The optical, neurological, and visual cortical processing of the eye, as well as the minimal size of a high-contrast item that enables us to recognize it, all place limits on recognition acuity. Motion adaptation can alter how large objects are perceived to be. When viewing motion that is retreating or approaching, successive stimuli are seen to be growing or contracting, accordingly. According to reports, ensuing variations in perceived size have an effect on recognition acuity. For a study, researchers sought to find out what causes the occurrence and whether such acuity changes were reliable.

They examined the impact of looming and receding motion adaptation on the sharpness of packed tumbling-T stimuli. They measured how important crowding was, how susceptible people were to motion adaptation, and if pupil size and eye movements may have confusing effects. Targets seemed bigger and had better clarity after adaptation to the retreating motion (–0.037 logMAR). Although objects seemed smaller as a result of adaptation to impending motion, it did not result in the predicted decline in acuity but rather a little improvement (–0.018 logMAR).

Furthermore, there was no correlation between each observer’s individual perceived size change after adaptation and the extent of their altered visual acuity. Finally, they found no proof that crowding, fixation stability, or pupil size were connected to adaptation-induced acuity increases. Visual acuity was slightly improved by adaptation to motion, but surprisingly, it was unrelated to perceived size. They proposed that motion adaptation may enhance sharpness through accidental effects on sensitivity, similar to those resulting from blur adaptation, which shifts sensitivity to higher spatial frequency-tuned channels, ruling out fixation and pupillary activity.