Languages for Gestalts of line patterns

Any formal model of visual Gestalt perception requires a language for representing possible perceptual structures of visual stimuli, as well as a decision criterion that selects the actually perceived structure of a stimulus among its possible alternatives. This paper discusses an existing model of visual Gestalt perception that is based on Structural Information Theory. We investigate two factors that determine the representational power of this model: the domain of visual stimuli that can be analyzed, and the class of perceptual structures that can be generated for these stimuli. We show that the representational power of the existing model of Structural Information Theory is limited, and that some of the generated structures are perceptually inadequate. We argue that these limitations do not imply the implausibility of the underlying ideas of Structural Information Theory and introduce alternative models based on the same ideas. For each of these models, the domain of visual stimuli that can be analyzed properly is formally defined. We show that the models are conservative modifications of the original model of Structural Information Theory: for cases that are adequately analyzed in the original model of Structural Information Theory, they yield the same results.     

Neurocognitive outcomes following pediatric brain injury: A developmental approach

Developmental neuropsychologists postulate that “immaturity” of the cerebral cortex should no longer be perceived as a protective factor. They argue that injury to the young brain may affect new learning by disrupting the skills in the midst of being acquired and skills that are yet to be developed. Cognitive deficits or weaknesses that are not detectable in the acute phase following a traumatic brain injury (TBI) may emerge over development as more complex skills are needed, thereby creating a developmental lag between children who sustained a pediatric TBI and typical age peers. This literature review was conducted to evaluate the developmental perspective on neurocognitive recovery/development following a TBI. Overall, the described findings support a developmental view and suggest that predictions of prognosis should be based on the child's remaining ability to learn.     

An organizing model for recent cognitive science work on the self

An organizing model of ‘the self’ emerges from applying various kinds of brain injury to recent cognitive science and philosophical work on ‘the self’. This model unifies various contents and mechanisms central to current notions of the self. The article then highlights several criteria and aspects of this notion of self. Qualities of the right type and level of psychological significance delineate ‘the self’ as an organizing concept useful for recent philosophical work and cognitive science research.     

Survival from the Brain's Perspective

The concern about man's harmful impact on the environment focuses attention on the external environment, i.e., the real world out there, which may not survive in a form to support life. But supporting life of an individual is in the hands of that individual's brain, which is primarily concerned with various needs of the internal environment, also referred to as the self. Confronted with diverse and often competing needs, the brain has evolved a complexity in man, which makes it doubtful that any one collective strategy may be effective in preserving the external environment.     

Site preference and alloying effect of tungsten in the μ phase of Co7Mo6

The electronic structures of the μ phase of Co₇Mo₆ were investigated by means of first-principles calculation based on the density functional theory. The calculated equilibrium lattice parameters of Co₇Mo₆ are in good agreement with the experimental results. The results of calculation reveal that the addition of tungsten (W) promotes the stability of the μ phase of Co₇Mo₆ and W tends to participate in its formation. Through analysing the calculated electronic structure (partial density of states and charge density difference), it can be noted that a strong interaction exists due to d–d hybridization. Also, the majority of the atoms may contribute their valence electrons to the formation of metallic bonds in binary and ternary systems. Furthermore, the calculated results show that the doped W atom prefers to occupy the Co site in Co₇Mo₆ μ phase.     

Dynamic testing of learning potential in adults with cognitive impairments: A systematic review of methodology and predictive value

Dynamic testing includes procedures that examine the effects of brief training on test performance where pre‐ to post‐training change reflects patients’ learning potential. The objective of this systematic review was to provide clinicians and researchers insight into the concept and methodology of dynamic testing and to explore its predictive validity in adult patients with cognitive impairments. The following electronic databases were searched: PubMed, PsychINFO, and Embase/Medline. Of 1141 potentially relevant articles, 24 studies met the inclusion criteria. The mean methodological quality score was 4.6 of 8. Eleven different dynamic tests were used. The majority of studies used dynamic versions of the Wisconsin Card Sorting Test. The training mostly consisted of a combination of performance feedback, reinforcement, expanded instruction, or strategy training. Learning potential was quantified using numerical (post‐test score, difference score, gain score, regression residuals) and categorical (groups) indices. In five of six longitudinal studies, learning potential significantly predicted rehabilitation outcome. Three of four studies supported the added value of dynamic testing over conventional testing in predicting rehabilitation outcome. This review provides preliminary support that dynamic tests can provide a valuable addition to conventional tests to assess patients’ abilities. Although promising, there was a large variability in methods used for dynamic testing and, therefore, it remains unclear which dynamic testing methods are most appropriate for patients with cognitive impairments. More research is warranted to further evaluate and refine dynamic testing methodology and to further elucidate its predictive validity concerning rehabilitation outcomes relative to other cognitive and functional status indices.     

Robust mean and covariance structure analysis through iteratively reweighted least squares

Robust schemes in regression are adapted to mean and covariance structure analysis, providing an iteratively reweighted least squares approach to robust structural equation modeling. Each case is properly weighted according to its distance, based on first and second order moments, from the structural model. A simple weighting function is adopted because of its flexibility with changing dimensions. The weight matrix is obtained from an adaptive way of using residuals. Test statistic and standard error estimators are given, based on iteratively reweighted least squares. The method reduces to a standard distribution-free methodology if all cases are equally weighted. Examples demonstrate the value of the robust procedure.The authors acknowledge the constructive comments of three referees and the Editor that lead to an improved version of the paper. This work was supported by National Institute on Drug Abuse Grants DA01070 and DA00017 and by the University of North Texas Faculty Research Grant Program.     

Relationships between factors of intelligence and brain volume

The recent explosion of studies aimed at determining the biological basis of intelligence has revealed that cognitive ability has a strong biological substrate. This study expands on this literature by examining the relation between cognitive ability and MRI-measured brain volume and head size in a sample of adult male siblings recruited from the London, Ontario community in Canada. It was found that brain volume correlated with IQ at 0.35 (P<0.01), thus replicating the results of past studies. Corrections for restriction of range and attenuation in both this and past studies suggest that the population value of the brain volume-IQ correlation is closer to 0.50. Head size variables, with one exception, also showed the expected positive correlations with IQ. The results of a vector analysis on factor scores indicated that the more highly g-loaded a test was the more highly it correlated with brain volume (r=0.59, P<0.01). The sum of the data suggested that although brain volume (and to a lesser extent, head size) is predictive of g, fluid ability, and memory, it does not predict crystallized ability. Unexpectedly, the higher the spatial imaging loading of a test, the less its correlation with brain volume (vector correlation=−0.84, P<0.001).