Shape-from-shading depends on visual, gravitational, and body-orientation cues

The perception of shading-defined form results from an interaction between shading cues and the frames of reference within which those cues are interpreted. In the absence of a clear source of illumination, the definition of 'up' becomes critical to deducing the perceived shape from a particular pattern of shading. In our experiments, twelve subjects adjusted the orientation of a planar disc painted with a linear luminance gradient from one side to the other, until the disc appeared maximally convex-that is, until the luminance gradient induced the maximum perception of a three-dimensional shape. The vision, gravity, and body-orientation cues were altered relative to each other. Visual cues were manipulated by the York Tilted Room facility, and body cues were altered by simply lying on one side. The orientation of the disc that appeared maximally convex varied in a systematic fashion with these manipulations. We present a model in which the direction of perceptual 'up' is determined from the sum of three weighted vectors corresponding to the vision, gravity, and body-orientation cues. The model predicts the perceived direction of 'up', contributes to our understanding of how shape-from-shading is deduced, and also predicts the confidence with which the 'up' direction is perceived.     

A comparative analysis of North American adolescent and adult mass murderers

Thirty adult mass murderers and 34 adolescent mass murderers in North America are compared on both offender and offense variables to delineate similarities and differences. Findings indicate a plethora of psychiatric disturbances and odd/reclusive and acting-out personality traits. Predisposing factors include a fascination with weapons and war among many of the adolescents and the development of a "warrior mentality" in most of the adults. Precipitating factors indicate a major rejection or loss in the hours or days preceding the mass murder. Results are interpreted through the lens of threat assessment for targeted violence (Borum, Fein, Vossekuil, & Bergland 1999), recognizing that a fact-based, dynamic behavioral approach is most useful for mitigating risk of such an extremely low-base-rate violent crime.     

Indirect personality assessment of the violent true believer

The violent true believer is an individual committed to an ideology or belief system which advances homicide and suicide as a legitimate means to further a particular goal. The author explores useful sources of evidence for an indirect personality assessment of such individuals. He illustrates both idiographic and nomothetic approaches to indirect personality assessment through comparative analyses of Timothy McVeigh, an American who bombed the federal building in Oklahoma City in 1995, and Mohamed Atta, an Egyptian who led the airplane attacks against the World Trade Center and the Pentagon in 2001. The risks of indirect personality assessment and ethical concerns are identified.     

Grammatical language impairment and the specificity of cognitive domains: relations between auditory and language abilities

Grammatical-specific language impairment (G-SLI) in children, arguably, provides evidence for the existence of a specialised grammatical sub-system in the brain, necessary for normal language development. Some researchers challenge this, claiming that domain-general, low-level auditory deficits, particular to rapid processing, cause phonological deficits and thereby SLI. We investigate this possibility by testing the auditory discrimination abilities of G-SLI children for speech and non-speech sounds, at varying presentation rates, and controlling for the effects of age and language on performance. For non-speech formant transitions, 69% of the G-SLI children showed normal auditory processing, whereas for the same acoustic information in speech, only 31% did so. For rapidly presented tones, 46% of the G-SLI children performed normally. Auditory performance with speech and non-speech sounds differentiated the G-SLI children from their age-matched controls, whereas speed of processing did not. The G-SLI children evinced no relationship between their auditory and phonological/grammatical abilities. We found no consistent evidence that a deficit in processing rapid acoustic information causes or maintains G-SLI. The findings, from at least those G-SLI children who do not exhibit any auditory deficits, provide further evidence supporting the existence of a primary domain-specific deficit underlying G-SLI.     

Part-whole practice of movement sequences

A 16-element movement sequence was taught under part-whole and whole-practice conditions. Participants (N = 18) produced a right-arm lever movement to sequentially presented target locations. The authors constructed part-whole practice by providing practice on only the 1st 8 elements on the 1st day of practice (100 repetitions of the 8-element sequence) and on all 16 elements on the 2nd day of practice (100 repetitions of the 16-element sequence). The whole-practice group practiced all 16 elements on both days (100 repetitions of the 16-element sequence per day). No differences in sequence structure or in movement duration of the 16-element sequence were noted on the retention test (Day 3). On transfer tests in which the 1st and last 8 elements were tested separately, however, the participants in the part-whole practice group performed more quickly than the participants in the whole-practice group, especially on the last 8 elements. Participants in the whole-practice group appeared to code the sequence so that it was relatively difficult to fully partition it into separate movements. Thus, on the transfer tests, there continued to be residual effects of the 8 elements that did not have to be produced but slowed down the rate of responding for the whole-practice group. That finding was not observed for the part-whole practice group.     

An outcome management program for extending advances in choice research into choice opportunities for supported workers with severe multiple disabilities

We evaluated an outcome management program for increasing choice opportunities provided by 2 job coaches for 5 supported workers with severe multiple disabilities in a community job. The program involved specifying and monitoring behavioral outcomes among workers and staff, training staff, and supportive and corrective feedback. Increased choice provision occurred for both job coaches across a 1-year period. Results indicate how outcome management can help translate advances in choice research into routine practice.     

High familiarity enhances visual change detection for face stimuli

Does high familiarity with a face enable particularly efficient visual processing? In three experiments, we presented briefly and successively two pairs of faces (either famous or recently learned), masking each presentation. Between the first and the second presentations, one face changed, and the task was to locate this change. Performance was significantly better when the change involved a famous face. This superfamiliarity effect was found only for changes occurring in the left visual field and was abolished by inverting the faces. Extended prior study of the recently learned faces did not improve performance with these stimuli. The results suggest that superfamiliarity promotes highly efficient visual processing and may especially activate a configural mode of analysis.     

Conceptual processing effects on automatic memory

In the present study, influences of conceptual processing on automatic forms of memory were investigated, using a category production task. The experiment employed Jacoby's (1991) process dissociation procedure and fits of multinomial models to estimate conscious and automatic memory for semantic and graphemic study tasks. Memory estimates from a generate-source model indicated more automatic memory for semantic than for graphemic items on the category production task. These results provide support for conceptual processing influences on automatic forms of memory.