Electrodermal Conditioning Research Articles

Fear Conditioning Deficits in Children and Adolescents with Psychopathic Traits: a Study in a Clinical Population

Deficits in fear conditioning related to psychopathy have been widely studied in adults. However, evidence in children and adolescents is scarce and inconsistent. This research aimed to expand knowledge about fear conditioning in psychopathy and its dimensions in child and early adolescent clinical populations. Participants were 45 boys (outpatients) aged 6–14 years (M = 10.59, SD = 2.04). They were assessed with the parents’ and teachers’ versions of the Child Problematic Traits Inventory (CPTI). A fear conditioning paradigm (Neumann et al., in Biological Psychology, 79(3), 337–342, 2008) for children and adolescents was used. Conditioned stimuli (CS+ and CS-) were geometric shapes and the unconditioned stimulus (US) was an unpleasant sound of metal scraping on slate (83 dB). Difference scores (CS+ minus CS-) in skin conductance responses (SCR) and self-reported cognitive and affective measures were considered as indices of fear conditioning. Results showed that: a) deficits in fear conditioning were related to some psychopathy dimensions but not to psychopathy as a unitary construct; b) the Impulsivity-Need for Stimulation dimension was a predictor of impaired fear conditioning at a cognitive level; c) the interaction of Callous-Unemotional and Impulsivity-Need for Stimulation dimensions was a significant predictor of impaired electrodermal fear conditioning; d) by contrast, the Grandiose-Deceitful dimension, was marginally associated with a greater electrodermal fear conditioning. In conclusion, psychopathy dimensions and their interactions, but not psychopathy as a whole, predicted deficits in fear conditioning as measured by SCR and cognitive indices. These findings confirm the notion that psychopathic traits are associated with deficits in fear conditioning in child and adolescent clinical populations and provide support for a multidimensional approach to youth psychopathy.

Concurrent Electrodermal and Eyeblink Conditioning With Masked and Unmasked Stimuli

Abstract. The aim of this study was to determine if contingency awareness between the conditioned (CS) and unconditioned stimulus (US) is necessary for concurrent electrodermal and eyeblink conditioning to masked stimuli. An angry woman’s face (CS+) and a fearful face (CS−) were presented for 23 milliseconds (ms) and followed by a neutral face as a mask. A 98 dB noise burst (US) was administered 477 ms after CS+ offset to elicit both electrodermal and eyeblink responses. For the unmasking conditioning a 176 ms blank screen was inserted between the CS and the mask. Contingency awareness was assessed using trial-by-trial ratings of US-expectancy in a post-conditioning phase. The results showed acquisition of differential electrodermal and eyeblink conditioning in aware, but not in unaware participants. Acquisition of differential eyeblink conditioning required more trials than electrodermal conditioning. These results provided strong evidence of the causal role of contingency awareness on differential eyeblink and electrodermal conditioning.

Dissociating conscious expectancies from automatic-link formation in an electrodermal conditioning paradigm.

The key point of a paradigm initially proposed by Perruchet (Pavlov J Biol Sci 20:163-170, 1985) to dissociate conscious expectancies from automatic-link formation in classical conditioning settings is the use of a partial reinforcement schedule, in which the unconditioned stimulus (US) follows the conditioned stimulus (CS) only half of the time on average. Given (pseudo) randomization, the whole sequence comprises runs of CS alone and runs of CS-US pairs of various lengths. When the preceding run goes from a long sequence of CS alone to a long sequence of CS-US pairs (via shorter sequences), associative strength should grow up, whereas conscious expectancy should decrease. Earlier studies have shown that, in most cases, conditioned performance parallels associative strength. As an exception, however, a few reports suggest that conditioned electrodermal responses (EDRs) would follow predicted changes in US expectancies. This paper presents an experiment that replicates this outcome. However, when the performances from a control group were taken as a baseline to control for response habituation, corrected conditioned EDRs were shown to follow associative strength. This suggests that the atypical pattern of conditioned EDRs in the Perruchet paradigm would be due to the fact that EDRs are more sensitive to habituation than responses involved in other associative learning settings. These results further challenge the recent "propositional" view of conditioning, which stipulates that conditioned responses in humans are the consequence of participants' conscious inferences about the relationships between the CS and the US, which would lead the CS to generate conscious expectancy for the US.

Dissociating expectancy of shock and changes in skin conductance: An investigation of the Perruchet effect using an electrodermal paradigm.

Is human Pavlovian conditioning driven by a unitary, propositional system (as claimed by Mitchell, De Houwer, & Lovibond, 2009) or by dual systems; one under conscious control, symbolic in nature, and requiring effort to deploy, and the other utilizing associative processes and automatic in its operation (McLaren, Green, & Mackintosh, 1994)? Past research has suggested that for electrodermal conditioning to occur in humans, conscious awareness of the contingencies is necessary to produce conditioned responding (e.g., Hinchy, Lovibond, & Ter-Horst, 1995), as predicted by single process theories that attribute the conditioned response (CR) to conscious expectancy of the shock. In this article, the authors examined the Perruchet effect (Perruchet, 1985), using an electrodermal paradigm to determine whether there is any role for associative processes in human electrodermal conditioning. The authors attempted to replicate the basic effect, whereby expectancy of an unconditioned stimulus (US) increases over a run of nonreinforced trials while the CR to the conditional stimulus (CS) declines, and the complementary pattern in which expectancy decreases over a run of reinforced trials while the CR to the CS grows in strength. In line with these patterns, the change in skin conductance response (our CR) as a function of US run length was found to follow a linear trend opposite to that of conscious expectancy of shock with respect to US run length. This dissociation supports a dual-processing system account of human Pavlovian conditioning, with conscious, controlled processes governing expectancy (and subject to the gambler's fallacy), whereas automatic, associative processes determine at least some of the strength of the CR to the CS.

Insensitivity to stimulus validity in human Pavlovian conditioning.

Four experiments investigated the role of information value, or stimulus validity, in human electrodermal conditioning. Conditioned stimuli (CSs) were long, variable duration (10-50-sec) slides or ...

Backward and forward blocking in human electrodermal conditioning: blocking requires an assumption of outcome additivity.

Blocking was observed in two human Pavlovian conditioning studies in which colour cues signalled shock. Both forward (Experiment 1) and backward (Experiment 2) blocking was demonstrated, but only when prior verbal and written instructions suggested that if two signals of shock (A+ and B+) were presented together, a double shock would result (AB++). In this case, participants could assume that the outcome magnitude was additive. Participants given non-additivity instructions (A+ and B+ combined would result in the same outcome, a single shock) failed to show blocking. Modifications required for associative models of learning, and normative statistical accounts of causal induction, to account for the impact of additivity instructions on the blocking effect, are discussed. It is argued that the blocking shown in the present experiments resulted from the operation, not of an error-correction learning rule, nor of a simple contingency detection mechanism, but of a more complex inferential process based on propositional knowledge. Consistent with the present data, blocking is a logical outcome of an A+/AB+ design only if participants can assume that outcomes will be additive.

Probing the Time Course of Nonlinear Discriminations during Human Electrodermal Conditioning

Animal-based theories of Pavlovian conditioning propose that patterning discriminations are solved using unique cues or immediate configuring. Recent studies with humans, however, provided evidence that in positive and negative patterning two different rules are utilized. The present experiment was designed to provide further support for this proposal by tracking the time course of the allocation of cognitive resources. One group was trained in a positive patterning schedule (A−, B−, AB+) and a second in a negative patterning schedule (A+, B+, AB−). Electrodermal responses and secondary task probe reaction time were measured. In negative patterning, reaction times were slower during reinforced stimuli than during nonreinforced stimuli at both probe positions while there were no differences in positive patterning. These results support the assumption that negative patterning is solved using a rule that is more complex and requires more resources than does the rule employed to solve positive patterning.

Evidence for the application of rules in Pavlovian electrodermal conditioning with humans

Two Pavlovian SCR conditioning experiments investigated interference effects in sequential training of positive and negative patterning discriminations in humans. In Experiment 1, positive patterning (A−, B−, AB+) was trained in Phase 1, immediately followed by a negative patterning schedule (C+, D+, CD−). We predicted that human participants would learn a specific numerosity rule in positive patterning, which interferes with the subsequent negative patterning schedule. In Experiment 2, negative patterning (C+, D+, CD−) was trained in Phase 1, followed by a positive patterning schedule (A−, B−, AB+) in Phase 2. Because human participants would learn an abstract ‘separate-versus-together’- or ‘opposite’-rule to solve the negative patterning discrimination in Phase 1, there should be less interference in positive patterning in Phase 2 where the separate/together-rule could be applied, too. In both experiments, the initial patterning discriminations were acquired successfully. In Experiment 1, human participants totally failed to solve the Phase 2 discrimination, while in Experiment 2 appropriate response differentiation developed in Phase 2. Thus, without pre-experience human participants seem to utilize a specific numerosity-rule in positive patterning and a separate/together-rule in negative patterning.

Relation between conditioned stimulus-elicit responses and unconditioned response diminution in long-interval human heart-rate classical conditioning.

Previous research on electrodermal conditioning suggests that the conditioned diminution of the unconditioned response (UR) has an associative basis. The aim of this experiment was to test whether this phenomenon also occurs in heart rate (HR) classical conditioning. For this purpose, a differential classical conditioning was performed. The conditioned stimuli (CSs) were geometrical shapes (the CS+ was a square and the CS- was a triangle) displayed on a computer screen and a burst of white noise was used as unconditioned stimulus (US). For analysis of the conditioned response (CR) components, an interval between CS+ and US of 8 seconds was used. After the acquisition phase, participants were tested using trials with the US preceded either by a CS+, a CS-, or a neutral stimulus (a circle). The results showed conditioned diminution of the UR and suggest that the second heart rate deceleration component (D2) is responsible for the occurrence of this phenomenon.

What is learned in patterning discriminations? Further tests of configural accounts of associative learning in human electrodermal conditioning

Two Pavlovian SCR conditioning experiments investigated positive and negative patterning discriminations in humans by means of transfer tests. In Experiment 1, positive patterning (A−, B−, AB+) was trained interleaved with non-reinforced presentations of an additional stimulus (C−). Then responding to new compounds consisting of either already trained elements (AC, BC) or new elements (DE) was examined. In Experiment 2, negative patterning (A+, B+, AB−) was trained interleaved with reinforced presentations of an additional stimulus (C+). Again, we examined responding to new compounds consisting of either already trained elements (AC, BC) or new elements (DE). In both experiments the initial patterning discrimination was solved successfully. The response patterns to the test compounds in both experiments were in contradiction to configural accounts of associative learning. In positive patterning human participants seemed to utilize ‘number’ or some other abstract feature in preference to available concrete stimuli. In negative patterning the abstract dimension of ‘separate-versus-together’ or ‘opposite’ was used.

Effects of conditioned stimulus presentation on diminution of the unconditioned response in aversive classical conditioning

The purpose of this experiment was to study whether conditioned diminution of the unconditioned response (UR) is a phenomenon with an associative basis. Discriminative electrodermal conditioning was used with an interval between the conditioned stimulus (CS) and unconditioned stimulus (US; aversive white-noise) of 8 s. Fifty-nine volunteer subjects received discrimination training in which one CS was reinforced (CS+/US) and a second CS was non-reinforced (CS−). After this discriminative training phase, participants were tested using intermixed trials in which a US was preceded by either a CS+, a CS−, or a neutral stimulus (NS). The results indicated that the skin conductance response amplitude of the UR was lower when the US was preceded by the CS+ than when the US was preceded by the CS− or the NS. However, NS/US presentations elicited URs of greater amplitude than those of the CS−/US presentations. The results can be explained in terms of orienting reflex reinstatement. In addition, it is argued that conditioned diminution has an associative basis.

Human blink startle during aversive and nonaversive Pavlovian conditioning.

Potentiation of blink startle during aversive and nonaversive Pavlovian single-cue conditioning was assessed in human Ss. In Experiment 1 (N = 89), the conditioning group received paired presentations of a visual conditioned stimulus (CS) and an unconditioned stimulus (US), whereas the control group was presented with a random sequence. The US was an electric shock for half the Ss and a nonaversive reaction time task for the other half. Electrodermal conditioning was evident regardless of the nature of the US, but blink potentiation was found only in the conditioning group that had been trained with the aversive US. These results were replicated in Experiment 2 (N = 65), in which a nonaversive US of increased motivational significance was used. Thus, only aversive conditioning seems to affect the affective valence of the CS, at least as reflected by changes in a skeletal reflex.

Latent inhibition in human Pavlovian differential conditioning: Effect of additional stimulation after preexposure and relation to schizotypal traits

Latent inhibition has been defined as the retardation of Pavlovian conditioning due to conditioned stimulus (CS) preexposure. The present study investigated (1) the effect of additional stimulation signalling the shift from preexposure to acquisition, and (2) the relationship between “schizotypal traits” and latent inhibition in human electrodermal conditioning. Three groups (48 subjects) were presented with 20 preexposure, 8 acquisition, and 8 extinction trials in a differential conditioning paradigm. One group received different stimuli during preexposure and acquisition, whereas the remaining groups (SAME, SAME + S) received the same stimuli throughout the experiment. In group SAME + S, an additional signal was presented at the end of the preexposure phase. Latent inhibition was evident in electrodermal first interval response conditioning during acquisition and second interval response conditioning during acquisition and extinction. Contrary to results from animal research, latent inhibition was not disrupted by the additional signal in group SAME + S. A covariation of schizotypal traits and latent inhibition was detected in both groups preexposed to the CSs. During acquisition, latent inhibition of electrodermal first interval response conditioning was evident in subjects scoring low in “schizotypy”, but not in high scorers. The latter results replicate previous findings obtained from a different latent inhibition paradigm.

Electrodermal Reactivity (EDR), Heart Rate (HR), personality and conditioning

Electrodermal Reactivity (EDR), Heart Rate (HR), personality and conditioning

Between- and within-subjects blocking in human electrodermal conditioning

Between- and within-subjects blocking in human electrodermal conditioning

The effects of false response feedback on human ‘Fear’ conditioning

This study describes a human electrodermal conditioning experiment in which subjects were given false skin conductance feedback during CS presentation. In comparison with appropriate attentional control groups, subjects who believed they were exhibiting a strong CR did actually emit a greater magnitude CR, while subjects who believed they were exhibiting only a weak CR emitted a significantly lower magnitude CR. When both self-report and behavioural measures of UCS revaluation were taken after conditioning, the evidence suggested that response feedback had not differentially affected subjects evaluation of the aversiveness of the UCS. The results suggest that the response modulating effects of response feedback observed in this and other studies are not caused by response feedback influencing evaluation of the UCS, but they are consistent with the hypothesis that beliefs about the nature of response feedback influence the strength of the UCS representation itself.

Brain asymmetry and human electrodermal conditioning

Two experiments are reviewed that demonstrate effects of brain laterality on human classical conditioning. Pictures of facial emotional expressions were used as conditioned stimuli (CSs) together with shock as unconditioned stimulus (UCS). Bilateral electrodermal responses were recorded as dependent measures. In the first experiment, one group was conditioned to an angry face, and one group to a happy face. During extinction, the face-CSs were presented to the right hemisphere on half of the trials and to the left hemisphere on the other half of the trials. Results showed that the right hemisphere was superior in showing persisting effects of learning, and especially to the angry CS+. In the second experiment, lateralized presentations of the angry and happy faces were made during acquisition, with foveal presentations during extinction. Once again, the angry face elicited greater skin conductance responses (SCRs) during extinction in the group that had this stimulus presented to the right hemisphere during acquisition. It is concluded that emotional conditioning is differentially regulated by the two hemispheres of the brain.

Effects of conditioned stimulus pre-exposure on human electrodermal conditioning to fear-relevant and fear-irrelevant stimuli

The effects of conditioned stimulus (CS) pre-exposure and fear-relevance of the CS on human Pavlovian electrodermal conditioning were investigated. A differential delayed conditioning paradigm was used with a CS-unconditioned stimulus (US; shock) interval of 8 s. In Experiment 1, 64 subjects were randomized into four groups, two of which received fear-relevant stimuli and the other two fear-irrelevant stimuli. Half of the subjects were pre-exposed to the to-be-CSs and the other half to two not-to-be-CSs, with 15 exposures of each stimulus. During acquisition, subjects received 8 reinforced and 8 nonreinforced CS+ and CS− trials, and during the extinction phase 15 nonreinforced trials of each CS. Pre-exposure to the to-be-CSs retarded conditioning for the first and second interval anticipatory responses (FIRs and SIRs); that is, a latent inhibition effect was demonstrated, although the results for the FIR were inconclusive. The expected effects of fear-relevance were not revealed. Experiment 2 addressed the question whether the long pre-exposure period interfered with the frequently observed “preparedness effect” of higher resistance to extinction to fear-relevant stimuli. The design was similar to that of Experiment 1, but for half of the subjects the acquisition phase was initiated immediately after a short rest period, and for the other half acquisition started after an extended rest period, equal to the duration of the pre-exposure phase in Experiment 1. Twenty extinction trials of each CS were presented. A reliable difference in arousal in terms of spontaneous fluctuations was produced by the rest periods, but although differential conditioning was observed, no effect of fear-relevance was seen during extinction.

The effects of cued UCS rehearsal on the retention of differential ‘fear’ conditioning: An experimental analogue of the ‘worry’ process

This study describes a human electrodermal conditioning experiment in which subjects were asked to mentally rehearse the UCS in a period following initial fear conditioning and prior to a test period involving nonreinforced presentations of the CS. Subjects who were asked to rehearse the UCS retained a differential fear CR during subsequent unreinforced presentations of the CS, but control subjects who were asked to rehearse either a nonaversive event or an aversive event unrelated to the UCS failed to retain the differential CR they had acquired during conditioning. These results suggest that rehearsal of the UCS during periods when CS and UCS are absent can aid the persistence of a fear CR in the absence of further pairings of the CS and UCS. It is argued that these effects can be explained in terms of the effect of UCS rehearsal on the strength and evaluation of the UCS representation. It is also suggested that cued UCS rehearsal might provide a useful procedure for understanding clinical incubation effects and for understanding how the ‘worry’ process contributes to the maintenance and incubation of fear.

Effects of conditioned stimulus fear-relevance and preexposure on expectancy and electrodermal measures of human Pavlovian conditioning.

The present research investigated the effects of fear-relevance of the conditioned stimulus (CS) and CS preexposure on human electrodermal conditioning and on a continuous measure of expectancy of the unconditioned stimulus (US). Both experiments employed 20 preexposure, 8 acquisition, and 8 extinction trials in a differential Pavlovian conditioning paradigm with shock as the US. In Experiment 1 (N = 48), electrodermal conditioning was retarded by CS preexposure, but was not influenced by fear-relevance of the CS. Expectancy of the US was retarded by preexposure only in the fear-relevant condition. In Experiment 2 (N = 48), the CS/US contingencies was embedded in a visual masking task. Preexposure retarded both electrodermal conditioning and US expectancy. Neither measure was influenced by fear-relevance of the CS. However, fewer subjects in the preexposure condition learned the CS/US relationship and those who did, did so on later trial than those in the no-preexposure condition. Thus, the results indicated clear retardation of conditioning as a result of preexposure, but no reliable effect of fear-relevance.