Temporal and spatial interference with vernier acuity

Abstract Vernier resolution is substantially reduced when onset asynchrony of the two lines of the target reduce the simultaneous exposure of both lines to 100 msec or less. It is show a that this reduction is caused by backward interference of the target component that remains exposed. Temporal interference of short-exposure vernier resolution is limited to the 150 msec following the target presentation and to a spatial region of about 10′ flanking the stimuli. Most effective interference is caused when line interfering stimuli are at a distance of 3–6′, not when they are superimposed on the vernier target. The orientation of the interfering lines is not critical. Quantitative analysis of the results eliminate ocular light scatter as the principal origin of the phenomena, and the fact that interference with vernier acuity still occurs with dichoptic testing rules out the retina as the site of interaction.