Dark-adaptation of the human rod system: A new hypothesis

Following a long, full bleach, rod dark-adaptation curves from two normal trichromats were obtained with test fields of various size, exposure time and retinal eccentricity. The results show that there is a substantial region of threshold recovery with an approximately constant, linear slope of about 0.27 log per minute of dark-adaptation, which is independent of the test variables. It is suggested that the increase in sensitivity during this constant, linear slope is completely determined by changes in the concentration of bleached rhodopsin. The relationship between change of relative threshold (T) and fraction of bleached rhodopsin ( B ) is given by T=B ^3,7. This exponential law is well described by the displacement of the equilibrium between the active and inactive states of an allosteric enzyme built as a tetrarner.     

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.     

Decomposing coronary-prone behavior: Dimensions of type a behavior in the Videotaped Structured Interview

This study examined the factorial structure of data generated in the Videotaped Structured Interview for assessment of Type A behavior. Based on the literature, it was argued that there are at least three distinct concepts of Type A behavior, focused on competitiveness and pressured drive, speech characteristics, and hostility, respectively. These three concepts were clearly represented among the factors from factor analyses based on data from 282 subjects. Three factors represented speech and psychomotor characteristics, where the first reflected interactions between subject and interviewer (e.g., response latency, interruptions), the second tempo of speech (accelerating, dysrhythmic and rapid speech), and the third oral gestures (e.g., expiratory sighs). Hostility was reflected in two factors, one defined by emotional intensity (e.g., anger when recalling paat event) and the other hostility expressed towards the interviewer. Pressured drive dominated a content factor reflecting self-awareness of Type A behavior. Finally, there was one factor related to psychomotor tension. Through further factor and item analyses, it was possible to combine these factors into three homogeneous and moderately intercorrelated subscales of Type A behavior reflecting Hostility, Speech Characteristics, and Self-Awareness of Type A behavior. These scales showed good interrater agreement and stability over two years. The Self-Awareness Scale was highly correlated with self-report measures of Type A behavior. The Hostility Scale, on the other hand, was moderately related to measures of Type A behavior, anger and hostility, but was unrelated to anxiety. The Speech Characteristic Scale, finally, was virtually unrelated to psychometric measures.     

The factor structure of the Maslach Burnout Inventory in two Swedish human service organizations

The Maslach Burnout Inventory, MBI, is a well established measure of burnout. Its validity outside the USA is, however, uncertain. The aim of the present study was therefore to apply the MBI on personnel in two Swedish human service organizations, comparing factor solutions and scoring norms to the original results. The population consisted of 5730 employees in the Social Insurance Organization (SIO) and the Individual and Family Care section (IFC) of the social welfare agencies. Principal components analysis, principal axes and alpha factor analyses were performed, all with varimax rotation. The suggested three factor solution showed to be remarkably stable irrespective of type of analysis. Score levels were somewhat lower on two subscales in the Swedish population. The conclusion is that the psychometric properties of the MBI seem to be very satisfactory and stable, at least in comparison between Sweden and USA. It is suggested that the dimensionality of MBI is rather invariant, but that the score levels covary with national, cultural, or professional contexts within the human services.     

Therapeutic factors in interactional inpatient groups: Results from a Turkish sample

Therapeutic factors in an inpatient group from Turkey are presented. A total of 40 patients were seen over a period of 2 years and each patient was given Yalom's (1983) 60-item therapeutic factor list on discharge. The first four most valued therapeutic factor groups were Catharsis, Existential Factors, Cohesiveness and Hope. There were significant differences in the highly valued factors in different diagnostic groups. Patients with diagnoses of anxiety/somatization and borderline/identity problem preferred factors resembling those in many out-patient studies. The results are discussed in the light of relevant literature.     

Action and emotion in everyday life

This study of naturally occurring behaviour employed a "beeper technique" to investigate the actions carried out by 152 subjects in eight different groups, viz. adult students, employed students who were also parents, unemployed, art students, doctoral students, alcoholics, retired people and a control group. Actions were sampled for seven subsequent days, five times per day between 8 a.m. and 10 p.m. at randomly selected occasions. Each action was rated on a number of variables, shortly after it was sampled (median delay approximately 10 min). Some of the findings were: Time allocation corresponded well with national estimates. Being under situational control was highly aversive. Instrumental and consummatory orientations correlated positively. The background variables were, on the whole, only rather weakly related to action ratings, but it was found that women and retired persons tended to report a higher level of well-being.     

Research as a family therapy intervention technique

The utilization of the research process as an intervention has recently been described in the family therapy literature. However, it is important to draw a distinction between research as intervention and research as a unique family therapy intervention technique. From a family systems perspective, research as an intervention technique may make therapy more palatable for some families. A case study is presented in which this technique created the context for change for a family involved in a chronic illness research project.The author would like to thank Dr. Wendy L. Watson for her participation as a member of the clinical team and Drs. Fabie Duhamel and Wendy L. Watson for their helpful critiques on earlier drafts of this paper.Supported by a grant from the Albert Foundation for Nursing Research.     

Individual response patterns and the effects of different behavioral methods in the treatment of claustrophobia

The importance of individual response patterns in claustrophobic patients was examined in the present study. Thirty-four psychiatric outpatients with a phobia of enclosed spaces were assessed in a small test chamber. During the test their overt behavior was video-taped, heart-rate was measured continuously, and self-ratings of experienced anxiety were made at certain intervals. On the basis of their reactions in the test situation, the patients were divided into two groups showing different response patterns—behavioral and physiological reactors. Within each group the patients were randomly assigned to one behaviorally-focused method (exposure), one physiologically-focused method (applied relaxation) and a waiting-list control group. The patients were treated individually in eight sessions. The between-group comparisons showed that both exposure and applied relaxation were significantly better than the waiting-list condition. Furthermore, exposure yielded better results than applied relaxation for the behavioral reactors, while applied relaxation was better than exposure for the physiological reactors. The improvements were maintained at a follow-up assessment 14 months after the end of treatment. The results support the hypothesis that greater effects are achieved when the method used fits the patient's response pattern than when it does not.     

Scotopic contrast hues displaced toward blue

Abstract.— Pre-stimulation with a neutral white light, in a dark-adapted state, produced a disposition for a scotopic hue of violet of about 463 nm. The observation may be explained on the basis of Helmholtz's theory of complementary negative afterimages, provided that (1) the assumption that neutral white is observed when the three types of cone receptors are activated to about the same degree, is rejected, and (2) the origin of the scotopic contrast hues is assumed to be located centrally to the photochemical systems of the receptors.     

The effect of stimulus preexposure upon the context effect in taste-aversion learning in noradrenaline-depleted rats

The present investigation was designed to study the effect of preexposure to a saccharin plus noisy bottle stimulus compound, or to each element by itself, upon the extinction-dependent "context effects" (due to the presencelabsence of the noisy bottle contextual cue) in taste-aversion learning, following noradrenaline (NA) depletion via a single systemic DSP4 injection. Since contextual manipulations have provided a reliable means of studying selective attentional processes the current theorising on the role of noradrenaline can be effectively accommodated. It was found that, under the No Preexposure and Noisy Bottle Preexposure conditions, the "context effect" during the saccharin preference tests, after reinstatement of the noisy bottles for all groups, was totally absent for the NA-depleted rats; in the Saccharin plus Noisy Bottle Preexposure condition the "context effect" was partially blocked for the NA depleted rats and in the Saccharin Preexposure condition it was at least as strong as in the control condition, These findings may be interpreted as supporting our conclusions, concerning NA-depleted rats derived from several different investigations, i.e. that following NA loss rats fail to attend sufficiently to contextual cues in taste-neophobia and taste-aversion situations. Thus, the attentional deficit may be described as an inability to attend to all aspects of the taste stimulus plus exteroceptive context stimulus compound. Although the selective attentional hypothesis of noradrenaline function requires a good deal of alteration, it remains the most parsimonious account that can be described at present.