Biomedical subjects

S P Vecera

Publications and source records attributed to S P Vecera.

2 recordsLinked to original sources

PubMed1994

Does visual attention select objects or locations?

Much research supports location-based attentional selection, but J. Duncan (1984) presented data favoring object-based selection in a shape discrimination task. Does attention select objects or locations? We confirmed that Duncan's task elicits selection from spatially invariant object representations rather than from a grouped location-based representation. We next asked whether this finding was due to location-based filtering; the results again supported object-based selection. Finally, we demonstrated that when Duncan's objects were used in a cued detection task the results were consistent with location-based selection. These results suggest that there may not be a single attention mechanism, consistent with Duncan's original claim that object-based and location-based attentional selection are not mutually exclusive. Rather, attentional limitations may depend on the type of stimulus representation used in performing a given task.

Adult↗

PubMed1993

Dissociated overt and covert recognition as an emergent property of a lesioned neural network.

Covert recognition of faces in prosopagnosia, in which patients cannot overtly recognize faces but nevertheless manifest recognition when tested in certain indirect ways, has been interpreted as the functioning of an intact visual face recognition system deprived of access to other brain systems necessary for consciousness. The authors propose an alternative hypothesis: that the visual face recognition system is damaged but not obliterated in these patients and that damaged neural networks will manifest their residual knowledge in just the kinds of tasks used to measure covert recognition. To test this, a simple model of face recognition is lesioned in the parts of the model corresponding to visual processing. The model demonstrates covert recognition in 3 qualitatively different tasks. Implications for the nature of prosopagnosia, and for other types of dissociations between conscious and unconscious perception, are discussed.

Agnosia↗