Proximal Figure Effects on Visual Acuity

Abstract

This study was designed to investigate the influence of the presence and orientation of figures proximal to an acuity measurement line. Each of 16 Ss served under four conditions: acuity line alone, acuity line with proximal figures parallel with it, acuity line with 45° proximal figures, and acuity line with 90° proximal figures. All proximal figures tested resulted in decreased efficiency of acuity processes. Orientation of the proximal figure was an important factor with greater influence for 45° and 90° than for the parallel line situation. These results support the Fry-Bartley principle that contour processes interfere with each other and indicate that the influence is directional in character.

Stimulus determinants of dynamic visual acuity: II. Effects of limiting the target surround.

“…The recognition of a visual acuity target, when observed under stable conditions, is affected by target type (4-6), contrast (7)(8)(9), luminous intensity (10,11), extent and relative luminance of the surround (12, 13), proximal contours (14,15), and position in the visual field (16,17). When these variables are allowed to covary, their effects are compounded.…”

Stimulus Determinants of Dynamic Visual Acuity. III. Effects of Proximal Borders and Limited Surround,

“…The ability to perceive a minimal target stimulus can be degraded b,' the presence of a visible, proximal border (21,22). The degree of interference by the proximal stimulus increases to a This has been demonstrated for the detection of a small disc near a bar (23), detection of a line between two dark bars (24), acuity for a Landolt ring surrounded by four dark bars (25), and acuity for a vernier target pliced between two lines oriented either parallel or perpendicular to the target (26).…”