Prism adaptation while tracking and saccading

It is known that positional discordance between the spatial senses is a sufficient condition for prism adaptation of registered eye-in-head position. In this experiment adaptation was carried out under conditions in which Ss viewed their feet while making extensive tracking or saccading movements of their eyes. It has been claimed that tracking makes available less precise position information than saccading (Festinger and Canon 1965), but it is found that both modes are equally successful in causing this form of adaptation. It is concluded that either tracking and saccading yield equally valid estimates of eye-in-head position, or that the normal straight ahead position of the eye is a unique reference position.     

Pain and pain perception

Pain is both sensual perception and sense of touch, and it leads to emotional change of health, which has an effect back to a pain perception. Experience of pain is modified by intern and extern influences, and it can appear very multiformly in the chronicity. A part of these factors are described.     

Negative affect and sensitization to pain

Pain usually has a strong negative affective component, which is believed to modulate pain perception. After reviewing theories on the link between negative affect and pain, mechanisms are discussed by which negative affect may either increase or inhibit pain. Possible pain-inhibiting mechanisms are endogenous opioid release, blood pressure reactivity, and distraction of attention; possible pain-increasing mechanisms are autonomic and muscular reactivity, misattribution of arousal, hypervigilance to pain, worrying, and avoidance behavior. It is emphasized that each of these mechanisms can be very adaptive in acute pain situations to prevent injury and promote recovery. In chronic pain, however, ongoing physiological arousal and hypervigilance to pain, induced or magnified by negative affect, may cause sensitization to pain. Furthermore, worrying about pain and avoidance of pain-inducing activities may increase negative affect, ypervigilance, and functional disability. It is argued that, in the long run, pain-related negative affect has sensitizing and disabling effects.     

Catastrophizing and pain perception in sport participants

Abstract

Two studies were conducted to examine the relation between catastrophizing and pain in sport participants. Study 1 compared the factor structure of the Pain Catastrophizing Scale (PCS; Sullivan et al., 1995) in a sample of 97 individuals who reported engaging in regular sporting activity and 140 sedentary individuals. Confirmatory factor analysis revealed that, in both sport and sedentary samples, a three factor solution, comprising rumination, magnification, and helplessness provided the best fit to the data. Study 2 examined differences in pain perception in 54 (28 women, 26 men) varsity athletes and 54 (27 women, 27 men) sedentary controls who participated in an experimental pain procedure. Participants completed the PCS prior to immersing one arm in ice water for one minute. Athletes reported less pain than sedentary individuals, and men reported less pain than women. For both athlete and sedentary groups, catastrophizing was a significant predictor of pain experience. Regression analyses revealed that although catastrophizing accounted for differences in pain perception between men and women     

Mechanisms of long-term dark adaptation

It has previously been suggested that long-term dark adaptation is controlled by bleaching signals that regulate the activity of an allosteric, positively cooperative protein (Stabell et al., 1986a, b). Recent biochemical evidence strongly supports this assumption, indicating that the primary regulator of the light-sensitive channels in the plasma membrane of the outer segments of the photoreceptors is a homo-oligomeric, allosteric, positively cooperative protein. In this report, we discuss the possibility that signals from bleached photopigments may control the dark-adaptation process through the allosteric protein of the plasma membrane. It is suggested that the concentrations of the bleached photopigment and of the allosteric effector are reciprocal quantities.     

Neurocognitive aspects of pain perception

The perception of pain is sensitive to various mental processes such as the feelings and beliefs that someone has about pain. It is therefore not exclusively driven by the noxious input. Attentional modulation involving the descending pain modulatory system has been examined extensively in neuroimaging studies. However, the investigation of neural mechanisms underlying more complex cognitive modulation is an emerging field in pain research. Recent findings indicate an engagement of the ventrolateral prefrontal cortex during more complex modulation, leading to a change or reappraisal of the emotional significance of pain. Taking placebo-induced analgesia as an example, we discuss the contribution of attention, expectation and reappraisal as three basic mechanisms that are important for the cognitive modulation of pain.     

Beautiful faces in pain: Biases and accuracy in the perception of pain

Abstract

The impact of appearance-based information on judgments about the psychological functioning of pain patients was investigated. Video-tapes of low back pain patients experiencing pain were used as stimulus materials. Subjects viewed silent video clips and photographs of the patients' faces and made judgments about the functioning of these patients. These judgments were affected both by patient physical attractiveness and gender. Physically attractive patients and male patients were judged to be functioning better than physically unattractive and female patients. The judgments were reasonably described as biased because the perceived differences about patients varying in attractiveness and sex were not associated with measures of actual patient functioning.     

Cognitive mediators of pain perception and tolerance

A social learning model of pain perception and tolerance was evaluated. Responses to cold-pressor pain were examined in 4 groups of 20 Ss each. One group was given instruction in cognitive coping strategies, the 2nd was given a monetary incentive contingent on tolerance time, the 3rd was given both cognitive training and monetary reinforcement, and a no-treatment control group was given neither. Incentive and coping instructions significantly increased tolerance but did not alter pain perception. A path analysis indicated that pain tolerance was affected by self-efficacy, which in turn was predicted by pain expectancy and the provision of incentives. Incentive also had an impact on tolerance that was independent of self-efficacy. Pain perception was strongly affected by pain expectancy, but was unrelated to self-efficacy.     

Changes in motion perception following oculomotor smooth pursuit adaptation

The hypothesis that oculomotor smooth pursuit (SP) adaptation is accompanied by alterations in velocity perception was tested by assessing coherence thresholds, using random-dot kinematograms before and after the adaptation paradigm. The results showed that the sensitivity to coherent motion at 10 deg/sec (the initial target velocity during adaptation) was reduced after the SP adaptation, ending up at a level that was between those normally observed for velocities of 10 and 20 deg/sec. This is consistent with an overestimation of the velocity of the coherent motion and suggests that SP adaptation alters not only the oculomotor output, but also the perception of target velocity.     

Rapid adaptation of the vestibulo-ocular reflex and induced self-motion perception

When a rigid object moves toward the eye, it is usually perceived as being rigid. However, in the case of motion away from the eye, the motion and structure of the object are perceived nonveridically, with the percept tending to reflect the nonrigid transformations that are present in the retinal image. This difference in response to motion to and from the observer was quantified in an experiment using wire-frame computer-generated boxes which moved toward and away from the eye. Two theoretical systems are developed by which uniform three-dimensional velocity can be recovered from an expansion pattern of nonuniform velocity vectors. It is proposed that the human visual system uses two similar systems for processing motion in depth. The mechanism used for motion away from the eye produces perceptual errors because it is not suited to objects with a depth component.     

Target distance and adaptation in distance perception in the constancy of visual direction

Hay and Sawyer recently demonstrated that the constancy of visual direction (CVD) also operates for near targets. A luminous spot in the dark, 40 cm from the eyes, was perceived as stationary when S nodded his head. This implies that CVD takes target distance, as well as head rotation, into account as a stationary environment is perceived during head movements. Distance is a variable in CVD because, during a turning or nodding of the head, the eyes become displaced relative to the main target direction, the line between the target and the rotation axis of the head. This displacement of the eyes during head rotation causes an additional change in the target direction, i.e., a total angular change greater than the angle of the head rotation. The extent of this additional angular displacement is greater the nearer the target. We demonstrated that the natural combination of accommodation and convergence can supply the information needed by the nervous system to compensate for this additional target displacement. We also found that wearing glasses that alter the relation between these oculomotor adjustments and target distance produces an adaptation in CVD. An adaptation period of 1.5 h produced a large adaptation effect. This effect was not entirely accounted for by an adaptation in distance perception. Measurements of the alteration between oculomotor cues and registered distance with two kinds of tests for distance perception yielded effects significantly smaller than the effect measured with the CVD test. We concluded that the wearing of the glasses had also produced an adaptation within CVD.     

PAUSE for assessment: a multi-level long-term care assessment tool

The author of this article noes that as health care improves, paradoxically, long-term care residents become "older and sicker." In response, many facilities now offer a wide range of levels of residential care, from independent living to Hospice care--and all under the same roof. Chaplains in such facilities can play a key part in identifying changes in individual residents' needs over time. Toward this end, the author introduces PAUSE--a one-page questionnaire designed to be completed by the chaplain after a visit with a resident. The items reflect the chaplain's impressions of several key aspects of the resident's well-being from a single interaction. The questionnaire serves several purposes: it documents the fact of a visit; it allows comparison of impressions at different times and by different visitors; and it quickly highlights "red flag" areas of possible concern for interdisciplinary referral, pastoral follow-up, or possible change in level of care. It might also function as a teaching tool for student chaplains.     

Effects of attentional focusing on pain perception

Two experiments were conducted to examine the hypothesized differential effectiveness of two attentional focusing strategies in pain perception. In the first experiment, subjects (72 male college students) rated their levels of pain after being exposed to either low- or high-intensity pressure stimulation for 75 s. Subjects were instructed to use either an external or internal focus of attention during the pain induction. Results revealed that external focusing was more effective for coping than internal focusing across both levels of stimulus intensity. The second experiment was a replication of the first, and featured bolstered internal focusing and stimulus intensity manipulations. Results showed that high-intensity stimulation produced higher pain ratings than did low-intensity stimulation for subjects in the internal focusing conditions, but not for those in the external focusing conditions. The findings support the power of distraction strategies for dealing with short-term pain with a rapid onset. Theoretical implications are discussed.The authors thank Darwyn E. Linder and Daniel M. Landers for their help in development of this research. The authors are also indebted to Sarah Colley, Jona Davis, Nanci Neuberger, and Rebecca Roberts for their assistance in data collection.     

The nature of adaptation in distance perception based on oculomotor cues

In previous work by the senior authors, brief adaptation to glasses that changed the accommodation and convergence with which objects were seen resulted in large alterations in size perception. Here, two further effects of such adaptation are reported: alterations in stereoscopic depth perception and a change when distance is represented by a response of S’s arm. We believe that the three effects are manifestations of one primary effect, an alteration of the relation between accommodation and convergence on the one hand and the distance they represent in the nervous system (registered distance) on the other. This view was supported by the results of two experiments, each of which demonstrated that the alterations in stereoscopic depth perception could be obtained after adaptation periods which had provided no opportunity to use stereoscopic vision, and that the adaptation effect was larger for depth perception than for size perception when it was obtained under the same conditions; the latter finding was expected if both effects resulted from the same change in registered distance. In three of the five experiments here reported, the variety of cues that could represent veridical distance during the adaptation period was limited. In one condition of adaptation, only the pattern of growth of the retinal images of objects that S approached and the kinesthetic cues for S’s locomotion served as cues to veridical distance. In two other conditions S remained immobile. In one of these, only the perspective distortion in the projection of the scene that S viewed mediated veridical distance, and in the other one familiar objects of normal size were successively illuminated in an otherwise totally dark field, conditions from which opportunities to use stereoscopic vision were again absent. After exposure to each of these adaptation conditions, adaptive changes in perceived size and larger ones in perceived stereoscopic depth were obtained. Because we found that familiar size may serve as the sole indicator of veridical distance in an adaptation process, we concluded that it can function as a perceptual as distinguished from an inferential cue to distance.