Online control of rapid target-directed aiming using blurred visual feedback.

ABSTRACT

The accuracy and precision of target-directed aiming is contingent upon the availability of online visual feedback. The present study aimed to examine the visual regulation of aiming with blurred vision. The aiming task was executed using a stylus on a graphics digitizing board, which was translated onto a screen in the form of a cursor (representing the moving limb) and target. The vision conditions involved the complete disappearance or blur of the cursor alone, target alone, and cursor+target. These conditions involved leaving the screen uncovered or covering with a diffusing sheet to induce blur. The distance between the screen and sheet was increased to make the blur progressively more severe (0 cm, 3 cm). Results showed significantly less radial and variable error under blurred compared to no vision of the cursor and cursor+target. These findings were corroborated by the movement kinematics including a shorter proportion of time to peak velocity, more negative within-participant correlation between the distances travelled to and after peak velocity, and lower spatial variability from peak velocity to the end of the movement under blurred vision. The superior accuracy and precision under the blurred compared to no vision conditions is consistent with functioning visual regulation of aiming, which is primarily contingent upon the online visual feedback of the moving limb. This outcome may be attributed to the processing of low spatial-high temporal frequencies. Potential implications for low vision diagnostics are discussed.