Abstract

BERMUDEZ, Karina A.  and  BRUNER, Carlos A.. The acquisition of lever-pressing by rats under degraded conditions of conditioned reinforcement. Acta comport. [online]. 2012, vol.20, n.1, pp.5-14. ISSN 0188-8145.

There are few studies on the acquisition of new responses under degraded conditions of conditioned reinforcement. In this investigation the establishment and subsequent maintenance of a new response was studied with 21 rats directly exposed to a constant random-interval 7.5 s schedule for a 1-s light stimulus for leverpressing. Concurrently, the same stimulus and one food pellet were delivered independently of responding across the entire 32-minute sessions on a fixed-time 64 s schedule. For three rats each the stimulus and the delivery of food were separated by intervals of either 0, 1, 2, 4, 8, 16, or 32 s over consecutive blocks of 40 sessions. Although at low rates all rats lever-pressed even with intervals between the stimulus and food as long as 32 s. Response rates were progressively lower as the stimulus-food interval was lengthened, resembling a gradient of efficacy of conditioned reinforcement. Such finding is new to the literature on the acquisition of new responses with conditioned reinforcement.

Keywords : acquisition; conditioned reinforcement; rats; lever-pressing; conditioned-primary reinforcement intervals.

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