Location-specific versus hemisphere-specific adaptation of processing selectivity.

Current theories of cognitive control assume that processing selectivity is adjusted according to the utility of processing task-irrelevant stimulus features. Consistently, interference evoked by flanker stimuli is reduced when the proportion of incompatible trials--in which flankers are associated with an incorrect response--is increased. Consistent with the idea that the cerebral hemispheres select processing strategies independently of each other, Corballis and Gratton (2003) demonstrated that flanker interference for stimuli presented in either the left or right visual hemifield is affected by the ratio of compatible and incompatible target-flanker pairings presented in the same--but not in the other-hemifield. Presenting stimuli at four different locations, we demonstrated independent effects of the ratio of compatible and incompatible trials for stimulus locations in different hemifields as well as for stimulus locations within the same hemifield. Independent selectivity adjustment regarding the left and right visual hemifields thus appears to be a special case of a larger class of location-specific adaptation effects and might not be informative regarding hemisphere-specific processing.