Colour constancy impairments in patients with lesions of the prestriate cortex.

Colour matching and colour constancy were studied in seven patients and 46 control subjects. Subjects were required to match Munsell Colour Chips presented under either identical or different illumination. Three of the patients had deficits in colour constancy, i.e. failure to compensate for the change in the wavelength composition of the illumination. Two of the patients with defective constancy had suffered bilateral cortical damage to the posterior lingual and fusiform gyri, and one patient had a lesion restricted to the same regions of the right hemisphere. Our observations indicate that these cortical areas, which include part of putative human area V4, play an important role in colour constancy

Colour constancy impairments in patients with lesions of the prestriate cortex.

Colour matching and colour constancy were studied in seven patients and 46 control subjects. Subjects were required to match Munsell Colour Chips presented under either identical or different illumination. Three of the patients had deficits in colour constancy, i.e. failure to compensate for the change in the wavelength composition of the illumination. Two of the patients with defective constancy had suffered bilateral cortical damage to the posterior lingual and fusiform gyri, and one patient had a lesion restricted to the same regions of the right hemisphere. Our observations indicate that these cortical areas, which include part of putative human area V4, play an important role in colour constancy

Short-term memory for colour following posterior hemispheric lesions in man.

Short-term memory for colour was studied in five patients with circumscribed posterior hemispheric lesions. It was impaired independently of colour discrimination in one and more than colour discrimination in two patients. Two patients were normal in colour short-term memory, one with normal and one with deficient colour discrimination performance. Deficient performance in colour short-term memory was associated with bilateral lesions of the inferior occipitotemporal junction including the lateral part of the fusiform gyrus or with a unilateral lesion of the left parieto-occipital convexity. An additional colour constancy deficit was found in the former but not the latter condition. Thus, colour short-term memory can be affected independently of colour discrimination or colour constancy, and may depend on at least two distinct neural circuits