How owls structure visual information

Recent studies on perceptual organization in humans claim that the ability to represent a visual scene as a set of coherent surfaces is of central importance for visual cognition. We examined whether this surface representation hypothesis generalizes to a non-mammalian species, the barn owl (Tyto alba). Discrimination transfer combined with random-dot stimuli provided the appropriate means for a series of two behavioural experiments with the specific aims of (1) obtaining psychophysical measurements of figure–ground segmentation in the owl, and (2) determining the nature of the information involved. In experiment 1, two owls were trained to indicate the presence or absence of a central planar surface (figure) among a larger region of random dots (ground) based on differences in texture. Without additional training, the owls could make the same discrimination when figure and ground had reversed luminance, or were camouflaged by the use of uniformly textured random-dot stereograms. In the latter case, the figure stands out in depth from the ground when positional differences of the figure in two retinal images are combined (binocular disparity). In experiment 2, two new owls were trained to distinguish three-dimensional objects from holes using random-dot kinematograms. These birds could make the same discrimination when information on surface segmentation was unexpectedly switched from relative motion to half-occlusion. In the latter case, stereograms were used that provide the impression of stratified surfaces to humans by giving unpairable image features to the eyes. The ability to use image features such as texture, binocular disparity, relative motion, and half-occlusion interchangeably to determine figure–ground relationships suggests that in owls, as in humans, the structuring of the visual scene critically depends on how indirect image information (depth order, occlusion contours) is allocated between different surfaces. Electronic Publication     

Preliminary examination of sex differences in depressive symptoms among adolescent psychiatric inpatients: the role of anxious symptoms and generalized negative affect.

Assessed the emerging view that generalized negative affect and anxious symptoms are important in understanding sex differences in depressive symptoms. Sixty-three adolescent psychiatric inpatients (32 boys, 31 girls), ages 12 to 16 (M = 13.87, SD = 1.36), completed measures of positive and negative affect and anxious and depressive symptoms. Results demonstrated, as predicted, that depressive and anxious symptoms were more highly associated in adolescent girls than boys. Furthermore, girls with depressive symptoms were more likely to have comorbid anxious symptoms than boys with depressive symptoms. Sex differences were not found for adolescents with specific depressive symptoms and specific anxious symptoms (i.e., the absence of comorbidity). Our findings supported the possibility that sex differences in pure forms of depression are overestimated and that comorbid internalizing conditions may be more prevalent in adolescent girls than boys.     

Misadventures In Conditional Expectation: The Two-Envelope Problem

Several fallacies of conditionalization are illustrated, using the two-envelope problem as a case in point This revised version was published online in July 2006 with corrections to the Cover Date.     

Facial expression recognition ability among women with borderline personality disorder: implications for emotion regulation?

This study examined recognition of facial expressions of emotion among women diagnosed with borderline personality disorder (BPD; n = 21), compared to a group of women with histories of childhood sexual abuse with no current or prior diagnosis of BPD (n = 21) and a group of women with no history of sexual abuse or BPD (n = 20). Facial recognition was assessed by a slide set developed by Ekman and Matsumoto (Japanese and Caucasian Facial Expressions of Emotion and Neutral Faces, 1992), expanded and improved from previous slide sets, and utilized a coding system that allowed for free responses rather than the more typical fixed-response format. Results indicated that borderline individuals were primarily accurate perceivers of others' emotions and showed a tendency toward heightened sensitivity on recognition of fear, specifically. Results are discussed in terms of emotional appraisal ability and emotion dysregulation among individuals with BPD.     

Convergent cortical representation of semantic processing in bilinguals

This study examined whether semantic processes in two languages (English and Spanish) are mediated by a common neural system in fluent bilinguals who acquired their second language years after acquiring their first language. Functional magnetic resonance imaging was performed while bilingual participants made semantic and nonsemantic decisions about words in Spanish and English. There was greater activation for semantic relative to nonsemantic decisions in left and right frontal regions, with greater left frontal activation. The locations of activations were similar for both languages, and no differences were found when semantic decisions for English and Spanish words were compared directly. These results demonstrate a shared frontal lobe system for semantic analysis of the languages and are consistent with cognitive research on bilingualism indicating that the two languages of a bilingual person access a common semantic system.     

Pattern of Neuropsychological Deficit at Age Five Years Following Neonatal Unilateral Brain Injury

The pattern of language deficit following left-hemisphere brain injury and visual/spatial deficit following right-hemisphere injury in an adult or older child is well recognized, but has been inconsistently reported following presumed neonatal brain injury. Our prospective study of 24 children at age 5 with documented neonatal unilateral brain injury lends support to the theory of hemisphere specialization at the time of birth. Twelve children who had unilateral left-hemisphere lesion were compared to 12 children with unilateral right-hemisphere lesion of similar timing and severity. Relative visual/spatial deficit following right-hemisphere lesion and receptive language deficit following left-hemisphere lesion were identified. Lateralized measures of grip strength, fine motor speed, and fine motor dexterity were not significantly different between the groups for either hand in this nonhemiparetic study sample. Only one child with a left-hemisphere lesion was left-handed, and only one child (right-lesion) had a hemiparesis.     

Results of EMG analysis using the Polish mini-computer ANOPS

During a study tour of the Neurological Clinic in Warsaw, the automatic EMG analysis procedure by means of the Polish computer ANOPS was tested, standard values worked out and their diagnostic information value tested on patients with neuromuscular diseases. To obtain normal values, leads from four muscles of each of 21 healthy persons were made and the electromyograms of each muscle described by five different parameters. For a differentiated neuromuscular diagnosis it is significant that the computer not only calculates the mean values of each EMG parameter but provides histograms from which further statistical indices and diagnostic information can be obtained.     

WAIS test-retest reliability for a clinical out-patient sample.

WAIS test-retest reliabilities were calculated for a clinical out-patient sample with testing intervals varying from 1 to 10 yr. There was no relationship between test-retest interval and the stability of test scores and the correlations between IQs were quite satisfactory (Full Scale IQ = .897, Verbal IQ = .906, Performance IQ = .876). Reliabilities remained high even when the sample was divided by diagnosis into organic, neurotic, personality disorder, and schizophrenic subgroups.     

Relationships between Hand Test variables and mental retardation: a confirmation and extension.

Eighty-one mentally retarded individuals, including a range of deficiencies (severe, moderate, and mild), were given the Hand Test in order to investigate the relationship between IQ and personality. There were significant correlations between Hand Test personality variables and IQ and different subgroup configurations were noted. Implications of the results are discussed.