Precision and accuracy of oculocentric direction for targets of different luminances

The precision and accuracy of specifying oculocentric directions were assessed by successively partitioning an 8.3° space in the right field into a series of perceptually equal fractional spaces and then matching each partitioning target’s direction in the left field. Three observers performed this task for four target luminances, ranging from 0.04 to 43 cd/m2. The results show that luminance has virtually no effect on either the precision or accuracy of spatial partitioning; essentially no effect was obtained even when, for one observer, target luminance was reduced to nearly the absolute threshold. We interpret these data in terms of oculocentric direction’s role in mediating visual behaviors.