The perception of continuous curves in dot stimuli

Two categorisation experiments are reported in which the perceptual phenomenon that some simple arrays of discrete dots appear as a continuous curve whereas others are perceived as an angular contour or as consisting of separate groups of dots was investigated. Triplets of dots were presented in the first experiment, and complete or incomplete regular dot polygons (ie dots positioned on the vertices of imaginary regular polygons) in the second. In both experiments the perception of a curve versus an angle was determined mainly by the relative orientations of the dots, ie by the angles between successive virtual lines, whereas the lengths of the virtual lines had relatively little influence. In experiment 2 the number of displayed dots was shown to be a second independent factor for perceiving continuity. These results are in agreement with results from experiments on dipole textures discrimination, and suggest the psychological existence and importance of virtual lines in the visual processing of dot stimuli.     

Inhibition of the LH Surge by Restraint Stress in Cyclic Rats: Studies on the Role of GABAA and GABAB Receptors

There is evidence that stress can alter the activity in the brain of gamma-aminobutyricacid (GABA), a neurotransmitter that has been implicated in the regulation of LH secretion. In the present study the role of GABA in the restraint stress-induced inhibition of the LH surge was investigated in the intact cyclic rat. Intracerebroventricular (icv) administration of the GABAA receptor agonist muscimol (0.1, 0.5 or 1 μg) 5 min before the presumed onset of the pro-oestrous LH surge (at 0900 h) caused a dose dependent suppression of the surge. A single dose of the GABAB receptor agonist baclofen (1 μg; icv) injected at 0855 h postponed the onset of the LH surge, and repeated injections at 0855 and 1130 h suppressed the surge. These data indicate that GABA-ergic activity in the brain can inhibit the LH surge in the cyclic rat via GABAA and GABAB receptors. Pro-oestrous rats were subjected to 5 hrs of restraint starting at 0855 h. Pretreatment with the GABAA receptor antagonist bicuculine (1 μg; icv) at 0840, 0940 and 1040 h or pretreatment with the GABAB receptor antagonist phaclofen (10 μg; icv) at 0840 h were ineffective in preventing the restraint-induced inhibition of the LH surge. The results suggest that GABAA and GABAB receptors are not involved in the inhibitory effect of restraint stress on the LH surge.     

Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Active-imaginal exposure: examination of a new behavioral treatment for cynophobia (dog phobia)

The aims of this study were to investigate exposure-based treatments for cynophobia (dog phobia) and to test a newly developed hybrid imaginal exposure treatment that we have named active imaginal exposure. The treatment introduces an in vivo coping component to imaginal exposure whereby the patient physically performs coping responses to an imagined feared stimulus. Eighty-two participants meeting DSM-IV criteria for specific phobia (animal subtype) were randomly assigned to one of three 30-min. treatments: (a) active-imaginal exposure (AI), (b) imaginal exposure alone (IE), or (c) graduated in vivo exposure (IV). Participants completed a behavioral approach test at pre, post, and four-week follow-up. Significant pre- to posttreatment improvement was observed in all three treatment conditions. Response rates at posttreatment were 51.9, 62.1, and 73.1% for the IE, AI, and IV groups respectively. Likewise, effect sizes at posttreatment were 0.76, 1.41, and 1.55 for the IE, AI, and IV groups respectively. Although in the predicted direction, the between group differences were not significant. A similar pattern of results was observed at follow-up. Further, safety behavior utilization during treatment was associated with less improvement--particularly in the two imaginal treatment conditions. Exposure treatments of dog phobia appear feasible and effective in reducing phobic fear and avoidance associated with dog phobia. Furthermore, preliminary evidence suggests that our active-imaginal exposure treatment may be a viable alternative to in vivo exposure.     

The appraisal basis of anger: specificity, necessity and sufficiency of components

The nature of the association between anger and 5 appraisal-action tendency components--goal obstacle, other accountability, unfairness, control, and antagonism--was examined in terms of specificity, necessity, and sufficiency. In 2 studies, participants described recently experienced unpleasant situations in which 1 of the appraisal-action tendency components was present or absent and indicated which emotions they had experienced. The results showed that (a) other accountability and arrogant entitlement, as an instance of unfairness, are specific appraisals ability for anger; and most important, (b) none of the components is necessary or sufficient for anger. The findings suggest that the relation between emotions and appraisal-action tendency components should be conceptualized instead as a contingent association, meaning that they usually co-occur.     

Use of interreflection and shadow for surface contact

The interaction of light with surfaces results in a number of lighting effects that may serve as valuable visual cues. Previous research on shadows has shown them to be effective in determining the three-dimensional (3-D) layout of a scene, but interreflections have been ignored as cues for spatial layout. Interreflections as well as shadows may help to disambiguate the 3-D layout of objects by providing information about an object's contact with a surface. We generated computer images of a box on an extended textured ground plane that was either in contact with the ground or was slightly above the ground. Images were rendered for four conditions: (1) no shadow + no interreflection, (2) shadow only, (3) interreflection only, and (4) shadow + interreflection. A photometrically incorrect condition was also included. The participants rated the degree of contact for each image on a scale, which was used to generate receiver operating characteristic (ROC) curves and a measure of sensitivity. In the images with no shadows or interreflections, the participants performed at chance levels. Interreflections, shadows, and a combination of interreflections and shadows all resulted in high sensitivity for judging object contact. More important, information from shadows and interreflections can be combined, resulting in near-perfect judgment of surface contact. Interreflections and shadows can be effective cues for object contact.     

Treatment Outcome of 18-Month, Day Hospital Mentalization-Based Treatment (MBT) in Patients with Severe Borderline Personality Disorder in the Netherlands

Psychoanalytically oriented day hospital therapy, later manualized and named mentalization-based treatment (MBT), has proven to be a (cost-) effective treatment for patients with severe borderline personality disorder and a high degree of psychiatric comorbidity (BPD) in the United Kingdom (UK). As to yet it has not been shown whether manualized day hospital MBT would yield similar results when conducted by an independent institute outside the UK. We investigated the applicability and treatment outcome of 18-month, manualized day hospital MBT in the Netherlands by means of a prospective cohort study with 45 Dutch patients with severe BPD and a high degree of comorbid Axis I and Axis II disorders. Outcomes were assessed each six months. Symptom distress, social and interpersonal functioning, and personality pathology and functioning all improved significantly, with effect sizes between 0.7 and 1.7. Suicide attempts, acts of self-harm, and care consumption were also significantly reduced. The results indicate that MBT can effectively be implemented in an independent treatment institute outside the UK. This study also supports the clinical effectiveness of manualized day hospital MBT in patients with severe BPD and a high degree of psychiatric comorbidity.     

Cohort differences in Big Five personality factors over a period of 25 years

The notion of personality traits implies a certain degree of stability in the life span of an individual. But what about generational effects? Are there generational changes in the distribution or structure of personality traits? This article examines cohort changes on the Big Five personality factors Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness to Experience, among first-year psychology students in The Netherlands, ages 18 to 25 years, between 1982 and 2007. Because measurement invariance of a personality test is essential for a sound interpretation of cohort differences in personality, we first assessed measurement invariance with respect to cohort for males and females separately on the Big Five personality factors, as measured by the Dutch instrument Five Personality Factors Test. Results identified 11 (females) and 2 (males) biased items with respect to cohort, out of a total of 70 items. Analyzing the unbiased items, results indicated small linear increases over time in Extraversion, Agreeableness, and Conscientiousness and small linear decreases over time in Neuroticism. No clear patterns were found on the Openness to Experience factor. Secondary analyses on students from 1971 to 2007 of females and males of different ages together revealed linear trends comparable to those in the main analyses among young adults between 1982 onward. The results imply that the broad sociocultural context may affect personality factors.     

Augmenting treatment efficiency in exposure therapy for PTSD: a randomized double-blind placebo-controlled trial of yohimbine HCl

The alpha-2 adrenergic receptor antagonist, yohimbine, can facilitate fear extinction in animals and humans. One potential mechanism is increased noradrenergic activity and associated arousal in the presence of conditioned stimuli. Accordingly, yohimbine might augment prolonged exposure (PE) therapy for posttraumatic stress disorder (PTSD), where heightened exposure-oriented arousal is a theorized driver and empirical predictor of treatment success. A double-blind placebo-controlled randomized trial (NCT 01031979) piloted yohimbine augmentation in 26 males with combat-related PTSD. Participants were given one-time dose of yohimbine or placebo prior to the first imaginal exposure. Subsequently, both arms completed standard PE. The primary outcome was trauma-cued heart-rate reactivity a week after the drug/exposure visit, a highly specified, objective measure sensitive to incremental change. Secondary outcomes included arousal during the drug/exposure visit and slope of distress, PTSD, and depression over the course of PE. Consistent with hypothesis, yohimbine led to higher objective and subjective arousal during the drug/exposure visit and to lower trauma-cued heart-rate reactivity one-week later. One dose of yohimbine also led to greater between-session habituation and more rapid improvement on depression, but not PTSD, over the course of care. Results of this controlled pilot indicate support for continued investigation of yohimbine-augmented exposure therapy for PTSD.     

Psychometric Properties of the Multidimensional Perfectionism Scale of Hewitt in a Dutch-Speaking Sample: Associations With the Big Five Personality Traits

We administered the Dutch Multidimensional Perfectionism Scale of Hewitt and Flett (1991, 2004) in a large student sample (N = 959) and performed a confirmatory factor analysis to test the factorial structure proposed by the original authors. The existence of a method factor referring to the negatively keyed items in the questionnaire was investigated by including it in the tested models. Next, we investigated how the 3 perfectionism dimensions are associated with the Five-factor model (FFM) of personality. The 3-factor structure originally observed by the authors was confirmed, at least when a method factor that refers to the negatively keyed items was included in the model. Self-oriented and socially prescribed perfectionism were both distinguished by low extraversion and low emotional stability. Self-oriented perfectionism's positive relationship with both conscientiousness and openness to experience differentiated the 2 perfectionism dimensions from each other. Other-oriented perfectionism was not well-characterized by the Big Five personality traits.