Overcoming avoidance in anxiety disorders: The contributions of Pavlovian and operant avoidance extinction methods

Unconditioned stimulus devaluation decreases the generalization of costly safety behaviors

Safety behaviors are often maladaptive in clinical anxiety as they typically persist without realistic threat and cause various impairments. In the laboratory, safety behaviors are modelled by responses to a conditioned stimulus (CS) that reduce the occurrence of an expected aversive unconditioned stimulus (US). Preliminary evidence suggests that US devaluation, a procedure that decreases US aversiveness, devalues the threat value of the CS and thus diminishes safety behaviors to the CS. This study (n = 78) aimed to extend this finding and examined whether US-devaluation can reduce the generalization of safety behaviors to various stimuli. After acquiring safety behaviors to CSs of different categories, the US predicted by one CS category was devalued. In test, participants showed a selective reduction in safety behaviors to novel stimuli of the devalued CS category, reflecting a decrease in generalization of safety behaviors. Trait anxiety was associated with persistent generalized safety behaviors to novel stimuli of the devalued category. We discuss how US devaluation may improve treatment outcome but also the challenges of clinical translation.

Fear in action: Fear conditioning and alleviation through body movements

Fear memories enhance survival especially when the memories guide defensive movements to minimize harm. Accordingly, fear memories and body movements have tight relationships in animals: Fear memory acquisition results in adapting reactive defense movements, while training active defense movements reduces fear memory. However, evidence in humans is scarce because their movements are typically suppressed in experiments. Here, we tracked adult participants' body motions while they underwent ecologically valid fear conditioning in a 3D virtual space. First, with body motion tracking, we revealed that distinct spatiotemporal body movement patterns emerge through fear conditioning. Second, subsequent training to actively avoid threats with naturalistic defensive actions led to a long-term (24 h) reduction of physiological and embodied conditioned responses, while extinction or vicarious training only transiently reduced the responses. Together, our results highlight the role of body movements in human fear memory and its intervention.

Tackling Costly Fearful Avoidance Using Pavlovian Counterconditioning

Avoidance behavior constitutes a major transdiagnostic symptom that exacerbates anxiety. It hampers fear extinction and predicts poor therapy-outcome. Pavlovian counterconditioning with a reward could alleviate avoidance better than traditional extinction by reducing negative valence of the feared situation. However, previous studies are scarce and did not consider that pathological avoidance is often costly and typically evolves from an approach-avoidance conflict. Therefore, we used an approach-avoidance conflict paradigm to model effects of counterconditioning on costly avoidance (i.e., avoidance that leads to missing out on rewards). Results from our preregistered Bayesian Mixed Model analyses in 51 healthy participants (43 females) indicated that counterconditioning was more effective in reducing negative valuation and decreasing costly avoidance than traditional extinction. This study supports application of a simple counterconditioning technique, shows that its efficacy transfers to more complex avoidance situations, and suggests treatment may benefit from increasing reward drive in combination with extinction to overcome avoidance. Application in a clinical sample is a necessary next step to assess clinical utility of counterconditioning.

Latent-state and model-based learning in PTSD

Post-traumatic stress disorder (PTSD) is characterized by altered emotional and behavioral responding following a traumatic event. In this article, we review the concepts of latent-state and model-based learning (i.e., learning and inferring abstract task representations) and discuss their relevance for clinical and neuroscience models of PTSD. Recent data demonstrate evidence for brain and behavioral biases in these learning processes in PTSD. These new data potentially recast excessive fear towards trauma cues as a problem in learning and updating abstract task representations, as opposed to traditional conceptualizations focused on stimulus-specific learning. Biases in latent-state and model-based learning may also be a common mechanism targeted in common therapies for PTSD. We highlight key knowledge gaps that need to be addressed to further elaborate how latent-state learning and its associated neurocircuitry mechanisms function in PTSD and how to optimize treatments to target these processes.

Working hard to avoid: Fixed-ratio response effort and maladaptive avoidance in humans

Maladaptive avoidance of safe stimuli is a defining feature of anxiety and related disorders. Avoidance may involve physical effort or the completion of a fixed series of responses to prevent occurrence of, or cues associated with, the aversive event. Understanding the role of response effort in the acquisition and extinction of avoidance may facilitate the development of new clinical treatments for maladaptive avoidance. Despite this, little is known about the impact of response effort on extinction-resistant avoidance in humans. Here, we describe findings from two laboratory-based treatment studies designed to investigate the impact of high and low response effort on the extinction (Experiment 1) and return (Experiment 2) of avoidance. Response effort was operationalised as completion of fixed-ratio (FR) reinforcement schedules for both danger and safety cues in a multi-cue avoidance paradigm with behavioural, self-report, and physiology measures. Completion of the FR response requirements cancelled upcoming shock presentations following danger cues and had no impact on the consequences that followed safety cues. Both experiments found persistence of high response-effort avoidance across danger and safety cues and sustained (Experiment 1) and reinstated (Experiment 2) levels of fear and threat expectancy. Skin conductance responses evoked by all cues were similar across experiments. The present findings and paradigm have implications for translational research on maladaptive anxious coping and treatment development.

Online counterconditioning with COVID-19-relevant stimuli in lockdown: Impact on threat expectancy, fear, and persistent avoidance

BACKGROUND AND OBJECTIVES

In counterconditioning, a conditioned aversive stimulus (CS) is paired with an appetitive stimulus to reduce fear and avoidance. Findings are, however, mixed on the relative impact of counterconditioning versus standard extinction, where the CS is presented in the absence of the aversive event. This analogue treatment study investigated the impact of counterconditioning relative to standard extinction on threat expectancy, fear, and persistent avoidance with an online fear-conditioning task conducted with COVID-19-relevant appetitive stimuli during the pandemic.

METHODS

Following habituation, in which two CSs (male faces wearing face-coverings) were presented in the absence of the unconditioned stimulus (US; a loud female scream), participants (n = 123) underwent threat-conditioning where one stimulus (CS+) was followed by the US and another (CS-) was not. In avoidance learning, the US could be prevented by making a simple response in the presence of the CS+. Next, participants received either counterconditioning in which trial-unique positively rated images of scenes from before the COVID-19 pandemic and its associated restrictions (e.g., hugging others and holding hands) were presented with the CS + or no-counterconditioning (i.e., extinction). In the final test phase, avoidance was available, and all US deliveries were withheld.

RESULTS

Counterconditioning led to diminished threat expectancy and reduced avoidance relative to no-counterconditioning. Fear ratings did not differ between groups.

LIMITATIONS

No physiological measures were obtained.

CONCLUSIONS

Implemented online during the pandemic with COVID-19-relevant appetitive stimuli, counterconditioning was effective at reducing persistent avoidance and threat expectancy.

Blockade of Ghrelin Receptor Signaling Enhances Conditioned Passive Avoidance and Context-Associated cFos Activation in Fasted Male Rats

INTRODUCTION

Interoceptive feedback to the brain regarding the body's physiological state plays an important role in guiding motivated behaviors. For example, a state of negative energy balance tends to increase exploratory/food-seeking behaviors while reducing avoidance behaviors. We recently reported that overnight food deprivation reduces conditioned passive avoidance behavior in male (but not female) rats. Since fasting increases circulating levels of ghrelin, we hypothesized that ghrelin signaling contributes to the ability of fasting to reduce conditioned avoidance.

METHODS

Ad libitum-fed male rats were trained in a passive avoidance procedure using mild footshock. Later, following overnight food deprivation, the same rats were pretreated with ghrelin receptor antagonist (GRA) or saline vehicle 30 min before avoidance testing.

RESULTS

GRA restored passive avoidance in fasted rats as measured by both latency to enter and time spent in the shock-paired context. In addition, compared to vehicle-injected fasted rats, fasted rats that received GRA before reexposure to the shock-paired context displayed more cFos activation of prolactin-releasing peptide (PrRP)-positive noradrenergic (NA) neurons in the caudal nucleus of the solitary tract, accompanied by more cFos activation in downstream target sites of PrRP neurons (i.e., bed nucleus of the stria terminalis and paraventricular nucleus of the hypothalamus).

DISCUSSION

These results support the view that ghrelin signaling contributes to the inhibitory effect of fasting on learned passive avoidance behavior, perhaps by suppressing recruitment of PrRP-positive NA neurons and their downstream hypothalamic and limbic forebrain targets.

Understanding relations between intolerance of uncertainty and body checking and body avoiding in anorexia nervosa

BACKGROUND

A key feature of anorexia nervosa is body image disturbances and is often expressed by dysfunctional body-related behaviours such as body checking and body avoiding. These behaviours are thought to contribute to both the maintenance and relapse of AN, yet empirical evidence is scarce. One variable that may contribute to the need for engaging in these behaviours is intolerance of uncertainty. This study aims to investigate body checking and body avoiding and its relations with intolerance of uncertainty in women with anorexia nervosa (AN-ill; 70), women recovered from AN (AN-rec; 85) and control group (127).

METHODS

Three questionnaires were completed, measuring eating pathology, intolerance of uncertainty and body checking and body avoiding. One-way ANOVAS were used to test group differences. Moderation analyses were used to investigate associations between variables.

RESULTS

Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill followed by AN-rec and, lastly, the control group, confirming group differences. Intolerance of uncertainty was associated with body checking in the AN-rec group and the control group but not in the AN-ill group. The association between intolerance of uncertainty and body avoiding was reported in the AN-rec group and only marginally in the control group.

CONCLUSION

Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill, however still elevated in AN-rec, confirming the presence of body image disturbances, even after recovery. The unique associations between intolerance of uncertainty and body checking and body avoiding within the studied groups may represent different stages of the illness. In the AN-rec group, the relation between intolerance of uncertainty, body checking and body avoiding may be driven by trait anxiety. For AN-ill group, body checking and body avoiding may eventually have grown into habitual patterns, rather than a strategy to ameliorate anxiety and uncertainty. Women with anorexia nervosa often experience disturbances in their body image and are expressed in body-related behaviours such as body checking and body avoiding. These behaviours are thought to contribute to both the maintenance and relapse of anorexia nervosa. Intolerance of uncertainty is defined as the incapacity to tolerate uncertainty and may contribute to the need for engaging in these behaviours. This study aims to investigate body checking and body avoiding and its relations with intolerance of uncertainty in women with anorexia nervosa (AN-ill; 70), women recovered from AN (AN-rec; 85) and control group (127). Three questionnaires were completed, measuring eating pathology, intolerance of uncertainty and body checking and body avoiding. Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill and still elevated in AN-rec, even after recovery. The associations between intolerance of uncertainty and body checking and body avoiding within the studied groups may represent different stages of the illness. In the AN-rec group, the relation between intolerance of uncertainty, body checking and body avoiding may be driven by trait anxiety. For AN-ill group, body checking and body avoiding may have grown into habitual patterns, rather than a strategy to ameliorate anxiety and uncertainty.

The role of relief, perceived control, and prospective intolerance of uncertainty in excessive avoidance in uncertain-threat environments

Excessive avoidance is a key feature of pathological anxiety. However, the precise mechanisms underlying the development of excessive avoidance are still unknown. In the present study, we tested the hypothesis that excessive avoidance, especially in individuals with high Intolerance of Uncertainty (IU) is aimed at distress reduction via the enhancement of subjective perceived control in uncertain-threat environments. In our experiment, participants learned to avoid an uncertain aversive sound through a discriminated free operant procedure. In a later test phase in extinction, we manipulated the amount of avoidance responses available per trial by creating a limited and an unrestricted response condition. Nonetheless, the aversive sound could be effectively avoided in both conditions. We measured response frequency, avoidance confidence ratings and anxiety-predisposing traits such as intolerance of uncertainty, trait anxiety and distress tolerance. The degree of distress suffered during trials was inferred from post-trial relief ratings that were requested after trials in which the aversive sound had been omitted. In the avoidance acquisition phase, we found a positive association between prospective intolerance of uncertainty (P-IU) and the decline rate of distress. This relationship was not significant, however, when inhibitory intolerance of uncertainty (I-IU) was controlled for. At test, we found that the increase in avoidance responses led to distress reduction through the enhancement of avoidance confidence. Finally, we found a significant modulating role of P-IU in the effect of response limit on distress reduction that lends further support to our hypothesis. Specifically, P-IU was positively associated with the effect of response limit on distress. However, such modulating role was not significant when controlling for trait anxiety or I-IU.

No sound is more distracting than the one you're trying not to hear: delayed costs of mental control of task-irrelevant neutral and emotional sounds

Background

Suppressing intrusive thoughts can result in a post-suppression rebound effect where the same thoughts become hyperaccessible. The current study aimed to investigate if similar so-called rebound effects could be observed when people attempted to mentally suppress awareness of nonsensical auditory stimuli. Based on previous research on thought suppression and mental control in other domains, we hypothesized that attempting to suppress awareness of a task-irrelevant sound while under cognitive load would impact evaluations of the sound on affective dimensions and loudness, and result in increased general vigilance, as evidenced by faster responding on subsequent tasks.

Methods

We performed two experiments where participants in a suppression condition were initially instructed to mentally suppress awareness of a sound while performing a mentally challenging task. Participants in a control condition performed the same task without receiving any instructions regarding the sound. In Experiment 1, the sound was affectively neutral, while in Experiment 2 participants were presented with an inherently aversive (tinnitus-like) sound. After this initial phase, participants performed tasks measuring vigilance and attention, and were also asked to give subjective ratings of the sounds on a number of affective dimensions and loudness.

Results

In Experiment 1, participants in the suppression condition showed faster response times on both a visual search task and an auditory spatial cueing task, as compared to participants in the control condition. Contrary to our predictions, participants in the suppression condition did not rate the distractor sound as louder than participants in the control condition, and there were no differences on affective dimensions. In Experiment 2, results revealed that participants in the suppression condition made more errors on a visual search task, specifically on trials where the previously suppressed sound was presented. In contrast to results from Experiment 1, participants in the suppression condition also rated the targeted sound as louder.

Conclusions

The findings provide preliminary support for a post-suppression rebound effect in the auditory domain and further suggest that this effect may be moderated by the emotional properties of the auditory stimulus.

The Good, the Bad, and the Ugly-Chances, Challenges, and Clinical Implications of Avoidance Research in Psychosomatic Medicine

Avoidance behaviors are shaped by associative learning processes in response to fear of impending threats, particularly physical harm. As part of a defensive repertoire, avoidance is highly adaptive in case of acute danger, serving a potent protective function. However, persistent or excessive fear and maladaptive avoidance are considered key factors in the etiology and pathophysiology of anxiety- and stress-related psychosomatic disorders. In these overlapping conditions, avoidance can increase the risk of mental comorbidities and interfere with the efficacy of cognitive behavioral treatment approaches built on fear extinction. Despite resurging interest in avoidance research also in the context of psychosomatic medicine, especially in conditions associated with pain, disturbed interoception, and disorders of the gut-brain axis, current study designs and their translation into the clinical context face significant challenges limiting both, the investigation of mechanisms involved in avoidance and the development of novel targeted treatment options. We herein selectively review the conceptual framework of learning and memory processes, emphasizing how classical and operant conditioning, fear extinction, and return of fear shape avoidance behaviors. We further discuss pathological avoidance and safety behaviors as hallmark features in psychosomatic diseases, with a focus on anxiety- and stress-related disorders. Aiming to emphasize chances of improved translational knowledge across clinical conditions, we further point out limitations in current experimental avoidance research. Based on these considerations, we propose means to improve existing avoidance paradigms to broaden our understanding of underlying mechanisms, moderators and mediators of avoidance, and to inspire tailored treatments for patients suffering from psychosomatic disorders.

The effect of social anxiety on the acquisition and extinction of low-cost avoidance

Excessive avoidance and safety behaviours are a hallmark feature of social anxiety disorder. However, the conditioning and extinction of avoidance behaviour in social anxiety is understudied. Here, we examined the effect of individual differences in social anxiety on low-cost operant avoidance conditioning and extinction in 80 female participants. We employed an avoidance conditioning and extinction paradigm and measured skin conductance response, threat expectancy ratings and avoidance behaviour throughout the task. Findings demonstrated that elevated levels of social anxiety predicted the generalisation of conditioned avoidance responses across to safety cues during avoidance conditioning. When the opportunity to avoid was returned after the threat extinction phase, elevated social anxiety was associated with increased avoidance behaviour to threat cues. The results suggest that compromised extinction of avoidance behaviour is a characteristic of social anxiety and supports the strategy of minimising avoidance and safety behaviours during exposure therapy for the treatment of social anxiety disorder. Future research should utilise the avoidance conditioning and extinction paradigm as a laboratory model for clinical research to investigate how, and under what circumstances, the extinction of avoidance and safety behaviours can be improved for individuals high in social anxiety.

Sex and metabolic state interact to influence expression of passive avoidance memory in rats: Potential contribution of A2 noradrenergic neurons

Competing motivational drives coordinate behaviors essential for survival. For example, interoceptive feedback from the body during a state of negative energy balance serves to suppress anxiety-like behaviors and promote exploratory behaviors in rats. Results from past research suggest that this shift in motivated behavior is linked to reduced activation of specific neural populations within the caudal nucleus of the solitary tract (cNTS). However, the potential impact of metabolic state and the potential role of cNTS neurons on conditioned avoidance behaviors has not been examined. The present study investigated these questions in male and female rats, using a task in which rats learn to avoid a context (i.e., a darkened chamber) after it is paired with a single mild footshock. When rats later were tested for passive avoidance of the shock-paired chamber, male rats tested in an overnight food-deprived state and female rats (regardless of feeding status) displayed significantly less avoidance compared to male rats that were fed ad libitum prior to testing. Based on prior evidence that prolactin-releasing peptide (PrRP)-positive noradrenergic neurons and glucagon-like peptide 1 (GLP1)-positive neurons within the cNTS are particularly sensitive to metabolic state, we examined whether these neural populations are activated in conditioned rats after re-exposure to the shock-paired chamber, and whether neural activation is modulated by metabolic state. Compared to the control condition, chamber re-exposure activated PrRP+ noradrenergic neurons and also activated neurons within the anterior ventrolateral bed nucleus of the stria terminalis (vlBNST), which receives dense input from PrRP+ terminals, in both male and female rats when fed ad libitum. In parallel with sex differences in passive avoidance behavior, PrRP+ neurons were less activated in female vs. male rats after chamber exposure. GLP1+ neurons were not activated in either sex. In both sexes, overnight food deprivation before chamber re-exposure reduced activation of PrRP+ neurons, and also reduced vlBNST activation. Our results support the view that PrRP+ noradrenergic neurons and their inputs to the vlBNST contribute to the expression of passive avoidance memory, and that this contribution is modulated by metabolic state.

The role of intolerance of uncertainty in classical threat conditioning: Recent developments and directions for future research

Intolerance of uncertainty (IU), the tendency to find uncertainty aversive, is an important transdiagnostic dimension in mental health disorders. Over the last decade, there has been a surge of research on the role of IU in classical threat conditioning procedures, which serve as analogues to the development, treatment, and relapse of anxiety, obsessive-compulsive, and trauma- and stressor-related disorders. This review provides an overview of the existing literature on IU in classical threat conditioning procedures. The review integrates findings based on the shared or discrete parameters of uncertainty embedded within classical threat conditioning procedures. Under periods of unexpected uncertainty, where threat and safety contingencies change, high IU, over other self-reported measures of anxiety, is specifically associated with poorer threat extinction learning and retention, as well as overgeneralisation. Under periods of estimation and expected uncertainty, where the parameters of uncertainty are being learned or have been learned, such as threat acquisition training and avoidance learning, the findings are mixed for IU. These findings provide evidence that individual differences in IU play a significant role in maintaining learned fear and anxiety, particularly under volatile environments. Recommendations for future research are outlined, with discussion focusing on how parameters of uncertainty can be better defined to capture how IU is involved in the maintenance of learned fear and anxiety. Such work will be crucial for understanding the role of IU in neurobiological models of uncertainty-based maintenance of fear and anxiety and inform translational work aiming to improve the diagnosis and treatment of relevant psychopathology.

Optimizing Long-term Outcomes of Exposure for Chronic Primary Pain from the Lens of Learning Theory

Exposure in vivo is a theory-driven and widely used treatment to tackle functional disability in people with chronic primary pain. Exposure is quite effective; yet, in line with exposure outcomes for anxiety disorders, a number of patients may not profit from it, or relapse. In this focus article, we critically reflect on the current exposure protocols in chronic primary pain, and provide recommendations on how to optimize them. We propose several adaptations that are expected to strengthen inhibitory learning and/or retrieval of the extinction memory, thus likely decreasing relapse. We summarize the limited, but emerging experimental data in the pain domain, and draw parallels with experimental evidence in the anxiety literature. Our reflections and suggestions pertain to the use of the fear hierarchy, reassurance, positive psychology interventions, exposure with a range of stimuli and within different contexts, and the use of safety behaviors during treatment, as well as associating the fear-inducing stimuli with novel outcomes. In addition, we reflect on the importance of specifically tackling (the return of) pain-related avoidance behavior with techniques such as disentangling fear from avoidance and reinforcing approach behaviors. Finally, we discuss challenges in the clinical application of exposure to improve functioning in chronic primary pain and possible avenues for future research. Perspectives: Inspired by recent advances in learning theory and its applications on the treatment of anxiety disorders, we reflect on the delivery of exposure treatment for chronic primary pain and propose strategies to improve its long-term outcomes.

Explorations of avoidance and approach coping and perceived stress with a computer-based avatar task: detrimental effects of resignation and withdrawal

Background

Individuals differ in how they react to stress or trauma through different coping styles in which they may deal directly with a stressor by adopting approach coping styles or disengage with a stressor by utilizing avoidant coping styles. Avoidant coping styles have been linked to adverse outcomes including psychological distress, anxiety disorders, and post-traumatic stress disorder (PTSD). Recently, avoidance coping styles as measured by a subset of items on the Brief COPE were found to have a weak positive relationship with performance on a computer-based avatar task which is related to avoidant personality temperaments. This avatar task was developed as an alternative for paper and pencil self-report inventories for measuring avoidant tendencies based on possible response biases of avoidant individuals. In the current study, avoidance and approach coping styles as measured by the Brief Approach/Avoidance Coping Questionnaire (BACQ) were compared to avoidant coping as measured by the Brief COPE and performance on the avatar task. In addition to approach and avoidance coping, the BACQ also measures active avoidance coping (i.e., diversion) and passive avoidance coping (i.e., resignation and withdrawal). The relationships between approach and avoidance coping and performance on the avatar task were also analyzed with the outcome of perceived stress as measured by the Perceived Stress Scale (PSS).

Methods

One hundred undergraduates voluntarily completed the BACQ, the Brief COPE, and the PSS. Participants also completed a computer-based task in which they guided an avatar through a series of social situations where they indicated how they would interact with or avoid interacting with strangers.

Results

Approach coping had a weak negative relationship to avoidance coping as measured by the BACQ and the Brief COPE. Performance on the avatar task had a moderate positive relationship with avoidance coping (diversion as well as resignation and withdrawal) as measured by the BACQ and a moderate negative relationship with approach coping as measured by the BACQ. A model including only approach, diversion, and resignation and withdrawal coping best predicted performance on the avatar task in a linear regression model. While resignation and withdrawal coping and diversion coping had moderate positive relationships to avatar task scores, only resignation and withdrawal had a strong positive relationship to perceived stress. A model than included only resignation and withdrawal coping best predicted perceived stress in a linear regression model. Overall, passive avoidant coping styles (i.e., resignation and withdrawal), but not active avoidant coping style (i.e., diversion), were related to perceived stress. These results support the continued study of multiple aspects of avoidant coping styles as well as the avatar task to increase our understanding of the maladaptive effects of excessive avoidance in the face of stress.

Incentive-based, instructed, and social observational extinction of avoidance: Fear-opposite actions and their influence on fear extinction

Avoidance is a transdiagnostic symptom of clinical anxiety and its reduction a major focus of cognitive-behavioral treatments. This study examined the instrumental extinction of goal-directed avoidance by means of incentives, verbal instruction, and social observation and their influence on fear extinction. Participants acquired conditioned fear and instrumental avoidance responses (N = 160). In four randomized groups, the reduction of avoidance by incentives for non-avoidance, instructions to refrain from avoidance, and social observation of non-avoidance was compared to no intervention before removing the aversive outcome. Conditioned fear when avoidance became unavailable subsequently was tested. Incentives, instruction, and observation all reduced avoidance better than no intervention, however, with different degrees and influence on conditioned fear. Incentives and instructions strongly reduced avoidance despite high levels of fear (i.e., fear-opposite actions). This initiated fear extinction, thereby reducing conditioned fear when avoidance became unavailable. Social observation directly reduced conditioned fear, presumably because it conveyed additional information about the absence of the aversive outcome. However, observation only moderately reduced avoidance and resulted in higher fear when avoidance became unavailable. The effects of social observation may depend on the nuances of the demonstrator's behavior. The clear effects of incentive and instructions provide support for clinical interventions to reduce avoidance during exposure therapy and can serve as experimental models for their controlled investigation.

Human social defeat and approach-avoidance: Escalating social-evaluative threat and threat of aggression increases social avoidance

Basic research on avoidance by Murray Sidman laid the foundation for advances in the classification, conceptualization and treatment of avoidance in psychological disorders. Contemporary avoidance research is explicitly translational and increasingly focused on how competing appetitive and aversive contingencies influence avoidance. In this laboratory investigation, we examined the effects of escalating social-evaluative threat and threat of social aggression on avoidance of social interactions. During social-defeat learning, 38 adults learned to associate 9 virtual peers with an increasing probability of receiving negative evaluations. Additionally, 1 virtual peer was associated with positive evaluations. Next, in an approach-avoidance task with social-evaluative threat, 1 peer associated with negative evaluations was presented alongside the peer associated with positive evaluations. Approaching peers produced a positive or a probabilistic negative evaluation, while avoiding peers prevented a negative evaluation (and forfeited a positive evaluation). In an approach-avoidance task with social aggression, virtual peers gave and took money away from participants. Escalating social-evaluative threat and aggression increased avoidance, ratings of feeling threatened and threat expectancy and decreased ratings of peer favorableness. These findings underscore the potential of coupling social defeat and approach-avoidance paradigms for translational research on the neurobehavioral mechanisms of social approach-avoidance decision-making and anxiety.

The effects of warned loss magnitude and timeout duration on human avoidance behavior

This study experimentally investigated the determinants of avoidance behavior when participants are forewarned of aversive outcomes. The effects of 3 variables on avoidance behavior were examined: point-loss amount (5 levels, from 20 to 100 points), duration of timeout from positive reinforcement (5 levels, 20 to 100 s), and 3 predictive accuracy levels (100%, 50%, and 0%) of warning stimuli. Twelve participants completed 3 sessions, each comprising 25 discrete trials, that differed in predictive accuracy level. Throughout a session, a participant engaged in button press responses that were reinforced by points under a conjunctive fixed-ratio fixed-interval schedule. During each trial, a warning stimulus that indicated a loss amount and a timeout duration was presented. If the participant pressed the avoidance button, then the timeout started, otherwise the loss occurred. The trial ended with termination of timeout or an occurrence of the loss. Results showed that avoidance responses increased when the loss amount increased and decreased when the timeout duration increased. The frequency of avoidance responses was lowest when the predictive accuracy of warning stimuli was 0%. These findings demonstrated that this experimental procedure could be useful for investigating human avoidance behavior outside the laboratory.

Sensation seeking and neuroticism in fear conditioning and extinction: The role of avoidance behaviour

Maladaptive avoidance behaviour, a key symptom of anxiety-related disorders, prevents extinction learning and maintains anxiety. Individual personality traits likely influence avoidance propensity: high sensation-seeking may decrease avoidance, thereby increasing extinction, and neuroticism may have the reverse effect. However, research on this is scarce. Using a naturalistic conditioned avoidance paradigm, 163 women underwent differential fear acquisition to a conditioned stimulus (CSplus). Next, during extinction, participants could either choose a risky shortcut, anticipating shock signalled by CSplus, or a time-consuming avoidance option (lengthy detour). Across participants, increased skin conductance (SCR) acquisition learning predicted subsequent instrumental avoidance. Avoidance, in turn, predicted elevated post-extinction SCR and shock-expectancy, i.e., 'protection-from-extinction'. Mediation analyses revealed that sensation seeking decreased protection-from-extinction-both for shock-expectancy and SCR-via attenuating avoidance. Neither sensation seeking nor neuroticism were related to acquisition learning and neuroticism was neither related to avoidance nor extinction. Transcranial direct currentstimulation administered before extinction did not influence present results. Results highlight the important role of elevated avoidance propensity in fear maintenance. Results moreover provide evidence for reduced sensation-seeking and increased acquisition learning to be avoidance-driving mechanisms. Since approach-avoidance conflicts are faced by anxiety patients on a daily basis, strengthening sensation-seeking-congruent attitudes and approach behaviours may optimize individualized treatment.

Decomposing conditioned avoidance performance with computational models

Avoidance towards innocuous stimuli is a key characteristic across anxiety-related disorders and chronic pain. Insights into the relevant learning processes of avoidance are often gained via laboratory procedures, where individuals learn to avoid stimuli or movements that have been previously associated with an aversive stimulus. Typically, statistical analyses of data gathered with conditioned avoidance procedures include frequency data, for example, the number of times a participant has avoided an aversive stimulus. Here, we argue that further insights into the underlying processes of avoidance behavior could be unraveled using computational models of behavior. We then demonstrate how computational models could be used by reanalysing a previously published avoidance data set and interpreting the key findings. We conclude our article by listing some challenges in the direct application of computational modeling to avoidance data sets.

Negative reinforcement rate and persistent avoidance following response-prevention extinction

Persistent avoidance may be influenced by prior negative reinforcement rate (i.e., how effective the response is at controlling threat). In clinical settings, the effectiveness of extinction-based methods for treating anxiety-related avoidance may be impacted by prior reinforcement rate. Here, we conducted a laboratory-based treatment study to investigate the persistence of avoidance following response-prevention extinction (RPE) when prior avoidance had been differentially effective at cancelling shock. Participants in three negative reinforcement rate groups (100%, 50%, and 0%) completed a validated avoidance conditioning paradigm involving Pavlovian fear extinction, RPE, and re-extinction phases. It was hypothesised that partially reinforced avoidance would lead to diminished resistance to fear extinction following response prevention, compared to continuously- or never-reinforced avoidance. Persistent avoidance was related to prior negative reinforcement rate, with higher rates more resistant to extinction. These findings illustrate the role of reinforcement rate in the persistence of avoidance and may aid understanding of treatment relapse.

Renewal of fear and avoidance in humans to escalating threat: Implications for translational research on anxiety disorders

Exposure-based treatment for threat avoidance in anxiety disorders often results in fear renewal. However, little is known about renewal of avoidance. This multimodal laboratory-based treatment study used an ABA renewal design and an approach-avoidance (AP-AV) task to examine renewal of fear/threat and avoidance in twenty adults. In Context A, 9 visual cues paired with increases in probabilistic money loss (escalating threats) produced increases in ratings of feeling threatened and loss expectancies and skin-conductance responses (SCR). During the AP-AV task, a monetary reinforcer was available concurrently with threats. Approach produced the reinforcer or probabilistic loss, while avoidance prevented loss and forfeited reinforcement. Escalating threat produced increasing avoidance and ratings. In Context B with Pavlovian extinction, threats signaled no money loss and SCR declined. During the AP-AV task, avoidance and ratings also declined. In a return to Context A with Pavlovian threat extinction in effect during the AP-AV task, renewal was observed. Escalating threat was associated with increasing ratings and avoidance in most participants. SCR did not show renewal. These are the first translational findings to highlight renewal of avoidance in humans. Further research should identify individual difference variables and altered neural mechanisms that may confer increased risk of avoidance renewal.

Relapse of anxiety-related fear and avoidance: Conceptual analysis of treatment with acceptance and commitment therapy

Excessive fear and avoidance in relatively safe situations can lead to a narrowing of one's behavioral repertoire and less engagement with valued aspects of living. Ultimately, these processes can reach clinical levels, as seen in anxiety, trauma, and obsessive-compulsive disorders. Research on the basic behavioral processes underlying successful treatment with exposure therapy is growing, yet little is known about the mechanisms contributing to clinical relapse. Until recently, these mechanisms have largely been conceptualized in terms of Pavlovian return of fear, with relatively little research into operant processes. In the current paper, we briefly review translational research in anxiety disorders and the connections between fear and avoidance, focusing on recent work in the acquisition, extinction, and relapse of avoidance behavior and the generalization of this learning through arbitrary symbolic relations. We then introduce one possible treatment approach to mitigating clinical relapse, acceptance and commitment therapy (ACT), and provide a conceptual analysis for why ACT may be especially well-situated to address this issue. Finally, we end with potential directions for future research on treatment and relapse of anxiety disorders.

Modeling anxiety in healthy humans: a key intermediate bridge between basic and clinical sciences

Animal models of anxiety disorders are important for elucidating neurobiological defense mechanisms. However, animal models are limited when it comes to understanding the more complex processes of anxiety that are unique to humans (e.g., worry) and to screen new treatments. In this review, we outline how the Experimental Psychopathology approach, based on experimental models of anxiety in healthy subjects, can mitigate these limitations and complement research in animals. Experimental psychopathology can bridge basic research in animals and clinical studies, as well as guide and constrain hypotheses about the nature of psychopathology, treatment mechanisms, and treatment targets. This review begins with a brief review of the strengths and limitations of animal models before discussing the need for human models of anxiety, which are especially necessary to probe higher-order cognitive processes. This can be accomplished by combining anxiety-induction procedures with tasks that probe clinically relevant processes to identify neurocircuits that are potentially altered by anxiety. The review then discusses the validity of experimental psychopathology and introduces a methodological approach consisting of five steps: (1) select anxiety-relevant cognitive or behavioral operations and associated tasks, (2) identify the underlying neurocircuits supporting these operations in healthy controls, 3) examine the impact of experimental anxiety on the targeted operations in healthy controls, (4) utilize findings from step 3 to generate hypotheses about neurocircuit dysfunction in anxious patients, and 5) evaluate treatment mechanisms and screen novel treatments. This is followed by two concrete illustrations of this approach and suggestions for future studies.

From Extinction Learning to Anxiety Treatment: Mind the Gap

Laboratory models of extinction learning in animals and humans have the potential to illuminate methods for improving clinical treatment of fear-based clinical disorders. However, such translational research often neglects important differences between threat responses in animals and fear learning in humans, particularly as it relates to the treatment of clinical disorders. Specifically, the conscious experience of fear and anxiety, along with the capacity to deliberately engage top-down cognitive processes to modulate that experience, involves distinct brain circuitry and is measured and manipulated using different methods than typically used in laboratory research. This paper will identify how translational research that investigates methods of enhancing extinction learning can more effectively model such elements of human fear learning, and how doing so will enhance the relevance of this research to the treatment of fear-based psychological disorders.