Why two eyes are better than one: The two views of binocular vision.

Abstract

Despite centuries of research on the topic, the answer to the question "'Are two eyes significantly better than one, independent of stereopsis?" is still uncertain. In this investigation, steps are taken toward answering the question in a behavioral context. Three sets of experiments are reported in which human binocular and monocular performance are compared in a variety of exteroceptive and visuomotor tasks. In all of the experiments, two eyes facilitated performance. The findings suggest that the binocular system is able to detect the matching information, that is, the concordance, in the monocular optic arrays and to use that information to increase visual efficiency. Furthermore, stereopsis was not found to be important in the performance of visuomotor skills in three dimensions when the subjects were free to move their heads. Thus, the results indicate that an important ecological benefit of binocular frontal vision is having binocular concordance, rather than having binocular disparity.

The contribution of stereo vision to one-handed catching

“…By consequence, the advantage of binocular vision apart from stereopsis or disparity is very limited if not negligible, which confirms earlier statements that the major advantage of having two eyes seems to be stereoscopic depth discrimination (Fielder and Moseley 1996) and/or retinal disparity. This is, however, in contrast with a series of experiments by Jones and Lee (1981), which showed that concordant or matching information from both eyes is a significant advantage of binocular vision. In this respect it has to be noticed that Jones and Lee (1981) did not use interceptive actions in their experiments, which could explain the discrepancy in results.…”

“…This is, however, in contrast with a series of experiments by Jones and Lee (1981), which showed that concordant or matching information from both eyes is a significant advantage of binocular vision. In this respect it has to be noticed that Jones and Lee (1981) did not use interceptive actions in their experiments, which could explain the discrepancy in results. Other work by Lee et al (1991Lee et al ( , 1992, Heuer (1993) and Laurent et al (1996) suggested that a tau function (i.e.…”

“…Under normal binocular viewing, individuals with poor stereoscopic vision and inadequate retinal disparity could also use concordant information or convergence next to tau (present in both eyes) to attune their catch (Jones and Lee 1981). Given that binocular performance did not exceed monocular catching, they did not take advantage of this additional available information.…”

“…Similarly Steeves et al (2000) showed that enucleated observers had not developed compensatory mechanisms for lacking binocular vision. Jones and Lee (1981) suggested, however, that binocular stereopsis should only play a part when the head is stationary. Is the head free to move, depth information could arise from the optical flow in one eye.…”

Stereopsis and binocular rivalry.

“…These include detection of stimuli and brightness summation (reviewed in Blake & Fox, 1973;Blake, Sloane, & Fox, 1981) and several perceptual and visual motor tasks (Jones & Lee, 1981). These phenomena probably reflect the contribution of the Stereopsis pathway, as all of them require a fairly close match between the monocular inputs.…”