Abstract
Are observers aware of their own visual limitations? We reported previously that observers do not estimate accurately the extent to which their visual acuity would decline as luminance decreases (Brooks, et al., VSS'05). We now explore the accuracy of observers' estimates of their depth perception. After dark adapting, 30 naive young observers estimated their depth thresholds using a modified Howard-Dolman apparatus. Observers sat to the side of the apparatus and adjusted the lateral separation of two vertical sticks to estimate the average alignment error that would exist if they were to perform the task in the conventional manner (sitting at the end of the apparatus and adjusting the stick in depth). Depth thresholds were estimated for both monocular and binocular vision at increasing luminances from 0.0325 to 325 cd/m2. After dark adapting again, observers performed the task in the conventional manner (adjusting the stick in depth) under the same viewing conditions. As expected, depth thresholds were significantly lower with binocular viewing and at high luminance. Comparing estimated and actual thresholds revealed that although observers recognized that two eyes would be better than one, they failed to appreciate the extent to which binocular viewing enhances depth perception. In general, observers' estimated their monocular performance fairly accurately but overestimated binocular depth thresholds at all but the lowest scotopic luminance. That is, observers underestimated their stereoacuity. These findings add to the evidence that observers cannot accurately estimate their visual abilities in familiar conditions.
Funding was received from an REU grant from NSF.