Biomedical subjects

C F Chabris

Publications and source records attributed to C F Chabris.

3 recordsLinked to original sources

PubMed1995

On computational evidence for different types of spatial relations encoding: reply to Cook et al. (1995).

Computational models in psychology play an increasingly important role in characterizing theoretical distinctions, understanding empirical results, and formulating new predictions. However, the proper use of models is subject to debate and interpretation, as Cook, Früh, and Landis (1995) have demonstrated in a critique of neural network simulations reported by Kosslyn, Chabris, Marsolek, and Koenig (1992). These simulation results supported a distinction between two types of spatial relations encoding. Cook et al. argue that Kosslyn et al.'s models did not process "spatial" representations and that input-output correlations rather than properties of spatial relations encoding processes explain the performance of the models. This article provides conceptual and analytic rebuttals of those criticisms.

Brain↗

PubMed1992

Hemispheric specialization for skilled perceptual organization by chessmasters.

The right cerebral hemisphere may be relatively specialized for parsing simple visual stimuli according to default rules, such as the Gestalt laws of perceptual organization, whereas the left cerebral hemisphere may be relatively specialized for overriding such default rules. We extend this model to 'semantically rich domains' by performing a divided-visual-field experiment on 16 chessmasters. Such subjects are able to recall and recognize complex chess positions by chunking the basic elements of the stimuli--the chess pieces--into meaningful groupings according to certain rules that are specific to the semantic structure of the chess domain. We show that the right hemisphere is superior to the left at parsing according to the default rules of chess chunking, but that the left hemisphere is superior to the right at grouping pieces together in violation of those rules. These results suggest that the right hemisphere is better able to acquire and apply new sets of default parsing rules for specific contexts. We conclude, consistent with other neuropsychological evidence, that the right hemisphere is critical for chess skill.

Adolescent↗

PubMed1992

Categorical versus coordinate spatial relations: computational analyses and computer simulations.

Results of 4 sets of neural network simulations support the distinction between categorical and coordinate spatial relations representations: (a) Networks that were split so that different hidden units contributed to each type of judgment performed better than unsplit networks; the reverse was observed when they made 2 coordinate judgments. (b) Both computations were more difficult when finer discriminations were required; this result mirrored findings with human Ss. (c) Networks with large, overlapping "receptive fields" performed the coordinate task better than did networks with small, less overlapping receptive fields, but vice versa for the categorical task; this suggests a possible basis for observed cerebral lateralization of the 2 kinds of processing. (d) The previously observed effect of stimulus contrast on this hemispheric asymmetry could reflect contributions of more neuronal input in high-contrast conditions.

Computer Simulation↗