Generalization of Costly Pain-Related Avoidance Based on Real-Life Categorical Knowledge.

Avoiding activities posing bodily threat is adaptive. However, spreading of avoidance to safe activities may cause functional disability in people with chronic pain. We investigated whether costly pain-related avoidance would generalize from one activity to another on the basis of real-life categorical knowledge in 40 pain-free people (30 female; mean age = 25 years; university students and public of Maastricht, The Netherlands). In a computer task, participants moved a joystick to complete activities from two categories (gardening and cleaning). During activities from the avoidance category, pain could be avoided at the cost of task efficiency by deviating from a short, pain-associated joystick movement. Activities from the safe category were never painful. Subsequently, we tested generalization of avoidance to novel pain-free activities from both categories. Participants generalized avoidance to novel activities from the avoidance category despite the novel activities not being paired with pain and despite avoidance costs, suggesting that costly (pain-related) avoidance generalizes from one activity to another on the basis of category knowledge and can thus be wide reaching, creating detrimental consequences.

The Perceived Opportunity to Avoid Pain Paradoxically Increases Pain-Related Fear Through Increased Threat Appraisals.

BACKGROUND: Although pain-related avoidance is mainly intended to reduce the accompanying anticipatory fear, avoidance behavior may paradoxically increase fear when a previous avoidance response is no longer available, suggesting that there is a bidirectional relationship between pain-related fear and avoidance. PURPOSE: We hypothesized that avoidance can serve as a source of information that fuels irrational pain-related threat appraisals, which, in turn, increases pain-related fear. METHODS: Participants (N = 66) were exposed to a painful heat stimulus and randomly assigned to the avoidance or control group. They were instructed to avoid the full heat intensity by pressing a stop button in the presence of a stop cue. Only avoidance group participants received a stop cue and were allowed to press the stop button, while control group participants received the same instructions but never had the opportunity to avoid the full heat intensity. In reality and unknown to participants, the intensity and duration of the heat stimulus was independent of the avoidance response. In the subsequent test phase, the avoidance response was unavailable for both groups. We measured pain-related fear, threat appraisals/harmfulness, and pain intensity. RESULTS: In line with our expectations, pain-related fear levels were higher when the avoidance response was no longer available compared to those when the avoidance response was available. Increased threat appraisals mediated the relationship between avoidance behavior and increased pain-related fear. CONCLUSIONS: The perceived opportunity to avoid increased pain-related fear through threat appraisals, suggesting a more complicated relationship between pain-related fear, threat appraisals, and avoidance behavior than the unidirectional relationships proposed in the fear-avoidance model. Clinical implications are discussed.

Can positive affect attenuate (persistent) pain? State of the art and clinical implications.

PURPOSE OF REVIEW: Pain is an intense experience that can place a heavy burden on peoples' lives. The identification of psychosocial risk factors led to the development of effective pain treatments. However, effect sizes are modest. Accumulating evidence suggests that enhancing protective factors might also impact on (well-being despite) pain. Recent findings on positive affect (interventions) towards pain-related outcomes will be reviewed, and new avenues for treatment of persistent pain will be discussed. RECENT FINDINGS: Positive affect significantly attenuates the experience of pain in healthy and clinical populations. Positive affect interventions effectively reduce pain sensitivity and bolster well-being despite pain. Through both psychological and (neuro-)biological pathways, but also through its effect on central treatment processes such as inhibitory learning, positive affect can optimize the efficacy of existing treatments. Comprehensive understanding of the unique roles and dynamic interplay of positive and negative affect in moderating pain may optimize the treatment of (persistent) pain.

Confidence intervals for single-case effect size measures based on randomization test inversion.

In the current paper, we present a method to construct nonparametric confidence intervals (CIs) for single-case effect size measures in the context of various single-case designs. We use the relationship between a two-sided statistical hypothesis test at significance level α and a 100 (1 - α) % two-sided CI to construct CIs for any effect size measure θ that contain all point null hypothesis θ values that cannot be rejected by the hypothesis test at significance level α. This method of hypothesis test inversion (HTI) can be employed using a randomization test as the statistical hypothesis test in order to construct a nonparametric CI for θ. We will refer to this procedure as randomization test inversion (RTI). We illustrate RTI in a situation in which θ is the unstandardized and the standardized difference in means between two treatments in a completely randomized single-case design. Additionally, we demonstrate how RTI can be extended to other types of single-case designs. Finally, we discuss a few challenges for RTI as well as possibilities when using the method with other effect size measures, such as rank-based nonoverlap indices. Supplementary to this paper, we provide easy-to-use R code, which allows the user to construct nonparametric CIs according to the proposed method.

Bogus visual feedback alters onset of movement-evoked pain in people with neck pain.

Pain is a protective perceptual response shaped by contextual, psychological, and sensory inputs that suggest danger to the body. Sensory cues suggesting that a body part is moving toward a painful position may credibly signal the threat and thereby modulate pain. In this experiment, we used virtual reality to investigate whether manipulating visual proprioceptive cues could alter movement-evoked pain in 24 people with neck pain. We hypothesized that pain would occur at a lesser degree of head rotation when visual feedback overstated true rotation and at a greater degree of rotation when visual feedback understated true rotation. Our hypothesis was clearly supported: When vision overstated the amount of rotation, pain occurred at 7% less rotation than under conditions of accurate visual feedback, and when vision understated rotation, pain occurred at 6% greater rotation than under conditions of accurate visual feedback. We concluded that visual-proprioceptive information modulated the threshold for movement-evoked pain, which suggests that stimuli that become associated with pain can themselves trigger pain.

The effect of threat information on acquisition, extinction, and reinstatement of experimentally conditioned fear of movement-related pain.

OBJECTIVE: The experiential acquisition of pain-related fear has been demonstrated by pairing a painful electrocutaneous stimulus pain-US; unconditioned pain stimulus) with one movement (CS+; conditioned stimulus) but not with another (CS-). However, it is expected that during acquisition through direct experience, pain-related fear can be intensified or weakened by verbally/visually transmitted information about the pain and its meaning. METHOD: Participants received threatening information (US-inflation), safety information (US-deflation), or no information about the pain-US (US-same). Additionally, we measured return of fear after a reinstatement procedure: two unsignaled pain-USs were presented in the experimental groups, but not in the control groups. RESULTS: We replicated the acquisition and extinction of experimentally induced fear of movement-related pain in healthy subjects both in the verbal reports and the eye-blink startle measures. Two reinstating pain-US presentations led to a differential return of self-reported fear and a nondifferential return of fear in the eye-blink startle responses. Although, we failed to find an effect of verbal/visual information regarding the meaning of the pain-US on the acquisition, extinction, or reinstatement of pain-related fear, we did observe a pain sensitization effect over time suggesting that our threat manipulation induced an increase of perceived threat in all groups. CONCLUSION: The results suggest that our threat manipulation might not have worked or that it was not sensitive enough to yield group-specific effects. We replicated acquisition, extinction, and return of experimentally conditioned fear of movement-related pain, but the threat manipulation failed to generate any additional effects.

High-Anxious People Generalize Costly Pain-Related Avoidance Behavior More to Novel Safe Contexts Compared to Low-Anxious People.

Pain-related avoidance is adaptive when there is a bodily threat, but when it generalizes to safe movements/situations, it may become disabling. Both subclinical anxiety-a vulnerability marker for chronic pain-and chronic pain are associated with excessive fear generalization to safe stimuli/situations. Previous research focused mainly on passive fear correlates (psychophysiological arousal and self-reports) leaving avoidance behavior poorly understood. Therefore, we tested whether high-anxious individuals generalize their pain-related avoidance behavior more to novel, safe contexts than low-anxious people. In a robotic-arm-reaching task, both groups (low vs high trait anxiety) performed 1 of 3 movements to reach a target. In the threat context (black background), a painful stimulus could be partly/completely prevented by performing more effortful trajectories (longer and more force needed); in the safe context (white background), no pain occurred. Generalization of avoidance was tested in 2 novel contexts (light/dark gray backgrounds). We assessed pain expectancy, pain-related fear, startle eyeblink responses for all trajectories, and avoidance behavior (ie, maximal deviation from shortest trajectory). Results indicated that differential fear and expectancy selectively generalized to the novel context resembling the original threat context in both groups. Interestingly and in contrast with the verbal reports, high-anxious participants avoided more in the novel context resembling the original safe context, but not in the 1 resembling the threat context. No generalization emerged in the startle data. Because excessive pain-related avoidance specifically may cause withdrawal from daily life activities, these findings suggest that high-anxious individuals may be vulnerable to developing chronic pain disability. PERSPECTIVE: This paper shows that high-anxious people do not overgeneralize pain-related fear and pain expectancy learned in a threat context more to novel, safe contexts than low-anxious individuals, but that they do avoid more in those contexts. These findings suggest that high-anxious individuals may be vulnerable to developing chronic pain disability.

Rewarding Approach Behaviour Attenuates the Return of Pain-Related Avoidance After Successful Extinction with Response Prevention.

After successful exposure treatment for chronic pain, pain-related fear and avoidance may return, i.e., relapse may occur. This return of fear and avoidance may be modulated by various post-treatment factors. In this study, we aimed to investigate two potential factors that may affect return of fear and avoidance, i.e. cognitive load and rewarding approach behaviour. In an operant pain-related avoidance conditioning paradigm, healthy pain-free volunteers first learned to fear and avoid an arm-reaching movement that was often paired with painful electrocutaneous stimulation (T1), by performing alternative movements that were less often (T2) or never (T3) paired with pain. During extinction with response prevention, participants were only allowed to perform T1, and pain was omitted. To model relapse, two unexpected painful stimuli were presented (i.e., reinstatement manipulation), after which participants could freely choose among the three arm-reaching movements again. During test, the Low Load group performed an additional easy digit task, whereas the High Load group performed a more cognitively demanding digit task. The Reward group performed the demanding digit task, whilst being rewarded to perform T1. Results showed that pain-related fear and avoidance returned, irrespective of cognitive load imposed. When participants were rewarded to approach T1, however, the return of avoidance, but not fear, was attenuated. Our findings suggest that engaging in rewarding activities may facilitate the maintenance of treatment outcomes, and provide additional support to the growing body of literature indicating a divergent relationship between fear and avoidance. PERSPECTIVE: Results of this experiment suggest that engaging in rewarding activities may optimize exposure treatment for chronic pain, by dampening the return of pain-related avoidance - though not of pain-related fear - after extinction.

The influence of threat on visuospatial perception, affordances, and protective behaviour: A systematic review and meta-analysis.

Perception has been conceptualised as an active and adaptive process, based upon incoming sensory inputs, which are modified by top-down factors such as cognitions. Visuospatial perception is thought to be scaled based on threat, with highly threatening objects or contexts visually inflated to promote escape or avoidance behaviours. This meta-analytical systematic review quantified the effect and evidence quality of threat-evoked visuospatial scaling, as well as how visuospatial scaling relates to affordances (perceived action capabilities) and behavioural avoidance/escape outcomes. Databases and grey literature were systematically searched inclusive to 10/04/24. Studies were assessed with a customised Risk of Bias form and meta-analysis was performed using a random-effects model. 12,354 records were identified. Of these, 49 experiments (n = 3027) were included in the review. There was consistent evidence that threat the of height influenced contextual perception (g = 0.66, 95% CI: 0.45, 0.88) and affordances (g = -0.43, 95% CI: -0.84, -0.03). Threatening objects were viewed as larger (g = 0.76, 95% CI: 0.26, 1.26) and as closer (g = 0.30, 95% CI: 0.17, 0.42). Bodily threat (pain) yielded conflicting effects on visuospatial perception/affordances. We conclude that threat may influence visuospatial perception and affordances. However, since behavioural measures were poorly reported, their relationship with visuospatial perception/affordances remains elusive.

Fear Learning in Genital Pain: Toward a Biopsychosocial, Ecologically Valid Research and Treatment Model.

Although fear learning mechanisms are implicated in the development, maintenance, exacerbation, and reduction of genital pain, systematic research on how fear of genital pain emerges, spreads, persists, and reemerges after treatment is lacking. This paper provides an overview of the literature on pain-related fear, integrates the ideas on learning and sexual arousal responding, and specifies the pathways through which compromised learning may contribute to the development and persistence of genital pain. In order to refine theories of genital pain and optimize treatments, we need to adopt a biopsychosocial framework to pain-related fear learning and uncover potential moderators that shape individual trajectories. This involves examining the role of physiological processes, subjective experiences, as well as partner and relational cues in fear acquisition, excessive generalization and impaired safety learning, extinction of fear, counterconditioning, and return of fear. Recent methodological advances in fear conditioning and sex research are promising to enable more symptom-specific and ecologically valid experimental paradigms.

The effect of experimentally induced positive affect on the generalization of pain-related avoidance and relief.

Avoiding pain-associated activities can prevent tissue damage. However, when avoidance spreads excessively (or overgeneralizes) to safe activities, it may culminate into chronic pain disability. Gaining insight into ways to reduce overgeneralization is therefore crucial. An important factor to consider in this is relief, as it reinforces avoidance behavior and therefore may be pivotal in making avoidance persist. The current study investigated whether experimentally induced positive affect can reduce generalization of pain-related avoidance and relief. We used a conditioning task in which participants (N = 50) learned that certain stimuli were followed by pain, while another was not. Subsequently, they learned an avoidance response that effectively omitted pain with one stimulus, but was ineffective with another. Next, one group of participants performed an exercise to induce positive affect, while another group performed a control exercise. During the critical generalization test, novel stimuli that were perceptually similar to the original stimuli were presented. Results showed that both avoidance and relief generalized to novel stimuli, thus replicating previous work. However, increasing positive affect did not reduce generalization of avoidance, nor relief.

Generalization of pain-related avoidance behavior based on de novo categorical knowledge.

ABSTRACT: People with chronic pain often fear and avoid movements and activities that were never paired with pain. Safe movements may be avoided if they share some semantic relationship with an actual pain-associated movement. This study investigated whether pain-associated operant responses (movements) can become categorically associated with perceptually dissimilar responses, thus motivating avoidance of new classes of safe movements-a phenomenon known as category-based avoidance generalization. Using a robotic arm, 2 groups were trained to categorize arm movements in different ways. Subsequently, the groups learned through operant conditioning that an arm movement from one of the categories was paired with a high probability of pain, whereas the others were paired with either a medium probability of pain or no pain (acquisition phase). Self-reported pain-related fear and pain expectancy were collected as indices of fear learning. During a final generalization test phase, the movements categorically related to those from the acquisition phase were made available but in the absence of pain. Results showed that the generalization of outcome measures depended on the categorical connections between arm movements, ie, the groups avoided and feared the novel generalization movement categorically related to the pain-associated acquisition movement, depending on how they had previously learned to categorize the movements. This suggests that operant pain-related avoidance can generalize to safe behaviors, which are not perceptually, but categorically, similar to a pain-associated behavior. This form of pain-related avoidance generalization is problematic because category-based relations can be extremely wide reaching and idiosyncratic. Thus, category-based generalization of operant pain-related avoidance merits further investigation.

Modulation of attention to pain by goal-directed action: a somatosensory evoked potentials approach.

Background: Attentional processes are modulated by current goal pursuit. While pursuing salient cognitive goals, individuals prioritize goal-related information and suppress goal-irrelevant ones. This occurs in the context of pain too, where nonpain cognitive goal pursuit was found to have inhibitory effects on pain-related attention. Crucially, how pursuing nonpain motor goals affects pain-related somatosensory attention is still unknown. The aim of this study was to investigate whether nonpain motor goal pursuit would attenuate pain-related somatosensory attention. Methods: Healthy volunteers (N = 45) performed a robotic arm conditioning task where movements were paired with conflicting (pain and reward), threatening (only pain) or neutral (no pain and no reward) outcomes. To increase the motivational value of pursuing the nonpain motor goal, in the conflicting condition participants could receive a reward for a good motor performance. To examine somatosensory attention during movement, somatosensory evoked potentials (SEPs; N120 and P200) were obtained in response to innocuous tactile stimuli administered on a pain-relevant or pain-irrelevant body location. We expected that the threat of pain would enhance somatosensory attention. Furthermore, we expected that the possibility of getting a reward would inhibit this effect, due to pain-reward interactions. Results: Against our predictions, the amplitude of the N120 did not differ across movement types and locations. Furthermore, the P200 component showed significantly larger SEPs for conflicting and threat movements compared to neutral, suggesting that the threat of pain increased somatosensory attention. However, this effect was not modulated by nonpain motor goal pursuit, as reflected by the lack of modulation of the N120 and P200 in the conflicting condition as compared to the threat condition. This study corroborates the idea that pain-related somatosensory attention is enhanced by threat of pain, even when participants were motivated to move to obtain a reward.

Understanding Discrepancies in a Person's Fear of Movement and Avoidance Behavior: A Guide for Musculoskeletal Rehabilitation Clinicians Who Support People With Chronic Musculoskeletal Pain.

BACKGROUND: Generic self-report measures do not reflect the complexity of a person's pain-related behavior. Since variations in a person's fear of movement and avoidance behavior may arise from contextual and motivational factors, a person-centered evaluation is required-addressing the cognitions, emotions, motivation, and actual behavior of the person. CLINICAL QUESTION: Most musculoskeletal rehabilitation clinicians will recognize that different people with chronic pain have very different patterns of fear and avoidance behavior. However, an important remaining question for clinicians is "How can I identify and reconcile discrepancies in fear of movement and avoidance behavior observed in the same person, and adapt my management accordingly?" KEY RESULTS: We frame a clinical case of a patient with persistent low back pain to illustrate the key pieces of information that clinicians may consider in a person-centered evaluation (ie, patient interview, self-report measures, and behavioral assessment) when working with patients to manage fear of movement and avoidance behavior. CLINICAL APPLICATION: Understanding the discrepancies in a person's fear of movement and avoidance behavior is essential for musculoskeletal rehabilitation clinicians, as they work in partnership with patients to guide tailored approaches to changing behaviors. J Orthop Sports Phys Ther 2023;53(5):1-10. Epub: 9 March 2023. doi:10.2519/jospt.2023.11420.

The Effect of Observing High or Low Pain on the Development of Central Sensitization.

It is unknown whether watching other people in high pain increases mechanical hypersensitivity induced by pain. We applied high-frequency electrical stimulation (HFS) on the skin of healthy volunteers to induce pinprick mechanical hypersensitivity. Before HFS participants were randomly allocated to 2 groups: in the low pain group, which was the control condition, they watched a model expressing and reporting lower pain scores, in the high pain group the model expressed and reported higher scores. The 2 videos were selected on the basis of a pilot/observational study that had been conducted before. We tested the differences in perceived intensity of the HFS procedure, in the development of hypersensitivity and the role of fear and empathy. The high pain group reported on average higher pain ratings during HFS. The perceived intensity of hypersensitivity, but not the unpleasantness or the length of the area was higher in the high pain group. Our results suggest that watching a person expressing more pain during HFS increases one's own pain ratings during HFS and may weakly facilitate the development of secondary mechanical hypersensitivity, although this latter result needs replication. PERSPECTIVE: Observing a person in high pain can influence the perceived pain intensity of a procedure leading to secondary mechanical hypersensitivity, and has a weak effect on hypersensitivity itself. The role of fear remains to be elucidated.

Reliability and Validity of the Avoidance of Daily Activities Photo Scale for Patients With Shoulder Pain (ADAP Shoulder Scale).

OBJECTIVE: The Avoidance of Daily Activities Photo Scale for Patients With Shoulder Pain (ADAP Shoulder Scale) was developed to assess pain-related avoidance behavior during daily activities in people with shoulder pain. However, its measurement properties must be verified according to international guidelines. As such, this study investigated the following 4 measurement properties of the ADAP Shoulder Scale: reliability, measurement errors, convergent validity, and floor and ceiling effects. METHODS: The sample comprised 100 individuals with chronic shoulder pain (43 men and 57 women; mean duration of symptoms of 29.7 [SD = 89.0] months; mean age of 44.9 [SD = 15.9] years). The mean test-retest reliability range was 5 days via the intraclass correlation coefficient (ICC). Measurement errors included the standard error of measurement and the minimal detectable change. Convergent validity was analyzed by applying the Pearson correlation with the Tampa Scale for Kinesiophobia, Pain Catastrophizing Scale, and Shoulder Pain and Disability Index. RESULTS: The ADAP Shoulder Scale showed excellent test-retest reliability, both in all domains and in the total score [ICC(2,1) = 0.94; 95% CI = 0.92-0.96]. The standard errors of measurement for the free-movement, high-effort, and self-care domains were 8.1%, 6.0%, and 7.6%, respectively. The minimal detectable change for the total score of the ADAP Shoulder Scale was 16.0%. The total score of the ADAP Shoulder Scale was low to moderately correlated with the total scores of the Tampa Scale for Kinesiophobia (r = 0.52), Pain Catastrophizing Scale (r = 0.30), and Shoulder Pain and Disability Index (r = 0.72). No floor or ceiling effects were detected in the total score. CONCLUSION: The ADAP Shoulder Scale is a reliable, valid instrument for assessing avoidance behavior in adults who have chronic shoulder pain and are not athletes. IMPACT: This study provides evidence that the ADAP Shoulder Scale is appropriate for clinical and practical use in people with chronic shoulder pain.

Get Your Head in the Game: A Replicated Single-Case Experimental Design Evaluating the Effect of a Novel Virtual Reality Intervention in People With Chronic Low Back Pain.

Chronic low back pain (CLBP) is a leading cause of disability worldwide. Contemporary treatment of CLBP is suboptimal, with small-moderate effect sizes and high relapse rates. Virtual reality (VR) is an increasingly accessible technology that can improve adherence to exercise programs through gamification. Using VR to facilitate exercise adherence and enjoyment may improve the clinical outcomes. This study aimed to evaluate the effects of a gamified VR graded activity intervention in people with CLBP, using commercially available and bespoke VR programs. A sequentially replicated, multiple-baseline, randomized AB single-case experimental design was undertaken in 10 people with CLBP. Outcomes were assessed daily and included pain intensity (primary) and pain catastrophizing, pain-related fear, and anxiety/worry (secondary). The effect of the intervention on the primary outcome was evaluated using a multilevel-model, nonparametric randomization test. The VR graded activity intervention resulted in a significant reduction in pain intensity (effect estimate = -1.0, standard error = .27, P < .0011) with 4 participants achieving ≥30% pain reduction (minimum important change). There was a significant effect of the intervention on pain catastrophizing but not pain-related fear or anxiety/worry measures. These findings provide preliminary support for a VR graded activity program to reduce pain in people with CLBP. PERSPECTIVE: This novel, VR graded activity intervention reduced pain intensity and catastrophizing in people with CLBP. The intervention also had high adherence and enjoyment. Given that this intervention involved 2 freely available VR programs, it can be easily translated into clinical practice.

Pain and avoidance: The potential benefits of imagining your best possible self.

Positive affect is hypothesized to improve safety learning taking place during extinction (i.e., the core mechanism of exposure treatment), therefore improving the maintenance of treatment outcomes. We investigated whether positive affect during extinction attenuates the subsequent return of pain-related avoidance and fear. In an operant pain-related avoidance conditioning paradigm, sixty healthy volunteers performed arm-reaching movements using a robotic arm. During acquisition, they learned to avoid an easy but painful movement (T1) by choosing more effortful movements that were sometimes (T2) or never (T3) painful. Then, the Positive affect group wrote about and imagined their best possible self, which is known to induce positive affect, whereas the Control group wrote about and imagined a typical day. During extinction with response prevention (RPE), participants were only allowed to perform T1, which was no longer paired with pain. Next, two painful stimuli were presented when participants were not moving (i.e., reinstatement manipulation). During test, all movements were available, and we examined whether fear and avoidance of the previously painful movements would re-emerge. Pain-related avoidance returned in both groups, but the two groups did not differ herein. The Positive affect group reported increased positive affect, though not more than the Control group. Nevertheless, they generalized the learned safety of T1 to the other movements during RPE, whereas they also retrospectively rated the pain as less intense and less unpleasant. These results add to the literature of positive affect as a resilience factor.

Know Your Movements: Poorer Proprioceptive Accuracy is Associated With Overprotective Avoidance Behavior.

Pain-related avoidance of movements that are actually safe (ie, overprotective behavior) plays a key role in chronic pain disability. Avoidance is reinforced through operant learning: after learning that a certain movement elicits pain, movements that prevent pain are more likely to be performed. Proprioceptive accuracy importantly contributes to motor learning and memory. Interestingly, reduced accuracy has been documented in various chronic pain conditions, prompting the question whether this relates to avoidance becoming excessive. Using robotic arm-reaching movements, we tested the hypothesis that poor proprioceptive accuracy is associated with excessive pain-related avoidance in pain-free participants. Participants first performed a task to assess proprioceptive accuracy, followed by an operant avoidance training during which a pain stimulus was presented when they performed one movement trajectory, but not when they performed another trajectory. During a test phase, movements were no longer restricted to 2 trajectories, but participants were instructed to avoid pain. Unbeknownst to the participants, the pain stimulus was never presented during this phase. Results supported our hypothesis. Furthermore, exploratory analyses indicated a reduction in proprioceptive accuracy after avoidance learning, which was associated with excessive avoidance and higher trait fear of pain. PERSPECTIVE: This study is the first to show that poorer proprioceptive accuracy is associated with excessive pain-related avoidance. This finding is especially relevant for chronic pain conditions, as reduced accuracy has been documented in these populations, and points toward the need for research on training accuracy to tackle excessive avoidance.

Indoor or Outdoor? Generalization of Costly Pain-Related Avoidance Behavior to Conceptually Related Contexts.

When pain persists beyond healing time and becomes a "false alarm" of bodily threat, protective strategies, such as avoidance, are no longer adaptive. More specifically, generalization of avoidance based on conceptual knowledge may contribute to chronic pain disability. Using an operant robotic-arm avoidance paradigm, healthy participants (N = 50), could perform more effortful movements in the threat context (eg, pictures of outdoor scenes) to avoid painful stimuli, whereas no pain occured in the safe context (eg, pictures of indoor scenes). Next, we investigated avoidance generalization to conceptually related contexts (ie, novel outdoor/indoor scenes). As expected, participants avoided more when presented with novel contexts conceptually related to the threat context than in novel exemplars of the safe context. Yet, exemplars belonging to one category (outdoor/indoor scenes) were not interchangeable; there was a generalization decrement. Posthoc analyses revealed that contingency-aware participants (n = 27), but not non-aware participants (n = 23), showed the avoidance generalization effect and also generalized their differential pain-expectancy and pain-related fear more to novel background scenes conceptually related to the original threat context. In contrast, the fear-potentiated startle response was not modulated by context. PERSPECTIVE: This article provides evidence for contextual modulation of avoidance behavior and its generalization to novel exemplars of the learned categories based on conceptual relatedness. Our findings suggest that category-based generalization is a plausible mechanism explaining why patients display avoidance behavior in novel situations that were never directly associated with pain.