Induced self-motion in central vision

Previous research on visually induced self-motion found that stimulation of the central visual field (up to 30 degrees in diameter) results in perceived object motion while self-motion requires peripheral stimulation. In the present study, perceived self-motion was induced with a radially expanding pattern simulating observer motion through a space filled with dots, with visual angles of 7.5 degrees, 10.6 degrees, 15 degrees, and 21.2 degrees. Speed and texture density were also varied. The duration of reported self-motion (a) decreased with increased speed, (b) failed to increase with increased visual angle, and (c) decreased with visual angle at the highest speed level. In a second experiment, subjects rated the perceived depth of the displays. The speed and speed/area interaction effects on judged depth matched those found for induced self-motion. These results suggest an extension of the focal/ambient theory: In addition to a more primitive ambient processing mode that requires peripheral vision, there is a higher level system concerned with ambient processing that functions in the central visual field and uses more complex stimulus information, such as internal depth represented in a radially expanding pattern.     

Possible participation of D3 and D4 dopaminergic receptors on genital reflexes induced by cocaine in paradoxical sleep deprived male rats

Previous studies have demonstrated that paradoxical sleep deprivation (PSD) potentiates cocaine-induced genital reflexes in male rats and both D1 and D2 receptors may play a role in those effects, and to examine the possibility that such might involve other dopaminergic receptors, we investigated the effects of D3 and D4 receptor subtype antagonists on cocaine-induced reflexes in sleep-deprived rats. Separate groups of PSD rats received saline, D3 (U9919A; 0.75, 1.5 and 3 mg/kg) or D4 (L745870; 0.75, 1.5 and 3 mg/kg) antagonists prior to acute cocaine challenge. Results demonstrated that U9919A induced significant reduction in the number of animals that displayed erection and the frequency of erection at two smaller doses, while no significant difference was reported for the D4 receptor antagonist. Although our studies indicate that there is a relevant participation of D3 receptors in male sexual function, D4 receptors seem not to exert an essential role in this model.     

When fit indices and residuals are incompatible

Standard chi-square-based fit indices for factor analysis and related models have a little known property: They are more sensitive to misfit when unique variances are small than when they are large. Consequently, very small correlation residuals indicating excellent fit can be accompanied by indications of bad fit by the fit indices when unique variances are small. An empirical example of this incompatibility between residuals and fit indices is provided. For illustrative purposes, an artificial example is provided that yields exactly the same correlation residuals as the empirical example but has larger unique variances. For this example, the fit indices indicate excellent fit. A theoretical explanation for this phenomenon is provided using relationships between unique variances and eigenvalues of the fitted correlation matrix.     

Childhood Abuse Types and Physical Health at the Age of 24: Testing Health Risk Behaviors and Psychological Distress as Mediators

This study examines whether adult psychological distress and health risk behaviors mediate the relationship between childhood abuse and physical health in adulthood. A randomly selected population-based sample, with oversampling to include a one-third subgroup of former child protection cases, completed a structured interview. Questions pertained to childhood exposure to abuse, adult psychological distress, physical health, and health risk behaviors. Previous research using this sample had identified three abuse typologies: emotional abuse, sexual abuse, and polyvictimization (physical abuse, emotional abuse, and neglect). All three typologies were significantly associated with poorer self-reported physical health. Psychological distress and health risk behaviors partially mediated the relationship between nonabuse, sexual abuse, polyvictimization, and physical health, and fully mediated the relationship between emotional abuse and physical health. The results of this study indicate that health risk behaviors and symptoms of psychological distress could contribute to some of the long-lasting consequences of childhood abuse on adult physical health.     

Development through interruptions and reparations – A case study of a dual challenging psychotherapy

The aim of this study was to understand how relational difficulties in psychotherapy may be handled to represent possibilities for change. Temporary interruptions and subsequent reestablishment of contact were chosen as the strategic focus in one severely challenging case of long term psychodynamic psychotherapy where outcome was known to be good. Interruptions and reestablishments were conceptualised by how the informants gave meaning to them. The choice of focus represented a strategic selection of events in the course of therapy where the regulation of the alliance by the therapist as well as by the patient was at stake. A detailed case record was studied and interviews with patient and therapist were conducted. A hermeneutical-phenomenological approach was used to analyse the material. The narrative dimension was important in structuring and interpreting the data. It was shown how important relational difficulties, such as mutual incompatible expectations and demands was handled both on a structural and interpersonal level, and some important steps and hallmarks of the healing process was identified. Close inspection of the course of events in psychotherapies is seen as a promising method for bringing a better understanding of how change processes unfold.     

The effect of exposure duration on visual character identification in single, whole, and partial report

The psychometric function of single-letter identification is typically described as a function of stimulus intensity. However, the effect of stimulus exposure duration on letter identification remains poorly described. This is surprising because the effect of exposure duration has played a central role in modeling performance in whole and partial report (Shibuya & Bundesen, 1988). Therefore, we experimentally investigated visual letter identification as a function of exposure duration. We compared the exponential, the gamma, and the Weibull psychometric functions, all with a temporal offset included, as well as the ex-Gaussian, the log-logistic, and finally the squared-logistic, which is a psychometric function that to our knowledge has not been described before. The log-logistic and the squared-logistic psychometric function fit well to experimental data. Also, we conducted an experiment to test the ability of the psychometric functions to fit single-letter identification data, at different stimulus contrast levels; also here the same psychometric functions prevailed. Finally, after insertion into Bundesen's Theory of Visual Attention (Bundesen, 1990), the same psychometric functions enable closer fits to data from a previous whole and partial report experiment.