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.
Bibliographical noteFunding Information:
This research was supported by the National Institute of Mental Health, Grants MH53959-01 and MH60442-01A1; by the McDonnell-Pew Cognitive Neuroscience Center and the Arizona Cognitive Science Program of the University of Arizona; by the Center for Cognitive Sciences in conjunction with the National Science Foundation (GER 9454163), the Office of the Vice President for Research, and Dean of the Graduate School of the University of Minnesota. We wish to thank Chris Azorson for valuable discussion and Aimee Benton for help with data collection and tabulation. Earlier reports of this research were presented at Annual Meetings of the Cognitive Neuroscience Society, San Francisco (1996) and Boston (1997).
- Visual processing