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This paper develops the hypothesis of different roles of the two hemispheres in imaginal processes. A test designated the "o'Clock Test" is proposed, which contains closely confrontable perceptual and imaginal tasks. It enables examination of the abilities both to generate mental images and to explore them in their right and left halves (R + L Condition). This test was used to examine two patients, one severely affected by hemi-inattention resulting from a right posterior lesion, and the other with a selective deficit of imagery due to a left occipital lesion. The former demonstrated left neglect in both perceptive and imaginal capacities, while the latter was able to perform correctly only the perceptive tasks. These results suggest that the right hemisphere has functions of organization and spatial exploration at both perceptive and imaginal levels, and that the left hemisphere's role is to generate mental images.

Memory coding processes can be divided according to their attentional requirement into "automatic" and "effortful". The aim of current research was to explore both automatic and effortful processes in early and late stages of Alzheimer type dementia. Patients were classified on the basis of restrictive clinical and neuropsychological criteria, in order to pinpoint possible specific impairments in the two patients' subgroups. The present paper reports preliminary data about 15 mildly and 15 severely demented patients. Statistical analysis showed that both the automatic and the effortful coding processes are impaired at the late but also at the early stages of dementia.