Effects of parietal lesions in humans on color and location priming

To determine whether the parietal lobes contribute to the selection of nons patial features known to be processed in the ventral stream, the current st udy examined the effect of chronic unilateral parietal lobe lesions in huma ns on color and location priming. Patients and normal controls performed a go/no-go color discrimination task in which either the same color and diffe rent color pairs of stimuli (prime and probe) were projected sequentially e ither in the same hemifield or in opposite hemifields. Control subjects and patients both showed independent effects of color and location priming. In the patients, primes in either field produced color priming for target pro bes in the ipsilesional field but not for probes in the contralesional fiel d. This observation implicates the parietal cortex in processing activated codes of stimulus attributes not only for spatial information but also for visual features processed in the ventral visual pathways.