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Several recent studies have reported neglect of both the left and right sides of space ("dual neglect"), depending upon particular circumstances, within single patients. A further case, EL, who sustained a unilateral lesion of the left parietal lobe, is reported here. EL shows left neglect in reading and object naming tasks, and right neglect in cancellation, drawing, oral spelling, and copying tasks. In addition, the side neglected can be altered by cueing EL to start copying on the right rather than the left, and by parsing visual displays so that they contain single or multiple objects. EL neglected the left side of single object representations and the right side of representations in which stimuli were coded as separate perceptual objects. We discuss relations between representations of space within and between perceptual objects, the effects of attentional cueing on these spatial representations, and their relation to activation within each cerebral hemisphere.

We examined the effects of plane rotation, task, and visual complexity on the recognition of familiar and chimeric objects. The effects of rotation, with response times increasing linearly and monotonically with rotation from the upright, were equivalent for tasks requiring different degrees of visual differentiation of the target from contrasting stimuli--namely, (1) deciding whether the stimulus was living or nonliving (semantic classification), (2) deciding whether the stimulus was an object or a nonobject (object decision), and (3) naming. The effects of complexity, with shorter response times to more complex stimuli, were most apparent in semantic classification and object decision and were additive with the effects of rotation. We discuss the implications of these results for theories of the relationship between the process of normalization and the determining of object identity.

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