Purchase this article with an account.
Caryn Nearnberg, Glen McCormack; The Convergence Depth Cue and Hand Guidance. Invest. Ophthalmol. Vis. Sci. 2013;54(15):187.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Our lab previously found that when subjects tracked, with the unseen hand, a binocularly-fixated vertical line oscillating in depth in dark surrounds, tracking accuracy dropped significantly at lower target oscillation rates 1. The present study tested whether this rate effect also occurred when subjects periodically reached to the moving line target from a rest position.
Eighteen normally binocular young adults binocularly fixated a line oscillating in depth at rates of 0.03125Hz or 0.25Hz, at oscillation magnitudes of 4Δ, 8Δ, and 12Δ about a 33cm distance. The line target was generated in an electronic mirror haploscope. In separate trials subjects manually tracked the line with the unseen hand, or periodically made transient reaches from a rest position to the oscillating line target. Hand responses were electronically recorded. Target oscillation rate and magnitude were randomized.
A repeated measures ANOVA was performed on response magnitude for the factors of rate, task, and stimulus magnitude. Stimulus magnitude significantly affected response magnitude (F=12.3, p=.0001), but did so equally in both tasks (F=1.23, p=.29) and in both rates (F=1.10, p=.33), so the results were averaged over stimulus magnitudes. Rate had a different impact on tracking than on reaching (F=10.843, p=0.0012). Mean tracking responses increased with rate from 2.4Δ to 5.2Δ (t=4.73, p=.000004) while reaching responses did not increase with rate (2.48Δ to 2.52Δ, t=.074, p=.941).
Reaching to near objects is influenced by instantaneous vergence angle while manual tracking of near objects is influenced by vergence rate. 1 G. L. McCormack, S. Han, C. Meyer, & L. Deng. Manual versus Perceptual Estimates of Vergence-induced Motion-in-Depth. Invest. Ophthalmol. Vis. Sci. 2010 51: E-abstract 1826.
This PDF is available to Subscribers Only