Overtraining in classical conditioning: A comparison of motor and cardiac systems in dogs

Data from the analysis of the Overlearning Reversal Effect (ORE) noted in a simultaneous, visual discrimination task, and the lack of this effect in a position habit discrimination, led to the prediction that the ORE would not be noted in classical conditioning. It was further noted that very little work on discrimination learning had been reported in Pavlovian conditioning. The idea of schizokinesis, as observed by Gantt and others in classical conditioning, has been elaborated using the simple conditioning paradigm, and no data were available to test whether this same split would occur on a more complex level of conditioning, such as a discrimination task. To test these ideas, nine dogs were trained to a criterion of minimum discrimination, and then divided into three groups and given varying amounts of overtraining (OT). The discrimination task given the animal was to flex its paw during the CS+ signalling the onset of a brief shock. After the varying amounts of OT all groups were placed in extinction, followed by reversal training until each dog reached a criterion of minimum reversal. The results indicated 1) that the cardiac discrimination did not form before the motor discrimination; 2) extinction of differentiation was not significantly affected by the amount of OT given; 3) the mean level of responding in the motor system during extinction was highly correlated with the mean level of responding during the initial discrimination training; 4) OT had no effect on the speed of reversal of either the motor or the cardiac systems; 5) the speed of reversal learning in the motor system was highly correlated with the speed of initial discrimination.     

Effect of manipulating the risetime of an acoustic stimulus on two protective reflexes: cardiac defense and motor startle

Effect of manipulating the risetime of an acoustic stimulus on two protective reflexes: cardiac defense and motor startle. The risetime is a parametric characteristic of the eliciting stimulus frequently used to differentiate among psychophysiological reflexes. The aim of the present study was to examine the effect of manipulating the risetime of an acoustic stimulus on two protective reflexes: cardiac defense and motor startle. 100 participants underwent a psychophysiological reactivity test to five presentations of an intense acoustic stimulus (105 dB white noise) under one of five risetime conditions: 0, 24, 48, 96, and 240 ms. Total energy of the stimulus was controlled by increasing the base duration of the stimulus (1000 ms) by one third of the risetime. Results showed that risetime significantly affected motor startle but not cardiac defense. Startle amplitude decreased linearly with increasing risetime after 24 ms. On the other hand, repetition of the stimulus significantly affected cardiac defense but not motor startle. These results question the traditional differentiation between startle and defense based on risetime.     

The role of gross locomotor restriction in the acquisition of motor and cardiac conditional discrimination in the dog

The effects of gross locomotor restriction and lack of restriction, respectively, on the acquisition of a motor and cardiac discrimination task was investigated. Litter-mate dogs were used in a counterbalanced design involving two treatment conditions (free and restrained) and two discrimination learning problems. Each learning problem included eight daily training sessions with 10 CS+ tones and ten CS—tones presented randomly. The US was a shock to the left foreleg. Degree of foot flexion and percentage change in heart rate in response to CS tones were recorded. Dogs subjected initially to the free condition manifested a superior and more rapid motor and cardiac discrimination than Ss initially restrained. The free condition was not as facilitatory when presented to Ss which first had been exposed to the restraint condition. The results are discussed in terms of activation and negative transfer.     

A comparison of classical eyelid conditioning in adults and infants

In a classical conditioning procedure an eyeblink-eliciting tap to the glabella (the flat region of skin between the eyebrows) was presented 500 ms after the onset of a mild l-kHz tone. As tone-tap presentations proceeded, the probability of an eyeblink during the latter part of the tone increased in both infants (median age 8 months) and adults, but the infants were slower to condition than the adults and were more variable. Overall, the latency of the conditioned response to tone was significantly longer for infants than for adults, but the latency of the unconditioned response to tap was significantly shorter for infants than for adults.     

Classical skin conductance response conditioning: effects of intermittent reinforcement and information about schedule contingencies.

Skin conductance responses were differentially conditioned using reinforcement schedules of 25%, 50%, 75%, and 100%, manipulated between subjects. Half of the subjects were informed about schedule contingencies, and half were uninformed. The interstimulus interval was 6 sec. Discrimination of first-interval responses (1.0-3.5 sec after conditioned stimulus [CS] onset) by informed subjects did not vary with the ratio variable, but that by uninformed subjects improved with increasing reinforcement ratio because of diminished response levels to the nonreinforced CS (CS-). Discrimination of second-interval responses (3.6-7.0 sec after CS onset) improved as a function of increasing reinforcement ratio because of elevated response levels to the reinforced CS (CS+), but the effect was not persistent across trials in informed subjects. Performance in the first and second intervals did not reflect sequential increments and decrements as a function of reinforced and nonreinforced trials. Third-interval responses (7.1-9.9 sec after CS on nonreinforced trials) were not affected by schedule manipulations, but unconditioned responses diminished with increasing reinforcement ratio. Information about schedule contingencies led to superior discrimination of first-, second-, and third-interval responses and to suppression of unconditioned responses.     

A comparison of escape and avoidance conditioning in wild and domesticated rats

In the first of two experiments, three cotton rats (Sigmodon hispidus) and three albino rats were exposed to instrumental escape, unsignaled avoidance, and signaled avoidance, in that order. All subjects learned the escape procedure quickly, with the albino rats having generally shorter latencies, higher response rates, and requiring fewer sessions to reach the criterion. When the avoidance contingency was introduced, the cotton rats continued to respond almost entirely in the presence of the shock, whereas the albino rats responded in its absence, thus displaying effective avoidance behavior. Introduction of a pre-aversive stimulus did not improve the performance of the cotton rats. In the second experiment, five cotton rats and four albino rats were exposed to a free-operant (Sidman) avoidance procedure with a shock-shock interval of 3 sec and a response-shock interval of 20 sec. The cotton rats initiated responding at lower shock intensities than the albino rats, but their asymptotic avoidance responding was far less effective.     

Classical eyeblink conditioning in adulthood: effects of age and interstimulus interval on acquisition in the trace paradigm

Effects of age and interstimulus interval (ISI) were examined in eyeblink classical conditioning with a trace paradigm. Sixty young adults were trained in Experiment 1 with 6 interstimulus intervals (ISIs): 400, 900, 1,200, 1,500, 1,800, and 2,100 ms. The purpose was to find an ISI value for humans that would result in nonoptimal acquisition. ISIs of 1,200 ms and longer were nonoptimal. Adults aged 17-81 years were trained in Experiment 2 with a nonoptimal 1,800-ms ISI in the trace paradigm. Young and middle-aged subjects demonstrated equivalent levels of acquisition, and only older subjects conditioned more poorly. Aging appears to affect conditioning in the long-ISI trace paradigm as well as in the short-ISI delay paradigm.     

Classical heart-rate conditioning in the rat: The influence of curare and various setting operations

Conflicting reports concerning the success of classical conditioning of heart rate (HR) in curarized animals led to an experiment using a transfer design in which rats were classically conditioned either under curarized or restrained conditions. These conditions were then reversed for each group, giving a Curarized-Restrained (C-R) and a Restrained-Curarized (R-C) group. Results indicated that curare inhibits the conditional and unconditional HR response both during initial acquisition and after asymptotic levels of a HR CR have been attained. In addition, the C-R group did not acquire a CR during their later non-curarized restrained conditioning sessions, implying an inhibitory transfer from their earlier conditioning under curare. The UCRs during this period were normal for restrained rats. Analogous experimental“setting operations” prior to restrained conditioning were then explored by a second experiment which attempted to replicate the inhibitory transfer effect. The experimental operations investigated included: (1) restrained conditioning to investigate conditioned inhibition possibilities; (2) pseudo-conditioning types of randomized CS and UCS non-paired presentations to investigate associative vs. non-associative explanations; (3) CS-Only presentations to investigate possibilities that curare creates a blockage to the UCS, thus creating an inhibiting habituation to the CS; and (4) a group receiving curarization sessions, but no conditioning, to test the drug-only transfer effects. Results from the first and second experiments together indicated no inhibitory transfer effects under any prior experimental conditions except for those animals receiving classical conditioning while curarized. Only the CS-O group demonstrated any other kind of significant transfer effect; in this case a positive transfer accelerating later conditioning due to prior CS habituation sessions. These findings were discussed within the context of existing reports of curarized conditioning and setting operation effects on later conditioning, and various potential explanations and interpretations were explored.     

Predicting belief in paranormal phenomena: a comparison of conditional and probabilistic reasoning

Previous studies, using student participants, have investigated conditional reasoning (Wierzbicki, 1985) and probabilistic reasoning (Blackmore and Troscianko, 1985) separately as predictors of belief in paranormal phenomena. Findings show that the fewer reasoning errors made, the less likely people are to believe. The current study investigated both types of reasoning within the same analysis in order to find the extent to which each would predict paranormal belief by itself. Sixty‐five non‐undergraduate participants completed two self‐report questionnaires to ascertain their degree of belief in the paranormal, and a reasoning test. The expected negative correlation between reasoning ability and paranormal belief was found. However, while conditional reasoning scores predicted paranormal belief (r=−0.27), probabilistic reasoning scores did not (r=0.01). It was noted that the sample used was possibly biased, due to a lack of sufficiently sceptical participants, and that future studies may need to target people with different degrees of belief. Copyright © 1999 John Wiley & Sons, Ltd.