A comparison of two response time models applied to perceptual matching

Two models, a Poisson race model and a diffusion model, are fit to data from a perceptual matching task. In each model, information about the similarity or the difference between two stimuli accumulates toward thresholds for either response. Stimulus variables are assumed to influence the rate at which information accumulates, and response variables are assumed to influence the level of the response thresholds. Three experiments were conducted to assess the performance of each model. In Experiment 1, observers performed under different response deadlines; in Experiment 2, response bias was manipulated by changing the relative frequency ofsame anddifferent stimuli. In Experiment 3, stimulus pairs were presented at three eccentricities: foveal, parafoveal, and peripheral. We examined whether the race and diffusion models could fit the response time and accuracy data through changes only in response parameters (for Experiments 1 and 2) or stimulus parameters (for Experiment 3). Comparisons between the two models suggest that the race model, which has not been studied extensively, can account for perceptual matching data at least as well as the diffusion model. Furthermore, without the constraints on the parameters provided by the experimental conditions, the diffusion and the race models are indistinguishable. This finding emphasizes the importance of fitting models across several conditions and imposing logical psychological constraints on the parameters of models.     

Resolving the debate over birth order, family size, and intelligence

Hundreds of research articles have addressed the relationship between birth order and intelligence. Virtually all have used cross-sectional data, which are fundamentally flawed in the assessment of within-family (including birth order) processes. Although within-family models have been based on patterns in cross-sectional data, a number of equally plausible between-family explanations also exist. Within-family (preferably intact-family) data are prerequisite for separating within- and between-family causal processes. This observation reframes an old issue in a way that can be easily addressed by studying graphical patterns. Sibling data from the National Longitudinal Survey of Youth are evaluated, and the results are compared with those from other studies using within-family data. It appears that although low-IQ parents have been making large families, large families do not make low-IQ children in modern U.S. society. The apparent relation between birth order and intelligence has been a methodological illusion.     

Counterconditioning in the treatment of spider phobia: effects on disgust, fear and valence

From the perspective that disgust is a core feature of spider phobia, we investigated whether the treatment efficacy could be improved by adding a counterconditioning procedure. Women with a clinically diagnosed spider phobia (N = 34) were randomly assigned to the regular one-session exposure condition (EXP) or to the exposure with counterconditioning condition (CC). In the CC-condition tasty food-items were used during the regular exposure exercises and the participants' favourite music was played. Both treatment conditions appeared very effective in reducing avoidance behaviour and self-reported fear of spiders, strongly attenuated the disgusting properties of spiders and altered the affective evaluations in a positive direction. CC was not more effective in altering the affective valence of spiders than EXP and was not superior with respect to the long term treatment efficacy at 1 year follow up. Apparently, regular exposure treatment is already quite effective in altering the affective-evaluative component of spider phobia and it remains to be seen whether it is possible to further improve treatment outcome by means of procedures which are specifically designed to reduce the spiders' negative affective valence.     

Minimal information to determine affine shape equivalence

Participants judged the affine equivalence of 2 simultaneously presented 4-point patterns. Performance level (d') varied between 1.5 and 2.7, depending on the information available for solving the correspondence problem (insufficient in Experiment 1a, superfluous in Experiment 1b, and minimal in Experiments 1c, 2a, 2b) and on the exposure time (unlimited in Experiments 1 and 2a and 500 ms in Experiment 2b), but it did not vary much with the complexity of the affine transformation (rotation and slant in Experiment 1 and same plus tilt in Experiment 2). Performance in Experiment 3 was lower with 3-point patterns than with 4-point patterns, whereas blocking the trials according to the affine transformation parameters had little effect. Determining affine shape equivalence with minimal-information displays is based on a fast assessment of qualitatively or quasi-invariant properties such as convexity/ concavity, parallelism, and collinearity.     

Ratings of emotion in laterally presented faces: sex and handedness effects

Sixteen right-handed participants (8 male and 8 female students) and 16 left-handed participants (8 male and 8 female students) were presented with cartoon faces expressing emotions ranging from extremely positive to extremely negative. A forced-choice paradigm was used in which the participants were asked to rate the faces as either positive or negative. Compared to men, women rated faces more positively, especially in response to right visual field presentations. Women rated neutral and mildly positive faces more positively in the right than in the left visual field, whereas men rated these faces consistently across visual fields. Handedness did not affect the ratings of emotion. The data suggest a positive emotional bias of the left hemisphere in women.     

The Factor Structure of the Beavers Interactional Scales

Confirmatory factor analysis and regression analyses of the Beavers Interactional Scales did not appear to support the model offered by its developers, namely, several specified family attributes contributing respectively to two global factors of Family Competence and Family Style. Moreover, regression analysis indicated that only three of 12 items predicted raters' assessments of Global Family Health, and one of seven items predicted Global Family Style. Individuals interested in the family dynamic centripetal/centrifugal might best think of that as a unitary entity and rate it accordingly.     

Cardiovascular responses to open-field stress in rats: sex differences and effects of gonadal hormones

We studied sex differences in cardiovascular responses to stress using a new radio-telemetry model in which freely-moving Spontaneously Hypertensive rats (SHR) are exposed to open-field novelty stress. This model allowed simultaneous assessment of cardiovascular and behavioural responses to psychological stress. Female SHR in the diestrous stage of their estrous cycle had markedly greater pressor and tachycardic responses to open-field exposure when compared to either female rats not in diestrous or male SHR. Treatment of ovariectomized SHR with estrogen alone had no significant effect on cardiovascular reactivity, while a combined treatment of estrogen and progesterone slightly, but significantly attenuated their pressor response to open-field stress. In addition, treatment of castrated male rats with testosterone significantly enhanced their pressor responses to stress when compared to values obtained before treatment. None of the hormone treatments had any significant effect on heart rate responses to stress. Neither at different stages of the estrous cycle nor after hormone treatments were there any marked changes in behavioural responses in the open-field, making it unlikely that the differences in cardiovascular stress responses were caused by changes in behavioural activity. These data demonstrate differences in cardiovascular stress responses that seem to be dependent on the stage of the estrous cycle. They suggest that particularly androgens, such as testosterone, may enhance pressor responses to stress. On the other hand, a combination of estrogen and progesterone, rather than estrogen alone, may have a small attenuating effect on cardiovascular reactivity.     

Sustained efficacy of dialectical behaviour therapy for borderline personality disorder

Dialectical Behaviour Therapy (DBT) is considered one of the most promising treatments for borderline personality disorder (BPD). Recently, we reported significantly positive effects of 12 months DBT on parasuicidal behaviour and impulsivity in a mixed group of female BPD patients with and without substance abuse. Fifty-eight women with BPD were randomly assigned to either 52 weeks of DBT or treatment as usual (TAU). Follow-up assessment took place at 78 weeks, i.e., 6 months after discontinuation of DBT. Participants were clinical referrals from addiction treatment and psychiatric services. Outcome measures included parasuicidal behaviour, impulsivity and substance abuse. Six months after treatment discontinuation, the benefits of DBT over TAU in terms of lower levels of parasuicidal and impulsive behaviours, and in alcohol use, sustained. No differences between the treatment conditions were found for drug abuse. In conclusion, DBT seems to have a sustained effect on some of the core symptoms of BPD and on alcohol problems in a mixed population of female borderline patients with and without substance abuse problems.     

A psychometric evaluation of the social skills rating system in children with attention deficit hyperactivity disorder

The social skills rating system (SSRS) was developed to assess social skills of children, as observed by multiple raters (teacher, parent, child). Studies of the SSRS have been conducted with handicapped, mentally retarded and learning disabled children. No studies have reported the psychometric properties of the SSRS in a clinical ADHD sample. This is important, because deficient social functioning is associated with ADHD. The present study assesses the psychometric properties of the teacher, parent and child versions of the SSRS in children with ADHD (n = 123), and normal controls (n = 239). Also, the social skills of children with ADHD, as rated on the SSRS were examined. Results support the factor structure and internal consistency of the original SSRS-teacher version. Moreover, support was found for 3 out of 4 scales of the SSRS-parent version. The factor structure of the SSRS-child version could not be replicated. An explanatory factor analysis on the SSRS-child version yielded two factors. Evidence was found for discriminative ability of the SSRS between normal controls and children with ADHD. Finally, informant agreement between raters was found to be poor.