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Abstract:
A number of studies have demonstrated that some stimulus
attributes can be processed without awareness in the contralesional
visual field of patients exhibiting spatial attention deficits.
However, it is unclear to what extent complex stimulus attributes
modulate the rate of extinction. We tested a patient with left
visual field extinction in an emotion judgment task involving
upright or inverted faces. Happy or sad schematic faces were
presented either unilaterally or bilaterally. Stimuli in the
bilateral presentation condition had either the same or different
expressions and both were either upright or inverted. The
participant was instructed to indicate happy, sad, or nothing for
each side. Detection was nearly perfect for unilateral trials.
Conversely, for bilateral trials inverted faces were detected and
correctly identified more often than upright faces and the error
rate was higher when the two faces had the same rather than
different expressions. In addition, error rates in the
contralesional field were lower for sad compared with happy faces.
These results replicate and extend previous findings that
extinction rates can be modulated by complex stimulus
characteristics. The relative contributions of stimulus properties,
task relevance, task difficulty, and face-specific processing (in
particular expression analysis) to the allocation of attention to
the contralesional field will be discussed.
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