A DEVELOPMENTAL DEFICIT IN LOCALIZING OBJECTS FROM VISION

Abstract— We describe a college student, A. H., with a developmental deficit in determining the location of objects from vision. The deficit is selective in that (a) localization from auditory or tactile information is intact, (b) A H reports the identity of mislocalized objects accurately, (c) visual localization errors preserve certain parameters of the target location, and (d) visual localization is severely impaired under certain stimulus conditions, but nearly intact under other conditions. These results bear on the representation and processing of location information in the visual system, and also have implications for understanding developmental dyslexia.     

GUIDED VISUAL SEARCH IS A LEFT-HEMISPHERE PROCESS IN SPLIT-BRAIN PATIENTS

Abstract— Previous research has shown that split-brain (callosotomy) patients search through visual displays twice as fast as normal observers when items are divided evenly between visual hemifields, as though each disconnected hemisphere possessed its own attentional scanning system (Luck, Hillyard, Mangun, & Gazzaniga, 1989, 1994) Results from 3 split-brain patients in the present study indicate that the ability to limit search to a relevant subset of the visual display is lateralized to the left cerebral hemisphere. This ability to perform guided search was not shown in the right hemisphere, even when the search time in that hemisphere was superior to search time in the left Furthermore, guided search was observed for both hemifields in normal control observers. These findings suggest that, as with higher cognitive processes such as language, strategic visuospatial attentional processes are preferentially lateralized to the left cerebral hemisphere. The findings also imply that the callosum mediates guided search in the right hemisphere of normal subjects     

GROUPING BY PROXIMITY AND MULTISTABILITY IN DOT LATTICES:

Abstract— Gestalt phenomena have long resisted quantification. In the spirit of Gestalt field theory, we propose a theory that predicts the probability of grouping by proximity in the six kinds of dot lattices (hexagonal, rhombic, square, rectangular, centered rectangular, and oblique). We claim that the unstable perceptual organization of dot lattices is caused by competing forces that attract each dot to other dots in its neighborhood. We model the decline of these forces as a function of distance with an exponential decay function. This attraction function has one parameter, the attraction constant Simple assumptions allow us to predict the entropy of the perceptual organization of different dot lattices. We showed dot lattices tachistoscopically to 7 subjects, and from the probabilities of the perceived organisations, we calculated the entropy of each lattice for each subject. The model fit the data exceedingly well. The attraction constant did not vary much over subjects     

Coalescent argumentation

Coalescent argumentation is a normative ideal that involves the joining together of two disparate claims through recognition and exploration of opposing positions. By uncovering the crucial connection between a claim and the attitudes, beliefs, feelings, values and needs to which it is connected dispute partners are able to identify points of agreement and disagreement. These points can then be utilized to effect coalescence, a joining or merging of divergent positions, by forming the basis for a mutual investigation of non-conflictual options that might otherwise have remained unconsidered. The essay proceeds by defining and discussing argument, position and understanding. These notions are then brought together to outline the concept of coalescent reasoning.     

RESOLUTION OF LEXICAL AMBIGUITY BY EMOTIONAL STATE

Abstract— The role of emotion in the resolution of lexical ambiguity was investigated. Happy and sad subjects listened to a list of words that included homophones that had happy and neutral meanings (eg., presents-presence ) and homophones that had sad and neutral meanings (eg., mourning-morning ). Words were presented every 3 s, and subjects wrote down the words, as they heard them (Meaning could be identified by spelling in all cases). An interaction between emotional state and homophone category was observed. Sad subjects were more likely to write down sad meanings than were happy subjects. Results are discussed with reference to the literatures on both emotion and lexical access.