The foregoing solution to the problem of VDC faces challenges on multiple, empirical fronts. First, there is evidence that proprioceptive signals from the extraocular muscles make a non-trivial contribution to estimates of eye position, although the gain of efference copy is approximately 2.4 times greater (Bridgeman &amp; Stark 1991). Second, in the autokinetic effect, a fixed luminous dot appears to wander when the field of view is dark and thus completely unstructured. This finding is inconsistent with theories according to which retinotopic location and efference copy are the sole determinants of eye-relative direction. Third, the hypothesized compensation process, if psychologically real, would be highly inaccurate since subjects fail to notice displacements of the visual world up to 30% of total saccade magnitude (Bridgeman et al. 1975), and the locations of flashed stimuli are systematically misperceived when presented near the time of a saccade (Deubel 2004). Last, when image displacements concurrent with a saccade are large, but just below threshold for detection, visually attended objects appear to “jump” or “jiggle” against a stable background (Brune and Lücking 1969; Bridgeman 1981). Efference copy theories, however, as Bridgeman observes,