2012 volume 41(8) pages 939 – 949
doi:10.1068/p7091

Cite as:
Grove P M, Ono H, 2012, "Horizontal/vertical differences in range and upper/lower visual field differences in the midpoints of sensory fusion limits of oriented lines" Perception 41(8) 939 – 949

Download citation data in RIS format

Horizontal/vertical differences in range and upper/lower visual field differences in the midpoints of sensory fusion limits of oriented lines

Philip M Grove, Hiroshi Ono

Abstract. O’Shea and Crassini (1982, Perception & Psychophysics 32 195–196) demonstrated that fusion persists for vertical lines with an orientation disparity of 8°, but diplopia is experienced in simultaneously presented horizontal lines with the same disparity. They concluded that the neural fusion process fuses larger horizontal disparities than vertical disparities. Kertesz criticised their demonstration because it did not quantify the possible motor component associated with fusing their counter-rotated images. Krekling and Blika argued that the demonstrated anisotropy is due to a disparity bias in the visual system, owing to the temporalward tilt of corresponding vertical meridians. We addressed these criticisms with a novel stimulus and presentation protocol, that rendered compensatory cyclovergence eye movements unlikely and explored a wide range of orientation disparities. We confirmed O’Shea and Crassini’s vertical/horizontal anisotropy in orientation fusion limits. In addition, our measurements of vertical lines showed that the distributions of fused responses as a function of orientation disparity in the upper and lower visual fields were shifted relative to each other. Therefore, the distributions of fusible orientation disparities are wider for vertical lines than horizontal lines and are relatively shifted as predicted if the fusional range is centred around the vertical horopter.
Keywords: fusion, orientation disparity, torsion, cyclodisparity, cyclovergence, stereopsis

Restricted material:

PDF Full-text PDF size: 974 Kb

Your computer (IP address: 54.163.158.99) has not been recognised as being on a network authorised to view the full text or references of this article. If you are a member of a university library that has a subscription to the journal, please contact your serials librarian (subscriptions information).