Dichoptic reading: The role of meaning in binocular rivalry

Abstract

These experiments sought to determine whether meaning influences the predominance of one eye during binocular rivalry. In Experiment I, observers tried to read meaningful text under conditions in which different text streams were viewed by the two eyes, a situation mimicking the classic dichotic listening paradigm. Dichoptic reading proved impossible even when the text streams were printed in different fonts or when one eye received a 5-sec advantage. Under nonrivalry conditions, the observers were able to read text presented at twice the rate usedfor dichoptic testing, indicating that cognitive overload does not limit performance under conditions of rivalry. In Experiment 2, observers were required to detect repeated presentations of a probe target within a string of characters presented to one eye. Although this task was easily performed under monocular viewing conditions, it proved difficult when the two eyes received dissimilar character strings. This was true regardless of whether the probed eye viewed nonsense strings, real words, or meaningful text. In a condition designed to encourage semantic processing of one eye's view, the observers were required to detect animal names as well as to detect the probe target. Performance remained inferior to that measured under monocular conditions. Even the observer's own name proved insufficient to influence the predominance of one eye under conditions of dichoptic stimulation. When two text strings were physically superimposed and viewed monocularly, essentially no probes were detected, indicating that the failure to see some probes during rivalry reflects a limitation unique to dichoptic viewing. These results contradict theories attributing binocular rivalry to an attentional process that operates on monocular inputs that have received refined analysis. This conclusion may be limited to rival stimuli whose meaning is defined linguistically, not structurally.The idea that binocular rivalry involves some sort of attentional mechanism is deeply rooted within the literature on visual perception. In his classic treatise on physiological optics, Helmholtz (1866/1962) dealt at some length with the parallels between rivalry and attention, and James (1890), in his chapter on attention, used rivalry to illustrate the hallmarks of what he called "sensorial attention." This putative link between rivalry and attention also appears in contemporary writings. In one of the most recent reviews of the literature on binocular rivalry, Walker (1978) maintained this tradition by arguing that "rivalry reflects central selective processes ... over and above the analysis of sensory information" (p. 387).Several lines of evidence can be marshaled in support of the view that rivalry involves central attentional mechanisms. For one thing, rivalry occurs even when the provoking stimuli are afterimages (e.g., Breese, 1899), a condition that effectively eliminates such peripheral factors as eye movements, retinal adaptation, or changes in accommodation as causes of rivalry. It is also known that

Binocular Rivalry and Motion Perception

“…In general, it is known that motion readily captures attention, so to the extent that rivalry represents a form of selective attention (e.g., Lack, 1978), the potency of a moving rival target may simply be a manifestation of attention's focus on things that move. For reasons detailed elsewhere (Blake, 1988), however, we are somewhat skeptical of an attentional account of rivalry. Instead, we believe the salience of moving rival targets has to do with the transients associated with motion.…”

“…In an important series of experiments, Fox and colleagues have shown that new visual information presented to an eye during rivalry is more dif cult to detect when the eye receiving that information is suppressed (Fox & Check, 1968;Wales & Fox, 1970). Similarly, large-scale changes in a suppressed rival stimulus itself may go completely undetected for several seconds, until that eye spontaneously achieves dominance (Blake, 1988;Blake & Fox, 1974). As characterized by Fox (1991), rivalry suppression operates nonselectively over a broad range of stimulus dimensions encompassing more than just the information represented in the suppressed stimulus.…”

Semantic and subword priming during binocular suppression

“…However, Blake argued that binocular rivalry may not have truly taken place in these experiments because the target words were flashed for only 400 ms. Subsequently, he used binocular rivalry to assess whether word meaning could influence the dominance of one eye during rivalry (Blake, 1988). In this experiment, observers viewed two different streams of letters, and the semantic content of the letter streams was varied to determine whether meaningful text could dominate nonsense text.…”

Binocular rivalry between emotional and neutral stimuli: A validation using fear conditioning and EEG

“…However, early positive findings have been criticized on methodological accounts, e.g., very brief presentation of the stimuli, unclear definition of dominance, and unclear reporting (see the review by Walker, 1978). One well-controlled study with negative findings which is frequently referred to in the literature used a dichoptic reading task (Blake, 1988). However, here the sentences and random strings appeared successively and reading was therefore impaired.…”