Imagery in human classical conditioning.

Many clinical strategies use patients' imagery to explore and treat phobic and posttrauma reactions, however little attention has been paid to the underlying assumption that imagery of relevant stimuli may help maintain conditioned behavior. In this article, the authors examine the premise that mental images can potentiate and substitute for physical stimuli in human classical conditioning. The authors review empirical evidence to detail the role of images of conditioned stimuli (CS) and unconditioned stimuli (US) during pre-exposure to stimuli, the actual pairing of the CS and US, and extinction when the CS is presented alone. The evidence suggests that mental imagery can facilitate or diminish the outcome of classical conditioning in humans and, more tentatively, that mental images can substitute for actual US and CS in autonomic conditioning. They argue that researchers should explore the role of mental imagery in conditioning through the use of advances in the measurement of imagery. Finally, they analyze anxiety and trauma reactions as examples of how applied areas can be used to explore and benefit from developments in this area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A model of hippocampal learning during classical conditioning.

During classical conditioning of the rabbit blink reflex, a large fraction of the hippocampal pyramidal neurons are recruited to respond to the conditioned stimulus (CS). The summed response of these neurons comes to match the whole time-amplitude profile of nictitating membrane movement, whereas some individual neurons respond only to part of this profile. A model is proposed that includes a learning rule to explain neuron recruitment and that uses a tapped delay line to account for the temporal learning properties of the system and the spectrum of individual unit responses. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus compounding in free-operant and classical conditioning: A review and analysis.

Reviews previous free-operant and classical conditioning studies reporting additive summation, suppressive summation, and response averaging to compounded stimuli. A stimulus control model applicable to additive and suppressive summation in both paradigms is presented. A symmetrical composite-stimulus continuum, defined by the on-off states of the discriminative or conditioned stimuli controlling behavior in training, is seen to be common to both types of summation, with the functions of the all-on and all-off continuum extremes interchangeable. Moreover, additive summation, suppressive summation, and response averaging appear to be (a) dependent on discrimination training; and (b) determined by the history of, and immediate relations between, response outputs and reinforcement densities conditioned to particular stimulus values along the composite training dimension. This evidence and the derived stimulus control model are used to functionally relate summation to generalization peak shift. It is suggested that these additive, suppressive, and averaging effects to compounded stimuli might further help in clarifying, and in placing in contextual perspective, what are currently thought of as "excitatory" and "inhibitory" mechanisms in learning. (72 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of contingency in classical conditioning.

The assumption that classical conditioning depends on a contingent relation between the conditioned stimulus (CS) and the unconditioned stimulus (US), which was proposed some decades ago as an alternative to the traditional contiguity assumption, still is widely accepted as an empirical generalization, if no longer as a theoretical postulate. The first support for the contingency assumption was provided by experiments in which occasional CS–US pairings produced no response to the CS in random training—i.e., training in which the probability of the US was the same in the presence and absence of the CS. Those early experiments, the results of which too often are taken at face value, are reconsidered along with various later experiments that show conditioning, both of the CS and its context, in random training. The evidence suggests that CS–US contingency is neither necessary nor sufficient for conditioning and that the concept has long outlived any usefulness it may once have had in the analysis of conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attitudes established by classical conditioning.

"2 experiments were conducted to test the hypothesis that attitude responses elicited by a word can be conditioned to a contiguously presented socially significant verbal stimulus… . In Experiment I, one national name was paired with positive evaluative meaning and another was paired with negative evaluative meaning. In Experiment II, familiar masculine names were used. In each experiment there was significant evidence that meaning responses had been conditioned to the names without Ss' awareness." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of timing and classical conditioning.

Four experiments with 63 Charles River and Sprague-Dawley rats investigated whether the timing of a stimulus (sound) correlated with the strength of a CR to the stimulus. The timing (effective duration) of the stimulus was measured with the peak procedure, similar to a discrete-trials, fixed-interval procedure. Ss were trained so that their response rate reached a maximum at approximately 40–60 sec after the onset of a light; the time of the maximum measured from the start of the light (peak time) was the measure of timing. On some trials, the light was preceded by a short (5-sec) or long (20- or 30-sec) interval of sound. It was assumed that the difference in peak time after long and short sounds reflected the timing of the sound: If the sound was timed, the longer sound would produce a lower peak time; if the sound was not timed, the 2 durations of sound would produce the same peak time. The CR was leverpressing during the sound. The sound was treated in various ways: presented alone (Exps I, III, and IV), followed by food (Exps I, III, and IV), preceded by food (Exp III), and followed by food after 20-sec (Exp IV). Treatments that produced no timing of sound produced no CR, and treatments that increased (or decreased) timing also increased (or decreased) the CR. Findings suggest that there is overlap between the mechanisms that produce time discrimination and the mechanisms that produce classical conditioning. (41 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Stimulus and temporal cues in classical conditioning.

In 2 experiments, separate groups of rats were given stimulus conditioning, temporal conditioning, untreated control and (in Experiment 2) learned irrelevance control procedures followed by a compound with both stimulus and temporal cues. Stimulus conditioning consisted of a random 15-s duration conditioned stimulus (CS) followed by food; temporal conditioning consisted of food–food intervals of fixed 90 s (Experiment 1) or fixed 75?+?random 15 s (Experiment 2). The stimulus group abruptly increased responding after CS onset, and the temporal group gradually increased responding over the food–food interval. When the food–food interval was fixed 90 s, the temporal cue exerted stronger control in the compound, whereas when the food–food interval was fixed 75?+?random 15 s, the stimulus cue exerted stronger control. The strength of conditioning, temporal gradients of responding, and cue competition effects appear to reflect simultaneous timing of multiple intervals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Consolidation disruption and inhibition in classical conditioning.

Discusses implications of posttrial consolidation of the memory trace for classical conditioning theory, and explores similarities and differences between consolidation-process disruption and existing concepts of inhibition. Experimental designs are proposed and discussed in relation to the operational requirements for demonstration of consolidation-process disruption. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eyeblink classical conditioning in the preweanling lamb.

Classical conditioning of eyeblink responses has been one of the most important models for studying the neurobiology of learning, with many comparative, ontogenetic, and clinical applications. The current study reports the development of procedures to conduct eyeblink conditioning in preweanling lambs and demonstrates successful conditioning using these procedures. These methods will permit application of eyeblink conditioning procedures in the analysis of functional correlates of cerebellar damage in a sheep model of fetal alcohol spectrum disorders, which has significant advantages over more common laboratory rodent models. Because sheep have been widely used for studies of pathogenesis and mechanisms of injury with many different prenatal or perinatal physiological insults, eyeblink conditioning can provide a well-studied method to assess postnatal behavioral outcomes, which heretofore have not typically been pursued with ovine models of developmental insults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebellar involvement in eyeblink classical conditioning in humans.

The role of the ipsilateral cerebellum in human eyeblink conditioning was investigated using the 400-ms delay paradigm and testing 14 cerebellar patients (7 with unilateral lesions and 7 with bilateral lesions) and 20 control participants. Patients performed significantly worse with the ipsilesional eye than control participants but showed no difference when tested with the contralesional eye. Conditioned responses (CRs) totaled 14% for all patients in comparison with 60% for control participants. Data on timed-interval tapping for 6 patients and 14 control participants showed that clock variability was greater with the ipsilesional hand in patients. Only clock variability correlated significantly with percentage of CRs in control participants. Comparisons of paired associate learning and memory for 8 patients and 14 control participants revealed no significant differences. Results confirm that the ipsilateral cerebellum plays a role in eyeblink classical conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

UCS intensity and instructional set in classical eyelid conditioning: Discrimination conditioning and signal-detection analysis.

Conducted discrimination eyelid conditioning at 2 UCS intensities under inhibitory, neutral, and facilitatory instructional sets, in a experiment involving 144 undergraduates in 6 groups. Instructional set yielded receiver operating characteristic curves that were reasonably straight lines on a normal deviate plot. The tentative conclusion from signal-detection theory of an equal discriminability function across instructional sets was contrasted with 4 indices of discrimination, indicating significant but mutually contradictory changes in discrimination as a function of instructional set. Discrimination differences were produced by UCS intensity, particularly under the neutral instructions. (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Induction of prestige suggestion through classical conditioning.

2 experiments are reported. Exp. I was a successful replication of a study by Staats & Staats in which implicit responses to evaluative words were conditioned to nonsense syllables. Exp. II was an extension of this paradigm to prestige suggestion. The hypothesis tested was that implicit responses to prestigeful famous and infamous names could be conditioned to relatively meaningless stimuli, nonsense syllables. In the latter experiment, a nonsense syllable was presented on a screen 18 times, each time paired with the auditory with the auditory presentation of a different name. While each name was different, they all had a common evaluative meaning component. There was significant evidence that evaluative meaning responses were conditioned to the syllables without S's awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional and error-correcting associative mechanisms in classical conditioning.

R. A. Rescorla (2000, Rescorla, 2001, Rescorla, 2002) reported that the associative changes undergone by 2 conditioned stimuli that are reinforced or not reinforced in compound depend on their initial associations. The results contradict the predictions of simple error-correction models but can be explained by models that incorporate a “constrained” error-correction rule. A model of classical conditioning presented by N. A. Schmajuk, Y. Lam, and J. A. Gray (1996) suggests that attentional mechanisms, acting during both compound training and testing, have an important role in producing those results. Moreover, the model suggests that those attentional mechanisms might obscure the evaluation of the associative changes undergone by the conditioned stimuli during compound training. Two experiments that differentiate our model from competing theories are proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eyeblink classical conditioning in H. M.: Delay and trace paradigms.

H.M., a well-known S with bilateral removal of medial-temporal-lobe structures and profound amnesia, performed eyeblink classical conditioning (EBCC) for 21 90-trial sessions in the 400-msec delay and 900-msec trace paradigms. A 2nd amnesic S with temporal lobe lesions and 2 normal control Ss (NCSs) were also conditioned. Acquisition occurred in both paradigms for all Ss. Acquisition in the delay paradigm was prolonged in H.M. (perhaps because of his cerebellar degeneration in the vermis and hemispheres), but not in the 2nd amnesic S. Amnesic Ss and NCSs showed more rapid acquisition in the trace than in the delay paradigm. Two years after initial EBCC, H.M. attained learning criterion in the trace paradigm in 1/10th as many trials. No recollection of the experimenters, apparatus, instructions, or procedure was manifested by H.M. Results suggest that humans can condition in the 400-msec delay and 900-msec trace EBCC paradigms with the hippocampus radically excised. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hyperstriatal lesions and classical conditioning in the pigeon.

In two experiments, pigeons with bilateral lesions of the hyperstriatum were compared with unoperated control birds and operated control subjects having bilateral lesions of the neostriatum on tasks designed to test two hypotheses of hyperstriatal function. In Experiment 1, hyperstriatal lesions impaired both the acquisition and maintenance of autoshaped responding as well as maintenance responding in response-omission training. In Experiment 2, hyperstriatal birds displayed depressed levels of responding relative to control birds on a classical go-no-go alternation schedule. These results support the view that hyperstriatal lesions selectively disrupt classical conditioning and go against the view that hyperstriatal lesions exaggerate perseverative responding. A surprising aspect of the results was the performance of the operated control subjects that showed better performance in the acquisition of autoshaping and superior differentiation on the go-no-go schedule compared with the unoperated control birds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact delay-eyeblink classical conditioning in amnesia

The status of classical conditioning in human amnesia was examined by comparing conditioning of the eyeblink response (the unconditional response) to a tone conditioned stimulus (CS) paired with an airpuff unconditioned stimulus (US) in the delay paradigm between 7 amnesic and 7 age- and education-matched normal control participants. Amnesic patients exhibited normal baseline performance in pseudoconditioning and normal acquisition and extinction of conditioned responses in terms of the number, latency, and magnitude of eyeblinks. These results indicate that in humans, as in rabbits, brain structures critical for declarative memory are not essential for the acquisition of elementary CS-US associations.     

Effect of classical conditioning on an internal clock.

Six experiments with 53 male Charles River rats used a psychophysical choice procedure to study the internal clock used to discriminate duration and to investigate whether this clock is sensitive to the signal value (associative strength) of a stimulus. The experiments involved 2 types of trials: On choice trials, a stimulus lasted a short (e.g., 3-sec) or long (e.g., 12-sec) duration; Ss then chose between 2 levers. The rewarded choice depended on the duration of the stimulus. On conditioning trials, the stimulus used on choice trials was presented, but it ended without food (extinction trials) or with food (pairing trials) regardless of what the S did. The main measure of performance was short bias, defined as accuracy with the short stimulus without a corresponding accuracy with the long stimulus. Exp I showed that extinction trials increased short bias relative to training without conditioning trials or to training with pairing trials. Exps II–VI tested explanations of these results. The same results were found when extinction trials were the same duration as the short stimulus (Exp II), when extinction trials were a random duration (Exp V), and when the signal value of the CS was changed in another way (Exp VI). The effect of conditioning trials was modality specific (Exps III and IV). It is concluded that, of the explanations considered, the most valid is that changing the signal value of a stimulus changes how the clock times the stimulus. Reducing signal value reduces the measured duration. (54 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Scopolamine disruption of septo-hippocampal activity and classical conditioning.

Sixteen New Zealand White rabbits were implanted with multiple-unit recording electrodes in the hippocampus and lateral septum. Animals received either scopolamine hydrobromide (HBr) or scopolamine methylbromide (MBr, 1.5 mg/kg sc) prior to nictitating membrane conditioning. Slow wave analysis indicated that HBr reduced 5- to 8-Hz and increased 9- to 12-Hz hippocampal activity and increased 1- to 4-Hz activity in both hippocampus and lateral septum. Integrated unit activity from the HBr group showed suppression of responses in septum and hippocampus during learning, whereas the MBr group developed conditioned responses (CRs) in both structures. Behavioral findings indicated that HBr took longer to reach criterion (M?=?329.5?±?45.3) than MBr (M?=?120.2?±?16.0). This experiment showed that centrally active anticholinergic drugs alter the patterns of neuronal activity in the septo-hippocampal region that predict and accompany normal learning. Such drugs delay behavioral acquisition as well, a result suggesting a modulatory role for this brain system in the acquisition phase of classical conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebellar stimulation as an unconditioned stimulus in classical conditioning.

Implanted rabbits with chronic stimulating electrodes in white matter underlying lobule HVI of the cerebellar cortex. Stimulation elicited movements of the face or neck and, when paired with a tone CS, produced learning comparable to that seen with peripheral unconditioned stimulus/stimuli (UCS). CS-alone trials produced extinction. Reinstatement of paired trials produced reacquisition with savings. Additional groups received either explicitly or randomly unpaired CS–UCS trials before paired conditioning. Low-frequency responding during these sessions indicated that the paired training results were associative and not due to pseudoconditioning or sensitization. Explicitly unpaired sessions retarded learning on subsequent paired trials compared with groups that received either randomly unpaired or no CS–UCS preexposure. These results are interpreted in terms of the role of the cerebellum and associated pathways in classical conditioning of motor responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A theoretical and empirical integration of the rational-emotive and classical conditioning theories.

Tested the assumptions of A. Ellis's ABC theory of psychopathology, which relates implicit verbalizations to emotional arousal. The theory is recast in a developmental conditioning framework which becomes the basis for criticism of a previous study by D. C. Rimm and S. G. Litvak (see record 1969-09037-001) of these assumptions. An empirical replication and extension was conducted, in which 5 hypotheses were derived and tested, using 40 female undergraduates as Ss. Sentence dyads, relevance of content, and neuroticism were manipulated. Response measures were galvanic skin conductance, respiration rate, and respiration depth. Only the galvanic skin response (GSR) measure differentiated the responses of the experimental Ss (with emotionally loaded stimuli) from those of control Ss (with neutral stimuli). The ABC theory was supported by the GSR measure on 3 of the 5 hypotheses under investigation. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)