Resolution Acuity is better than Vernier Acuity

Our impressive sensitivity to vernier offsets as compared to resolution acuity has long inspired vision researchers to study the phenomena in great detail. In this study we use the test-pedestal framework to compare resolution and vernier acuity. In these experiments the test stimulus is the same for both tasks, only the pedestals differ. When thresholds are expressed in common units of test strength, vernier acuity thresholds are higher (worse) than for resolution and contrast discrimination tasks over the range of pedestal strengths tested. This apparent reversal of sensitivity is actually consistent with expectations based on the presumed underlying visual mechanisms involved in the tasks.