Reaction time as a function of peripheral retinal locus around fovea: effect of stimulus size.

Using targets of four sizes between 18' and 116' at a fixed luminance of 5.8 cd/m2, human visual reaction times (RT) were measured on a circle at 30 degrees eccentric to the fovea. A foveal and 12 peripheral retinal loci were explored, covering the range between 0 degrees and 330 degrees in steps of 30 degrees units on a circle about the fovea. RT decreased significantly by the stimulation to the quadrant retinal loci between nasal and superior side. RT decreased as a function of increasing target size and the amount of decrement was relatively larger in the periphery than in the fovea.