Brief stimuli localization in visual periphery.

Experiments were carried out to establish the effect of stimulus eccentricity and the kind of reference structure on the localization of brief stimuli in the visual periphery. In Experiment 1 the effect of eccentricities up to 55 degrees to the left and to the right of the fixation point on stimulus localization was studied. Systematic errors were obtained, the stimuli being mislocated nearer the fixation point than they were actually presented. The angular size of errors increased with the increase of stimulus eccentricity. In Experiment 2 the subjects had to localize the stimuli against three different background structures (scales). The results showed that error magnitude decreased when scales with clearly visible cues were used. The possible involvement of stimulus direction perception and of the identification of the scale element nearest to the perceived event is discussed.