Biomedical subjects

David R Andresen

Publications and source records attributed to David R Andresen.

3 recordsLinked to original sources

PubMed2005

Does a causal relation exist between the functional hemispheric asymmetries of visual processing subsystems?

Past research indicates that specific shape recognition and spatial-relations encoding rely on subsystems that exhibit right-hemisphere advantages, whereas abstract shape recognition and spatial-relations encoding rely on subsystems that exhibit left-hemisphere advantages. Given these apparent regularities, we tested whether asymmetries in shape processing are causally related to asymmetries in spatial-relations processing. We examined performance in four tasks using the same stimuli with divided-visual-field presentations. Importantly, the asymmetry observed in any one task did not correlate with the asymmetries observed in the other tasks in ways predicted by extant theories. Asymmetries in shape processing and spatial-relations encoding may not be due to a common causal force influencing multiple subsystems.

Adult↗

PubMed2005

Interactive visual and postvisual processes and their roles in form-specific memory.

Effects of depth of encoding on form-specific memory were examined. After viewing words (e.g., "bear") presented centrally during initial encoding, participants completed word stems (e.g., "BEA") presented laterally and pattern masked during subsequent test. When the encoding task was perceptual, letter-case specific memory was not observed, unlike in previous experiments without pattern masking. However, when the encoding task required both perceptual and conceptual processing, letter-case specific memory was observed in direct right-hemisphere, but not in direct left-hemisphere, test presentations, like in previous studies without pattern masking. Results were not influenced by whether stems were completed to form the first words that came to mind or words explicitly retrieved from encoding. Depth of encoding may influence form-specific memory through interactive processing of visual and postvisual information.

Concept Formation↗

PubMed2002

Interhemispheric communication of abstract and specific visual-form information.

Pairs of letters were compared after being viewed in different visual fields (i.e. across-hemispheres, AH) or in the same visual field (i.e. within-hemisphere, WH). In an abstract-category comparison task, participants decided whether two letter exemplars belonged to the same abstract category (e.g. "k" and "K") or not (e.g. "k" and "P") and performed more accurately in AH trials than in WH trials. In a specific-exemplar comparison task, they decided whether two letters within the same abstract category were the same specific exemplars (e.g. "k" and "k") or not (e.g. "k" and "K") and performed more accurately in WH trials than in AH trials. This pattern of results was observed when the exemplars in a category were visually similar (e.g. "k" and "K", "a" and "a") but not when they were visually dissimilar (e.g. "a" and "A"). The reversed association technique was used to confirm the independence of subsystems underlying abstract category and specific-exemplar comparisons. Most important, the results support the theory that a specific-exemplar subsystem is more detrimentally affected by interhemispheric transfer of information than an abstract category subsystem.

Adult↗