Psychological mechanisms of medically unexplained symptoms: an integrative conceptual model

Theories of medically unexplained illness based on the concepts of dissociation, conversion, and somatization are summarized. Evidence cited in support of these theories is described and the conceptual strengths and shortcomings of each approach are considered. It is argued that each of these approaches adds to the understanding of unexplained illness but that none is able to provide a comprehensive explanation of the phenomenon. An integrative conceptual model of unexplained illness based on cognitive psychological principles is then presented. This model attempts to combine existing theoretical approaches within a single explanatory framework, extending previous theory by explaining how compelling symptoms can exist in the absence of organic pathology. The clinical and empirical implications of the model are then considered.     

Psychometric evaluation of the behavioral inhibition/behavioral activation scales in a large sample of outpatients with anxiety and mood disorders

The latent structure, reliability, and validity of the Behavioral Inhibition/Behavioral Activation Scales (BIS/BAS; C. L. Carver and T. L. White, 1994) were examined in a large sample of outpatients (N = 1,825) with anxiety and mood disorders. Four subsamples were used for exploratory and confirmatory factor analyses. In addition to generally upholding a latent structure found previously in nonclinical samples, results indicated measurement invariance of the BIS/BAS between genders and a higher order structure of the BAS scales. Convergent and discriminant validity of the BIS/BAS were supported by findings that the subscales correlated most strongly with measures of neighboring personality constructs (e.g., BIS with neuroticism, BAS with positive affect) than with measures of current anxiety and depression symptoms. Overall, the results support the psychometric properties of the BIS/BAS in this clinical sample.     

In sight but out of mind: do competing views test the limits of perception without awareness?

Over a century's worth of research suggests that "perception" without awareness is a genuine phenomenon. However, relatively little research has explored the question of whether all visually presented information activates representations in long term memory without awareness. Two experiments explored the use of a figure-ground display consisting of competing views in which one view dominates the other such that subjects are (initially) unaware of the non-dominant view. Neither experiment provided evidence that the non-dominant view (an embedded word) activated its representation in long term memory when the subject failed to report being aware of the embedded word in that priming was not seen on a subsequent stem completion task. In contrast, priming was seen when subjects reported being aware of the embedded word. It is suggested that two competing figure-ground relations are not concurrently computed unconsciously.     

GENDER AS A FACTOR IN THE RESPONSE OF THE LAW-ENFORCEMENT SYSTEM TO VIOLENCE AGAINST PARTNERS

…it is the worst oppression, that is done by colour of justice --Sir Edward Coke A sign that says "men only" looks very different on a bathroom door than on a courthouse door. --U.S. Supreme Court Justice Thurgood Marshall "Is Parkinson's the toughest opponent you've ever faced, Muhammed?" someone asked. "Toughest was my first wife," he said. --Former World Heavyweight Boxing Champion Muhammed Ali A great deal of sociological evidence has been collected in the past three decades on the prevalence of abuse among adult heterosexual partners in domestic relationships of some degree of permanence. Partly as a result of this information, partner abuse has been identified as an important social ill that must be addressed aggressively through public-awareness campaigns, the funding of a broad range of support services, and the re-training of law-enforcement authorities--including police, prosecutors, and judges. However, in at least one important respect, these policy initiatives diverge substantially from what the sociological data, which ostensibly motivates them, would indicate: they have been, to date, overwhelmingly gender specific. That is, partner abuse is routinely portrayed and acted upon as though it were almost exclusively about men abusing and victimizing innocent women and, by extension, their children--despite the overwhelming sociological evidence that a significant amount of abuse is also suffered by male partners. Persistent anecdotal reports from victims and even some participants in the law-enforcement system suggest that this ideological emphasis on the male as perpetrator has had a deleterious effect on the impartial administration of justice, resulting in men being treated much more harshly than women who are accused of partner violence. This study attempts to determine whether the anecdotes are scientifically supportable.     

Adjustment to chronic low back pain--the relative influence of fear-avoidance beliefs, catastrophizing, and appraisals of control

The present study investigated the relative extent to which patients' adjustment to chronic low back pain (CLBP) was influenced by their fear-avoidance beliefs, their tendency to catastrophize, and their appraisals of control. Eighty-three CLBP patients completed a series of self-report measures before participating in a physical therapist-led intervention. Hierarchical multiple regression analyses revealed that patients' perceptions of their ability to decrease pain explained a small, but statistically significant, proportion of the variance in pain intensity. In addition, patients' levels of catastrophizing, as well as their fear-avoidance beliefs about both work and physical activity, were independently associated with levels of disability. Interestingly, however, when exploring the relative predictive utility of these three psychological factors, it became evident that fear-avoidance beliefs about physical activity (FABs-PA) were the only significant predictor of patients' disability. Specifically, those patients who exhibited higher levels of FABs-PA tended to report greater levels of disability, even after adjusting for age, sex and pain intensity.     

A multiple-goal, multilevel model of feedback effects on the regulation of individual and team performance

When working as a member of a team, individuals must make decisions concerning the allocation of resources (e.g., effort) toward individual goals and team goals. As a result, individual and team goals, and feedback related to progress toward these goals, should be potent levers for affecting resource allocation decisions. This research develops a multilevel, multiple-goal model of individual and team regulatory processes that affect the allocation of resources across individual and team goals resulting in individual and team performance. On the basis of this model, predictions concerning the impact of individual and team performance feedback are examined empirically to evaluate the model and to understand the influence of feedback on regulatory processes and resource allocation. Two hundred thirty-seven participants were randomly formed into 79 teams of 3 that performed a simulated radar task that required teamwork. Results support the model and the predicted role of feedback in affecting the allocation of resources when individuals strive to accomplish both individual and team goals.     

Identification of tone duration, line length, and letter position: an experimental approach to timing and working memory deficits in schizophrenia

Patients with schizophrenia display numerous cognitive deficits, including problems in working memory, time estimation, and absolute identification of stimuli. Research in these fields has traditionally been conducted independently. We examined these cognitive processes using tasks that are structurally similar and that yield rich error data. Relative to healthy control participants (n = 20), patients with schizophrenia (n = 20) were impaired on a duration identification task and a probed-recall memory task but not on a line-length identification task. These findings do not support the notion of a global impairment in absolute identification in schizophrenia. However, the authors suggest that some aspect of temporal information processing is indeed disturbed in schizophrenia.     

An emerging postural response: is control of the hip possible in the newly walking child?

Previous researchers have proposed that because of their slow muscle-response latencies, 1- to 2-year-old children are unable to control hip-dominant postural responses when responding to balance threats (G. McCollum & T. Leen, 1989). To test that proposition, the authors exposed 41 children to backward support-surface translations and recorded muscle activations and movement kinematics. Children between 10 months and 10 years of age stood on a platform that was unexpectedly moved. Passive hip-dominant responses were observed among the least experienced walkers. In contrast, older children produced an active response, signified by higher levels of abdominal and quadriceps muscle activity and accompanied by larger hip flexor torques. Greater success in withstanding large magnitudes of perturbations were associated with actively generated hip responses.     

Hand movements deviate toward distracters in the absence of response competition

In a series of experiments, participants reached to targets in the presence of visual distracters that were either adjacent to the target or located along the reach path. The reaching movements were affected by the presence of the distracters, with the movement paths deviating toward the distracters. Those deviations were observed under two different conditions: (a) one in which the distracter could potentially have been a movement target; and (b) another in which the distracter never was a possible target. Because the movement was affected by the distracter in both situations, the results suggested that response competition is not necessary for distracter-induced reach-path deviations. Instead, the authors propose that attention to a distracter is sufficient to affect the to-target movement. The movement deviations may reveal an effective mechanism for coping with stimulus-rich environments.