Exposure to physical movements in low back pain patients: restricted effects of generalization.

Whether the effects of exposure to 1 movement generalize to another dissimilar movement was investigated in 37 patients with low back pain (15 men, 22 women). Two movements were executed twice: bending forward while standing and lifting 1 leg while lying down. During each trial, baseline pain, expected pain, and experienced pain were recorded. Similar ratings for perceived harm were obtained. Analyses revealed an initial over prediction of pain, but after exposure the overprediction was readily corrected. This exposure effect did not generalize toward another dissimilar movement. These results were only characteristic for patients with catastrophic thinking about pain. Low pain catastrophizers did not overpredict pain. There were no effects of exposure on perceived harm. Exposure may profitably be conceived of as the learning of exceptions to a general rule.     

Context specificity of conditioning and latent inhibition: Evidence for a dissociation of latent inhibition and associative interference

Conditioning may generalize from one context to another when latent inhibition (the effect on subsequent conditioning of prior unreinforced exposure to the stimulus) does not. Experiment 1 studied conditioned approach and licking by rats to a stimulus paired with the delivery of water and confirmed that latent inhibition could be abolished by a change of context, while prior aversive conditioning to the stimulus, produced by pairing it with mild shock, interfered with the acquisition of conditioned approach and licking regardless of this change of context. Thus even when conditioning and latent inhibition were measured in the same way, the former generalized across contexts, and the latter did not. Experiment 2 showed that the effects not only of unreinforced exposure to a stimulus but also of presentation of the stimulus uncorrelated with the delivery of water were confined to the context in which they occurred. Thus the generalization of conditioning from one context to another and the failure of latent inhibition to generalize cannot be attributed to the occurrence of rein-forcers during conditioning and their absence in latent inhibition. This conclusion was confirmed in Experiment 3, where animals received both aversive conditioning trials and unreinforced presentations of other stimuli in the treatment phase of the experiment, but were then conditioned to one of these stimuli paired with water. Once again, the effects of aversive conditioning transferred perfectly from one context to another, while those of unreinforced presentations did not. Latent inhibition, these results suggest, is not easily explained by supposing that animals associate an unreinforced stimulus with zero consequences and have to unlearn this association when the stimulus is then paired with a reinforcer.     

Graded exposure in vivo in the treatment of pain-related fear: a replicated single-case experimental design in four patients with chronic low back pain

The aim of this investigation was to examine the effectiveness of a graded exposure in vivo treatment with behavioural experiments as compared to usual graded activity in reducing pain-related fears, catastrophising and pain disability in chronic low back pain patients reporting substantial fear of movement/(re)injury. Included in the study were four consecutive CLBP patients who were referred for outpatient behavioural rehabilitation, and who reported substantial fear of movement/(re)injury (Tampa Scale for Kinesiophobia score>40). A replicated single-case cross-over design was used. After a no-treatment baseline measurement period, the patients were randomly assigned to one of two interventions. In intervention A, patients received the exposure first, followed by graded activity. In intervention B, the sequence of treatment modules was reversed. Sixty-three daily measures of pain-related cognitions and fears were recorded with visual analogue scales. Before and after the treatment, the following measures were taken: pain-related fear, pain catastrophising, pain control and pain disability. Using time series analysis on the daily measures of pain-related cognitions and fears, we found that improvements only occurred during the graded exposure in vivo, and not during the graded activity, irrespective of the treatment order. Analysis of the pre-post treatment differences also revealed that decreases in pain-related fear concurred with decreases in pain catastrophising and pain disability, and in half of the cases an increase in pain control. This study shows that the external validity of exposure in vivo also extends to the subgroup of chronic low back pain patients who report substantial fear of movement/(re)injury.     

Biased generalization of newly learned phonological alternations by 12-month-old infants

Previous work has suggested that learners are sensitive to phonetic similarity when learning phonological patterns (e.g.,  and ). We tested 12-month-old infants to see if their willingness to generalize newly learned phonological alternations depended on the phonetic similarity of the sounds involved. Infants were exposed to words in an artificial language whose distributions provided evidence for a phonological alternation between two relatively dissimilar sounds ([p ∼ v] or [t ∼ z]). Sounds at one place of articulation (labials or coronals) alternated whereas sounds at the other place of articulation were contrastive. At test, infants generalized the alternation learned during exposure to pairs of sounds that were more similar ([b ∼ v] or [d ∼ z]). Infants in a control group instead learned an alternation between similar sounds ([b ∼ v] or [d ∼ z]). When tested on dissimilar pairs of sounds ([p ∼ v] or [t ∼ z]), the control group did not generalize their learning to the novel sounds. The results are consistent with a learning bias favoring alternations between similar sounds over alternations between dissimilar sounds.     

Effects of varied-stimulus exposure on overpredictions of pain and behavioural performance in low back pain patients

The main objective of the present study was to investigate the benefits of exposure to a variety of movements versus exposure to the same movements on overprediction of pain and behavioural performance on a final behavioural test in a sample of chronic low back pain (CLBP) patients. Eighty-four CLBP patients were requested to perform four behavioural tests. Patients were assigned to two experimental conditions. The final behavioural test was the same for all patients. The first three behavioural tests consisted of three different movements in condition 1 and of three times the same movement in condition 2. During each behavioural test, baseline pain, expected pain and experienced pain were recorded. Furthermore, the peak torque and the variability of the produced muscle strength during the final behavioural test were assessed. Replicating and extending previous research, we found that patients overpredicted pain during a threatening behavioural test. Furthermore, pain-related fear and pain catastrophizing showed to be unique predictors of the peak torque of the final behavioural test. No support was found for our hypothesis that varied exposure facilitates generalization of exposure effects. Possible reasons for the failure to find an advantageous effect of varied-stimulus exposure and ideas for future research are discussed.     

Measuring fear of movement/(re)injury in chronic low back pain using implicit measures

Fear of movement/(re)injury is assumed to contribute to the development and maintenance of chronic low back pain (CLBP) in a subgroup of patients. Studying fear of movement/(re)injury with implicit attitude measures, without the awareness of the patient, might be a valuable addition to self-report questionnaires. The aims of the current study were to investigate whether CLBP patients demonstrate more implicit fear of movement/(re)injury than healthy controls, and whether 2 implicit measures are related to each other, and to an explicit self-report measure of fear of movement/(re)injury. A group of 66 CLBP patients and 30 healthy controls took part in this study. In addition to self-report questionnaires, fear of movement/(re)injury was implicitly assessed by the Extrinsic Affective Simon Task (EAST) and the Go-No-Go-Association Task (GNAT) that aimed to determine the association between back-stressing movements and the evaluation "threatening". On both implicit tasks it was found that neither CLBP patients nor healthy controls demonstrated implicit fear of movement/(re)injury, and that CLBP patients did not differ from healthy controls in their level of implicit fear of movement/(re)injury. In general, no associations were found between the EAST and the GNAT, or between implicitly measured and self-reported fear of movement/(re)injury. One major caveat in drawing inferences from these findings is the poor reliability of these implicit measures. Research towards the psychometric properties of these measures should first be expanded before modifying, and applying, them to more complex domains such as fear of movement/(re)injury.     

Does War Hurt? Effects of Media Exposure After Missile Attacks on Chronic Pain

This study focused on the effects of exposure to terrorist missile attacks on the physical and mental well being of chronic pain patients. In this prospective and longitudinal design, 55 chronic pain patients treated at a specialty pain clinic completed self-report questionnaires regarding their pain, depression and anxiety pre- and post a three week missile attack on the southern region of Israel. In addition, levels of direct and indirect exposure to the attacks were measured. Results of regression analyses showed that exposure to the attacks through the media predicted an increase in pain intensity and in the sensory component of pain during the pre-post war period, but did not predict depression, anxiety or the affective component of pain. These findings contribute to the understanding of the effects of terrorism on physical and emotional distress and identify chronic pain patients as a vulnerable population requiring special attention during terrorism-related stress.     

How does persistent pain develop? An analysis of the relationship between psychological variables, pain and function across stages of chronicity

The fear-avoidance model is an attempt to underscore the importance of cognitive and behavioral factors, in a chain of events linking pain to disability. However, it is not clear at what time point the psychological variables within the model begin to be prominent. The aim of this study was to investigate the role of these psychological variables in the development of a chronic musculoskeletal pain problem. Three stages of chronicity, defined by duration of pain, provided a proxy for the developmental process: <1 year (N=48), 1-3 years (N=47) and >3 years (N=89). Subjects completed questionnaires on fear of movement, catastrophizing, depression, pain and function. The results indicate that the relationship between fear of movement and function is moderated by the stage of chronicity. Regression analyses showed that fear of movement did not explain any variance in the group with pain duration <1 year. Fear of movement did explain variance in the groups with pain duration of 1-3 years and >3 years. This suggests that the time point in the development of a musculoskeletal pain problem might be an essential aspect of the importance of the relationship between psychological components and function.     

Effects of context on sweet and bitter tastes: Unrelated to sensitivity to PROP (6-npropylthiouracil)

In a double-shifting context paradigm, subjects gave magnitude estimates of the perceived intensity of qualitatively dissimilar taste substances (saccharin and quinine, sucrose and quinine) or qualitatively similar ones (saccharin and sucrose), with each pair of substances taking on different contextual sets of concentrations in different sessions. The dissimilar pairs produced substantial differential effects of context (e.g., a particular concentration of saccharin or sucrose was judged more intense than a particular quinine in one contextual setting, less intense in another), but the similar pair did not. This result accords with the hypothesis that differential context effects depend on qualitative similarity. Contrary to expectations, however, the magnitude of the context effect did not differ in tasters and nontasters of the bitter substance 6-n-propylthiouracil (PROP), groups previously shown to differ in sensitivity to bitterness in saccharin. Similarity judgments suggest that saccharin and sucrose were qualitatively alike for ail subjects, regardless of sensitivity to PROP.     

Category similarity effects in children's semantic memory retrieval

Fourth-, sixth-, and eighth-grade students were required to indicate whether or not a stimulus word belonged in either of two semantic categories that were held in memory. Each category pair was either semantically similar or semantically dissimilar. The results indicated that even for the youngest children, similar categories required less search time than dissimilar categories. It was suggested that while dissimilar categories had to be accessed successively prior to search, subjects were able to consolidate similar categories into a superordinate group which eliminated the time to shift from one category to another during search. The results were contrasted with clustering studies which have demonstrated a minimal amount of memory facilitation in children for conceptually related items over unrelated items.     

Measuring Fear of Movement/(Re)injury in Chronic Low Back Pain Using Implicit Measures

Fear of movement/(re)injury is assumed to contribute to the development and maintenance of chronic low back pain (CLBP) in a subgroup of patients. Studying fear of movement/(re)injury with implicit attitude measures, without the awareness of the patient, might be a valuable addition to self‐report questionnaires. The aims of the current study were to investigate whether CLBP patients demonstrate more implicit fear of movement/(re)injury than healthy controls, and whether 2 implicit measures are related to each other, and to an explicit self‐report measure of fear of movement/(re)injury. A group of 66 CLBP patients and 30 healthy controls took part in this study. In addition to self‐report questionnaires, fear of movement/(re)injury was implicitly assessed by the Extrinsic Affective Simon Task (EAST) and the Go‐No‐Go‐Association Task (GNAT) that aimed to determine the association between back‐stressing movements and the evaluation “threatening”. On both implicit tasks it was found that neither CLBP patients nor healthy controls demonstrated implicit fear of movement/(re)injury, and that CLBP patients did not differ from healthy controls in their level of implicit fear of movement/(re)injury. In general, no associations were found between the EAST and the GNAT, or between implicitly measured and self‐reported fear of movement/(re)injury. One major caveat in drawing inferences from these findings is the poor reliability of these implicit measures. Research towards the psychometric properties of these measures should first be expanded before modifying, and applying, them to more complex domains such as fear of movement/(re)injury.     

Correction processes in early reaching: Reaches by infants to prismatically displaced targets

Summary A comparison was made between trajectories of reaches to visual targets by 6-months-old infants, with and without lateral prismatic displacement. In the No Prism condition, the major element of the movement veered towards the target, confirming the results of Mathew and Cook (1990). In the Prism condition, the prism did not affect hand position or movement direction at the beginning of the major element, but a lateral displacement was evident by the end of the element. This is taken as evidence that shifts in trajectory during the element were not due to visual guidance. It is suggested instead that these shifts may reflect correction based upon somatic feedback about position in relation to the visually specified goal of the movement. Evidence that the hand approached the virtual target supports the suggestion that any visual guidance was confined to the approach phase of the reach. Nevertheless, it appears that visual guidance was operating at this stage, since movement direction was displaced away from the virtual target and towards the real target.     

Effects of context on sweet and bitter tastes: unrelated to sensitivity to PROP (6-n-propylthiouracil).

In a double-shifting context paradigm, subjects gave magnitude estimates of the perceived intensity of qualitatively dissimilar taste substances (saccharin and quinine, sucrose and quinine) or qualitatively similar ones (saccharin and sucrose), with each pair of substances taking on different contextual sets of concentrations in different sessions. The dissimilar pairs produced substantial differential effects of context (e.g., a particular concentration of saccharin or sucrose was judged more intense than a particular quinine in one contextual setting, less intense in another), but the similar pair did not. This result accords with the hypothesis that differential context effects depend on qualitative similarity. Contrary to expectations, however, the magnitude of the context effect did not differ in tasters and nontasters of the bitter substance 6-n-propylthiouracil (PROP), groups previously shown to differ in sensitivity to bitterness in saccharin. Similarity judgments suggest that saccharin and sucrose were qualitatively alike for all subjects, regardless of sensitivity to PROP.     

Conformity as a function of task generalization and relative competence

Subject correctness and group agreement were varied for college subjects engaged in a light discrimination task. On another task, employing multiple-choice questions about Canada, the dependent variable of conformity was assessed to examine generalization of relative competence formed on the light discrimination task. It was seen that (1) relative competence was seen to mediate conformity for a specific task (Canadian Knowledge Inventory), but did not generalize across tasks (i.e. from the light discrimination task to the Canadian Knowledge Inventory); (2) with respect to the Canadian Knowledge Inventory, subjects who perceived themselves as more competent than the group did not conform as much as those who either perceived themselves as less competent than or as competent as the group; (3) the experimental manipulations did not affect conformity, further supporting the findings that perceived competence does not generalize across classes of tasks; (4) females conformed more than males: and (5) nonsuspicious subjects conformed more than suspicious subjects.     

Understanding individual differences in lifting mechanics: Do some people adopt motor control strategies that minimize biomechanical exposure

The movement strategy an individual uses to complete a lift can influence the resultant biomechanical exposure on their low back. We hypothesize that some lifters may choose a motor control strategy to minimize exposure to the low back, where others may not. Lower magnitudes of exposure to the low back coupled with less variability in lift-to-lift exposure and in features of movement strategy related to biomechanical exposure would support that such lifters consider minimizing exposure in their motor control strategy. We tested this hypothesis by investigating if differences in variability of low back exposure measures, as well as features of movement strategy related to resultant low back exposures differed across lifters. Twenty-eight healthy adults participated in the study where ten repetitions of a lifting task with the load scaled to 75% of participant's one-repetition maximum were completed. In all trials, whole-body kinematics and ground reaction forces were collected. Lifters were grouped as low, moderate or high relative exposure based on low back flexion angles and normalized L4/L5 extensor moments when lifting. Principal component analysis was used to identify independent movement strategy features, and statistical testing determined which features differed between high and low exposure lifts. Variability in low back exposures and movement features associated with relative biomechanical exposure were compared across lifter classifications. Significantly less variability was observed in low back exposures among the low exposure lifter group. Additionally, a trend towards lower variability in movement features associated with relative biomechanical exposure was also observed in low exposure lifters. These findings provide initial support for the hypothesis that some lifters likely define a motor control strategy that considers minimizing biomechanical exposure in addition to completing the lift demands. Future work should explore how state and trait-based factors influence an individual to consider biomechanical exposure within their motor control strategy in lifting.     

TEACHING BETWEEN-CLASS generalization OF TOY PLAY BEHAVIOR TO HANDICAPPED CHILDREN

In this study, young children with severe and moderate handicaps were taught to generalize play responses. A multiple baseline across responses design, replicated with four children, was used to assessthe effects of generalization training within four sets of toys on generalization to untrained toys from four other sets. The responses taught were unique for each set of toys. Acrossthe four participants, training to generalize within-toy sets resulted in complete between-class generalization in 11 sets, partial generalization in 3 sets, and no generalization in 2 sets. No generalization occurred to another class of toys that differed fromthe previous sets in that they produced a reaction tothe play movement (e.g., pianos). Implications for conducting research using strategies based on class interrelationships in training contexts are discussed.     

Effects of morphine and naloxone upon the reactions of rats to a heat stressor

Five experiments used rats to examine the conditioned hypoalgesia induced by exposure to a heated floor. Experiments 1 and 2 demonstrated that this hypoalgesia is mediated by non-opioid mechanisms of pain control, as evidenced by insensitivity to the opioid antagonist naloxone and by the absence of cross-tolerance with the opioid agonist morphine. Although non-opioid in nature, the acquisition of conditioned hypoalgesia was facilitated by naloxone and impaired by morphine (Experiments 3 and 4). These effects did not appear to be due to an opioid regulation of pain. (1) Pairing morphine with the heated floor attenuated acquisition in drug-tolerant rats. (2) This attenuation by morphine was removed when naloxone was given after exposure to the heated floor. (3) Conditioning was facilitated when naloxone was given after exposure to the heated floor (Experiment 5). The results were discussed in terms of an opioid regulation of (a) surprise, (b) arousal of an aversive motivational system, and (c) the affective component of pain.     

Conjugate lateral eye movement and latency of verbal response to arithmetic questions.

24 left movers, 24 right movers and 24 mixed movers, categorized on the basis of their conjugate lateral eye movements, were measured on latency of verbal response to arithmetic questions. The predicted superiority of right movers in speed of response did not occur nor did interference with habitual direction of conjugate lateral eye movement affect results. However, the mixed group took longer to response to a second series of questions than did the left and right movers. This post hoc finding may indicate inefficient hemispheric competition within the mixed group when subjects are asked to add another task to that of arithmetic problem-solving.     

Chronic pain as a posture towards the world

This article discusses what chronic pain is “about”, what the intentional object is of pain, and what is the intentional relation like? My approach is based on Maurice Merleau‐Ponty’s phenomenology, with an aim is to understand a two‐way relationship: how the sufferers bestow meaning on chronic pain, and how pain, on the other hand, signifies peoples’ life. In contrast to biomedical and cognitive‐behavioral theories, chronic pain is not only meaningful, but as an intentional emotion as well; it does not simply “happen” in the nervous system. I analyzed meanings assigned to pain through the narratives of three patients with chronic pain. Pain is described as creating a discontinuity in the patient’s Lebenswelt at the narrative level. When attempting to find meaning to their pain, patients point both to everyday life and biomedical referents. The structure of bestowing meaning is, metaphorically, like a necklace with everyday world and biomedical interpretations strung like beads, one after the other. The intentional object of pain, on the contrary, is constituted of the patients’ world in its wholeness. My results don’t confirm Drew Leder’s idea of disrupted intentionality, but underline directness as the basic relation of human experience also in case of pain and disease. Pain in itself is an e‐movere, an intense passionate movement, an intentional relation with and a bodily posture taken towards the world.