Online control of rapid target-directed aiming under simulated low vision


It is well known that the accuracy and precision of target-directed aiming is dependent upon the availability of online visual feedback. However, there have been comparatively few studies to examine aiming under blurred vision, which may coincidentally simulate a diagnostic marker for low vision. Participants (n=10) executed target-directed aiming by using their upper-limb to displace a stylus on a graphics digitizing board, which was represented as a cursor on a screen along with the intended target. The vision conditions involved the complete disappearance or blur of the cursor alone, target alone, and cursor+target. These conditions involved uncovering or covering the screen with a diffusing sheet whose increasing distance from the screen made the blur more severe (0 cm, 3 cm). Data were normalized with respect to a standard full-field vision block. Results showed significantly less radial and variable error under blurred (0 cm, 3 cm) compared to no vision of the cursor and cursor+target, while there was no such advantage for vision of the target alone. The enhanced accuracy and precision under blurred compared to no vision coincided with a shorter proportion of time to peak velocity and more negative within-participant correlation between the distances travelled to and after peak velocity. We highlight the possibility for the online control of aiming using blurred visual feedback, which is specific to the limb and not necessarily the target. This outcome may be attributed to the capacity for processing low spatial-high temporal frequencies during movement.