A computational feature binding model of human texture perception

We present a computational model for human texture perception which assigns functional principles to the Gestalt laws of similarity and proximity. Motivated by early vision mechanisms, in the first stage, local texture features are extracted by utilizing multi-scale filtering and nonlinear spatial pooling. In the second stage, features are grouped according to the spatial feature binding model of the competitive layer model (CLM; Wersing et al. 2001). The CLM uses cooperative and competitive interactions in a recurrent network, where binding is expressed by the layer-wise coactivation of feature-representing neurons. The Gestalt law of similarity is expressed by a non-Euclidean distance measure in the abstract feature space with proximity being taken into account by a spatial component. To choose the stimulus dimensions which allow the most salient similarity-based texture segmentation, the feature similarity metrics is reduced to the directions of maximum variance. We show that our combined texture feature extraction and binding model performs segmentation in strong conformity with human perception. The examples range from classical microtextures and Brodatz textures to other classical Gestalt stimuli, which offer a new perspective on the role of texture for more abstract similarity grouping.     

Amygdala and periaqueductal gray lesions only partially attenuate unconditional defensive responses in rats exposed to a cat

Defensive responses to a cat were observed in rats given excitotoxic lesions of the central nucleus of the amygdala (ACe), dorsolateral periaqueductal gray (dlPAG), ventral periaqueductal gray (vPAG), or sham lesions. Rats were placed adjacent to a compartment containing a cat. Sham-lesioned rats avoided the area nearest the cat and preferred the area furthest away from the cat. They also exhibited numerous defensive responses including, climbing, escape from the apparatus, and freezing. Rats with lesions of the ACe reacted like the sham lesioned rats by preferring the area of the apparatus furthest from the cat, however they climbed and escaped significantly less than sham lesioned rats. Avoidance of the area adjacent to the cat was attenuated in rats with lesions of the vPAG. Climbing along the walls of the apparatus was also attenuated in rats with lesions of the vPAG. Escapes from the apparatus were not significantly reduced by lesions of the vPAG and dlPAG. Thus, ACe lesions attenuated climbing and eliminated escapes, but did not impair locomotion of the rat away from the cat.     

The aftereffects of ventriloquism: are they sound-frequency specific?

Exposing different sense modalities (like sight, hearing or touch) to repeated simultaneous but spatially discordant stimulations generally causes recalibration of localization processes in one or both of the involved modalities, which is manifested through aftereffects. These provide opportunities for determining the extent of the changes induced by the exposure. Taking the so-called ventriloquism situation, in which synchronized sounds and light flashes are delivered in different locations, we examine if auditory recalibration produced by exposing tones of one frequency to attraction by discordant light flashes generalizes to different frequencies. Contrary to an earlier report, generalization was obtained across two octaves. This result did not depend on which modality attention was forced on through catch trials during exposure. Implications concerning the functional site of recalibration are briefly discussed.     

Pain coping and social support as predictors of long-term functional disability and pain in early rheumatoid arthritis

Pain-related avoidance factors and social resources, as assessed by pain coping and social support, are supposed to have lasting effects on functional disability and pain in chronic pain disorders. As a follow-up to a prospective study demonstrating short-term effects after one year (Behaviour Research and Therapy, 36, 179-193, 1998), the role of pain coping and social support at the time of diagnosis was investigated in relationship to the long-term course of functional disability and pain after three and five years in 78 patients with rheumatoid arthritis (RA), taking into account personality characteristics of neuroticism and extraversion, clinical status and use of medication. In line with findings at the one-year follow-up, results showed that more passive pain coping predicted functional disability at the three-year, but not the five-year follow-up. In addition, low levels of social support at the time of diagnosis consistently predicted both functional disability and pain at the three and five-year follow-ups. Results indicate that pain coping and social support, assessed very early in the disease process, can affect long-term functional disability and pain in RA, and suggest that early interventions focusing on pain-related avoidance factors and social resources for patients at risk may beneficially influence long-term outcomes in RA.     

Treatment of pharmacotherapy-refractory posttraumatic stress disorder among Cambodian refugees: a pilot study of combination treatment with cognitive-behavior therapy vs sertraline alone

Cambodian refugees with posttraumatic stress disorder (PTSD) represent a cohort in severe need of treatment, but little information is available to guide treatment choices. We selected a sample of pharmacotherapy-refractory individuals to test the efficacy of combination treatment with sertraline and cognitive-behavior therapy (CBT) for treating PTSD. Participants in this pilot study were ten Khmer-speaking women who had been at a mean age of 22-26 years during the Pol Pot period (1975-1979). These patients were randomly assigned to either sertraline alone or combined treatment. We found that combined treatment offered additional benefit in the range of medium to large effect sizes for PTSD and associated symptoms. Our findings indicate that substantial gains can be achieved by adding CBT to pharmacotherapy for PTSD, and that a program of CBT emphasizing information, exposure, and cognitive-restructuring can be successfully modified for Khmer-speaking refugees.     

The use of latent trajectory models in psychopathology research

Despite the recent surge in the development of powerful modeling strategies to test questions about individual differences in stability and change over time, these methods are not currently widely used in psychopathology research. In an attempt to further the dissemination of these new methods, the authors present a pedagogical introduction to the structural equation modeling based latent trajectory model, or LTM. They review several different types of LTMs, discuss matching an optimal LTM to a given question of interest, and highlight several issues that might be particularly salient for research in psychopathology. The authors augment each section with a review of published applications of these methods in psychopathology-related research to demonstrate the implementation and interpretation of LTMs in practice.     

Using video modeling and reinforcement to teach perspective-taking skills to children with autism

We evaluated video modeling and reinforcement for teaching perspective-taking skills to 3 children with autism using a multiple baseline design. Video modeling and reinforcement were effective; however, only 2 children were able to pass an untrained task, indicating limited generalization. The findings suggest that video modeling may be an effective technology for teaching perspective taking if researchers can continue to develop strategies for enhancing the generalization of these new skills.     

Sequential evaluation of behavioral treatments and methylphenidate dosage for children with attention deficit hyperactivity disorder

We used a sequential approach to evaluate the relative and combined effects of different types of behavioral treatments, as well as dosage of methylphenidate (MPH), on the disruptive behavior of 3 students who had been diagnosed with attention deficit hyperactivity disorder. Results showed that individualized behavioral treatments produced decreases in disruptive behavior equivalent to MPH for all 3 participants and demonstrated the need to evaluate behavioral treatments and medication dosage on an individual basis.     

The effects of presession attention on problem behavior maintained by different reinforcers

The effect of presession attention on the later occurrence of problem behavior was examined with elementary-school children with a range of disabilities. Results of analogue functional analyses suggested an escape function, an attention function, or both. Following the analogue functional analyses, the effects of two antecedent conditions (10-min ignore vs. 10-min attention) were compared on problem behavior in subsequent test conditions. For participants who displayed attention-maintained problem behavior, the test condition involved contingent attention for problem behavior. For participants who displayed escape-maintained problem behavior, the test condition involved contingent escape for problem behavior. Results indicated that participants who displayed attention-maintained problem behavior displayed less problem behavior following presession exposure to attention than when ignored. No such effect was found for presession attention on escape-maintained problem behavior. We discuss matching antecedent-based interventions to the results of functional analysis.     

Measuring the multidimensional self-concept and global self-worth of 6- to 8-year-olds

A downward extension of a Dutch version of Harter's Self-Perception Profile for Children (SPPC) was tested in a Flemish sample of 880 1st to 3rd graders (Mage = 7.18 years, SD = 0.80). In 2nd and 3rd graders, 5 SPPC factors were identified; in 1st graders only 4 were identified. Support was found for the equivalence of structure and measurement for 2nd and 3rd grades and for boys and girls. Most scales possessed reasonable to good internal consistency for these groups. The results support the multidimensionality of self-concept responses for young children and the improving of the distinctiveness of SPPC factors with age. Young children seem to have an ability to verbalize concepts of their global self-worth that can be tapped by self-report measures.