Do focal neocortical lesions hamper short-term recognition of visual spatial patterns?

A hundred and forty-three patients with focal - mainly neocortical - hemiphere-damage (subdivided in 4 groups according to the side of the damaged hemisphere and the presence/absence of visual field defect) and 70 controls, were given a 20-sec delay recognition test of complex spatial visual patterns. There was one free delay condition and two conditions with interference from visual material of either similar or quite dissimilar patterns to that of memoranda. The results provided by two co-variance analyses are: (i) the comparison of the hemisphere-damaged groups with controls show a significant memory decay of both right groups only when there was perceptual interference from similar patterns; (ii) the comparisons between hemisphere-damaged groups fail to elicit any significant difference in the three memory conditions. There appears to be no specific neocortical area involved in the first steps of memory processing of spatial informations and the interference engendered by interpolated perceptual activity is material-specific.