A patient with progressive posterior cortical atrophy (PCA)
was examined on several tests of visual cognition. The patient
displayed multiple visual cognitive deficits, which included
problems identifying degraded stimuli, attending to two or more
stimuli simultaneously, recognizing faces, tracing simple visual
stimuli, matching simple shapes, and copying objects. The patient
was also impaired in identifying visual targets contained at
the global level within global–local stimuli (i.e., smaller
letters that compose a larger letter). Although the patient
denied any conscious awareness of the global form, he nevertheless
displayed a normal pattern of global interference when asked
to identify local level targets. Thus, the patient processed
the global information despite not being consciously aware of
such information. These results suggest that global–local
processing can take place in the absence of awareness. Possible
neurocognitive mechanisms explaining this dissociation are
discussed. (JINS, 2002, 8, 461–472.)