Real-time factors in the rabbit’s nictitating membrane response to pulsed and serial conditioned stimuli

Abstract

Conditioning theories and recent real-time models commonly postulate that a reinforcer is signaled by aseries of stimuli. In both Pavlovian and operant procedures, serial stimuli have heen shown to control the likelihood and timing of responses over intervals of seconds and minutes. The present experiments were conducted to determine whether serial stimuli exercise similar effects over stimulus-reinforcer intervals in the order of hundreds of milliseconds. Such intervals typify those used in conditioning of the rabbit nictitating membrane response. A sequence of four tone pulses (50-100 msec) was used as the CS to assess the effectiveness of serial stimuli. After training with this CS, tests were conducted in which one or more of the pulses were removed. These perturbations of the sequence of stimuli over a 400-msec interval produced large deficits in CR likelihood and smaller alterations in CR timing. The results are discussed with respect to their implications for current real-time models of conditioning, and particularly with respect to their assumptions about the source of internal stimuli, rules for learning, and rules for generating CRs.

Summation and configuration between and within sensory modalities in classical conditioning of the rabbit

“…Previous examinations of generalization in the rabbit NM preparation have shown that some elements would be shared by the tone and noise stimuli (Kehoe & Napier, 1991). However, the light stimulus would share virtually no elements with the auditory stimuli Kehoe, Morrow, & Holt, 1984).…”

“…This inference, however, is contrary to other available data that tone and noise are readily distinguishable. First, there is only about 50 % generalization from tones to white noise (Kehoe & Napier, 1991). Second, the same tone and white noise used in this experiment have been used successfully in differential conditioning (Kehoe, Marshall-Goodell, & Gormezano, 1987).…”

On the origin of personal causal theories

“…In serial conditioning two predictive cues are also offset in time, but both are present on all trials (A-7B+, where -7 indicates "is followed by"). This paradigm has been most vigorously pursued by Kehoe and his colleagues (Kehoe et al, 1993;Kehoe, Marshall-Goodell, & Gormezano, 1987;Kehoe & Napier, 1991;Kehoe, Schreurs, & Graham, 1987). The use of two sequential predictors is analogous to the presence of a simple causal chain, in which each event causes the next.…”

“…To the extent that these theories are rooted in an individual's personal experience, we may effectively argue that these processes are similar to those of a nonhuman subject. Animals do encode the expected temporal interval between CS onset/ offset and US onset (see, e.g., Kehoe, Horne, Macrae, & Horne, 1993;Kehoe & Napier, 1991). Sufficiency ofcontiguity.…”

Effect of varying the intensity and train frequency of forelimb and cerebellar mossy fiber conditioned stimuli on the latency of conditioned eye-blink responses in decerebrate ferrets.

“…Changes in CS frequency can then be interpreted as a test of generalization between two closely related CSs. This is indicated by experiments where test trials with increased CS tone frequency decreased the likelihood of a CR but not the CR latency (Kehoe and Napier 1991). We tested the effect of increasing the frequency of the CS train from 50 to 100 Hz in 13 animals.…”