgehog, the striped panel, the shock location, the opposite
end of the apparatus or no identifiable stimulus, according to two schemes. In the
first, the basis
of classification was differences in time spent in a normal posture at the two ends
of the apparatus relative to a distribution of such differences in the unshocked control
group. In the other, a combined score derived from differences in four other classes
of behavior was the basis of classification. In both analyses, significant numbers
of Ss from the 1, 5, and 10 sec. groups were identified as avoiding the toy hedgehog,
while insignificant numbers of Ss from the 40 sec. and control groups did so. Only
insignificant numbers of Ss avoided the striped panel.
The results demonstrate that the "backward" association of the toy hedgehog with the
shock is a reliable and robust phenomenon that can occur
despite a 10 sec. UCS-CS delay, a single trial procedure, a 24-hr. delay between shock
and testing, and the availability of a potential forward -
order CS. The results cannot readily be explained either in terms of an unconditioned
response to the toy hedgehog or simple sensitization. Both
logical considerations and experimental results in backward conditioning preclude
describing these results in terms of stimulus cuing.
The results are interpreted as a. demonstration of the ability of rats to perceive
causal agent-effect relationships in certain specific situations. Support for conclusions
drawn from the inference that rats can make causal agent-effect connections is taken
from the areas of belongingness, stimulus selection in avoidance learning, delayed
taste -avoidance learning, novelty, reflexive aggression, and species-specific defense
reactions. Theoretical literature relevant to this inference and the broader question
of what is learned is discussed.
Description
This thesis was digitized as part of a project begun in 2014 to increase the number
of Duke psychology theses available online. The digitization project was spearheaded
by Ciara Healy.
Type
DissertationDepartment
PsychologyPermalink
https://hdl.handle.net/10161/13557Published Version (Please cite this version)
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