Return of fear in a human differential conditioning paradigm caused by a return to the original acquistion context

In a differential human fear conditioning paradigm evidence for ABA-renewal was obtained manipulating the lighting in the experimental room. During acquisition in either a dark or illuminated room, one neutral slide was sometimes paired with a loud aversive noise whereas another slide was not. Subsequently, extinction took place in the opposite lighting context. When afterwards the participants were tested again in the original acquisition context, measurements revealed a recovery of the conditioned electrodermal response and an increase in the retrospective verbal US-expectancy ratings. No response recovery was obtained in an AAA-group that received acquisition, extinction and test trials in one and the same context. Several theoretical explanations for this type of return of fear as well as implications for clinical practice are discussed.     

Return of fear after retrospective inferences about the absence of an unconditioned stimulus during extinction

We examined whether the effect of an extinction phase can be influenced retrospectively by information about the cause of the absence of the unconditioned stimulus (US) during that phase. Participants were subjected to a differential fear conditioning procedure, followed by an extinction procedure. Afterwards, half of the participants were presented with information about a technical failure, which explained why the US had been absent during the extinction phase. The other participants received information that was unrelated to the US. During a subsequent presentation of the target conditioned stimulus (CS), only the former group of participants showed renewed anticipatory skin conductance responding and a return of US expectancy. The results are in accordance with a propositional account of associative learning and highlight the importance of retrospective reasoning as a cause of relapse after exposure therapy.     

All we need is a cue to remember: the effect of an extinction cue on renewal

In the present study, it was investigated by employing a human fear conditioning paradigm whether an extinction retrieval cue can attenuate renewal of conditioned responding after an extinction treatment procedure, and if so, what the precise role of such an extinction cue comprises. It was hypothesized that such a cue can attenuate renewal and would function as a safety signal capable of directly inhibiting the expectancy of an aversive outcome and conditioned skin conductance responding to a conditioned stimulus. The results demonstrated that the extinguished expectancy of an aversive outcome was renewed when the CS was presented outside the extinction context and that an extinction cue attenuated this effect. This extinction cue, however, only transferred its inhibitory properties to other, non-extinguished stimuli when there was no contextual switch. This safety signal function was not observed after a switch in context. Possible functions of the extinction cue and its application in extinction-based exposure treatments are discussed.     

疼痛恐惧的形成、泛化与消退

疼痛恐惧源于把疼痛等同于伤害的灾难化信念及对疼痛的负性解释, 它在慢性疼痛和能力丧失的发生和发展过程中起着重要作用。疼痛恐惧可以通过联合学习和观察学习等方式获得, 并且在具有相似特征的刺激中存在泛化现象。通过教育干预和等级暴露疗法等可以成功消退疼痛恐惧, 在消退过程中要控制安全信息等因素的不良影响。在疼痛恐惧的获得与消退中, 主要有杏仁核, 脑岛和前扣带皮层等脑区参与。未来的研究可以集中在深入探讨疼痛恐惧形成中的泛化及消退后的恢复、再巩固等现象, 加强其临床上的应用, 并综合心理、生物和认知神经科学, 研究疼痛恐惧的获得、泛化与消退的深层机制。     

Reinstatement of fear responses in human aversive conditioning

The treatment of choice for a number of anxiety disorders is exposure therapy. However, successful reduction of fear through exposure is sometimes followed by a (partial) return of symptoms of fear (return of fear, ROF; Clin. Psychol. Rev. 9 (1989) 147). Several possible learning mechanisms have been suggested to explain ROF (e.g. mechanisms related to spontaneous recovery, renewal, reacquisition and reinstatement). The present study focuses on reinstatement, which refers to the observation that mere US-only presentations can 'reinstate' previously extinguished fear responses. Although animal research has repeatedly demonstrated this phenomenon, little is known about fear reinstatement in humans. The present study employed a differential aversive conditioning procedure: after acquisition and a subsequent extinction procedure, a series of four unpredicted US-only trials was scheduled in the reinstatement group. The control group did not receive additional US presentations. A significant reinstatement effect was observed for US-expectancy ratings and fear ratings in the reinstatement group, but not in the control group. No differences were observed in a reaction time measure of resource allocation to the conditioned stimuli. These findings constitute a first demonstration of reinstatement of conditioned fear responses in humans. Implications for exposure treatment and suggestions for future research are discussed.     

Contextual control of human fear associations in a renewal paradigm

The original model of behavior change suggests that extinction is context dependent whereas fear acquisition is context independent [Bouton, M. E. & Ricker, S. T. (1994). Renewal of extinguished responding in a second context. Animal Learning and Behavior, 22, 317-324]. Supportive evidence stems mainly from animal studies, showing that after acquisition (conditioned stimulus-unconditioned stimulus (CS-US)) in Context A and extinction in Context B, fear is renewed by presenting the CS in acquisition Context A (ABA renewal) or in a novel Context C (ABC renewal). By implication, the model predicts equal ABA and ABC renewal. However, there is also evidence to suggest that the context dependency of extinction and the context independency of acquisition may be less stringent than originally proposed. The present study investigated renewal in humans using a differential fear conditioning paradigm with a shock US and online shock expectancy ratings and electrodermal responses as dependent variables. Experiment 1 compared an ABA condition with an AAA condition. Experiment 2 compared three conditions: ABA, ABC, and AAA. Both experiments demonstrated ABA renewal. Most importantly, Experiment 2 showed larger ABA than ABC renewal. Overall, results for expectancy ratings were more convincing than for electrodermal responses. In line with the extinction model, the present findings support the context dependency of extinction in humans. In contrast to the model, the findings suggest that in humans not only extinction learning, but also fear acquisition is controlled by its current context.     

Extensive extinction in multiple contexts eliminates the renewal of conditioned fear in rats

Two studies examined whether nonreinforcement of a stimulus in multiple contexts, instead of a single context, would decrease renewal of conditioned fear in rats (as assessed by conditioned suppression of lever pressing). In Experiment 1, renewal was measured after 36 nonreinforced CS trials delivered during six extinction sessions in a single context or two extinction sessions in each of three different contexts. The number of extinction contexts did not have an effect on renewal. In Experiment 2, groups received either 36 or 144 nonreinforced CS trials during six or twenty-four extinction sessions in a single context or three different contexts. Again, renewal was not influenced by the number of extinction contexts when only 36 trials were given. However, when 144 trials were used, renewal was completely eliminated when extinction was divided between 3 contexts, but was not weakened when the sessions took place in a single context. The results suggest that the use of multiple treatment settings in exposure-based therapies is only likely to reduce relapse if a sufficient number of sessions are provided in each of the treatment settings.     

Concurrent excitors limit the extinction of conditioned fear in humans

In a human fear conditioning experiment, with on-line expectancy ratings and electrodermal responding as indices of fear, two neutral stimuli (pictures of geometric shapes) were first established as reliable predictors of an electric shock. In the subsequent extinction phase, the two stimuli were repeatedly presented in compound, without the shock. The final test phase consisted of individual stimulus presentations again, which resulted in a strong return of the conditioned responses. This effect was not observed in non-conditioned control stimuli. Hence, behavioral effects of extinction seem highly specific to the stimulus constellation that has gone through the extinction procedure. We argue that pharmacological, behavioral and/or cognitive manipulations that could prevent configural processing of stimulus constellations have direct clinical potential.     

Pentylenetetrazole as an unconditioned stimulus for olfactory and contextual fear conditioning in rats

The association of five footshocks with a neutral odor is able to establish an olfactory fear conditioning in rats. The present study sought to investigate whether the systemic administration of pentylenetetrazole (PTZ; 3.75–15 mg/kg) would turn the coffee odor in a conditioned stimulus in the fear conditioning paradigm. The results showed that rats started to display risk assessment and avoidance after PTZ (15 mg/kg)–coffee odor pairing. When three mild footshocks (0.4 mA for 2 s) were delivered during this pairing, the conditioned response exhibited was greater than before. In both cases, however, pretreatment with the benzodiazepine midazolam (MDZ. 0.5 mg/kg i.p.) fully counteracted the expression of these defensive behaviors. Moreover, after being paired with 15 mg/kg of PTZ alone or combined with footshocks, the coffee odor was able to promote a new fear conditioning related to the context where it was re-exposed. The present findings point out the usefulness of PTZ as an unconditioned stimulus to promote fear conditioning to olfactory and contextual cues in rats.     

Return of experimentally induced chocolate craving after extinction in a different context: divergence between craving for and expecting to eat chocolate

Unlike in fear conditioning, little attention has been devoted to extinction and renewal in appetitive conditioning, despite its relevance for extinction-based addiction treatments. We developed a paradigm, using a specific tray as a conditioned stimulus (CS) for eating chocolate (unconditioned stimulus, US), to investigate the effects of context change on acquisition and extinction of conditioned chocolate craving using an ABA renewal design. In Study 1 (n=32), participants successfully acquired chocolate craving, but unlike what is commonly observed in fear conditioning, craving did not extinguish. In Study 2, we separately assessed craving and US expectancy in a between-subjects design (n=64). US-expectancy data showed acquisition, extinction and renewal in the ABA group. The craving data did not follow this pattern, suggesting different mechanisms for craving and US expectancy. Similarities and differences between craving and US expectancy, as well as practical implications, are discussed.     

Use of the ABA fear renewal paradigm to assess the effects of extinction with co-present fear inhibitors or excitors: Implications for theories of extinction and for treating human fears and phobias

In four experiments using albino rats in an ABA fear renewal paradigm, we studied conditioned fear in the A test context following extinction in Context B. Conditioned suppression of operant responding was the index of fear. In Experiments 1-3, we found that extinguishing a feared cue in compound with a putative conditioned inhibitor of fear led to more fear in the test context than did a conventional extinction procedure. In Experiments 4a and 4b, we found that extinguishing three feared cues in compound required one third the time and generally led to less fear to the cues in the test context than did the extinction of each cue separately. Thus, fear in the test context seems to vary inversely with the values of co-present cues during extinction in Context B. Results imply that cue value is actually reduced by extinction procedures rather than merely being opposed by a growing inhibitory process. Implications for theories of renewal and for clinical practice are discussed.     

Associations in human instrumental conditioning

Four experiments were conducted to study the contents of human instrumental conditioning. Experiment 1 found positive transfer between a discriminative stimulus (S^D) and an instrumental response (R) that shared the outcome (O) with the response that was originally trained with the S^D, showing the formation of an S^D → O association. Experiment 2 found that post-acquisition devaluation of an outcome selectively reduced the response trained with that outcome, showing the formation of a R → O association. In Experiment 3, changing the outcome did not prevent participants from giving the response learned with each S^D, even though none of the responses was appropriate for the new outcome, showing evidence of the formation of S^D → R associations in instrumental learning. The three binary associations were shown within the same basic experimental situation. Finally, Experiment 4 found evidence of the formation of the higher order association S^D(R → O) in human instrumental conditioning.     

Effects of multiple contexts and context similarity on the renewal of extinguished conditioned behaviour in an ABA design with humans

The ABA renewal procedure involves pairing a conditional stimulus (CS) and an unconditional stimulus (US) in one context (A), presenting extinction trials of the CS alone in a second context (B), and nonreinforced test trials of the CS in the acquisition context (A). The renewal of extinguished conditioned behaviour is observed during test. The current study tested the effects of multiple extinction contexts and context similarity in attenuating renewal. Participants (N = 99) took part in a fear conditioning ABA renewal procedure. Using a measure of self-reported expectancy of the US, ABA renewal was observed when a single extinction context that was dissimilar to the test context was used. Renewal was attenuated, though still present, when extinction occurred in multiple dissimilar extinction contexts or in a single extinction context that was similar to the test context. Renewal was completely abolished when multiple extinction contexts that were similar to the test context were combined. Multiple extinction contexts and context similarity act additively in their effect on attenuating renewal. The results are discussed in relation to the design of exposure therapy programs that seek to reduce relapse that can occur via renewal.