Japanese researchers have discovered a new bistable perceptual phenomenon in digital characters, such as Arabic numerals.
- Partial occlusion of a digit causes bistable interpretations, because “the visual input does not contain enough information.”
- Bistability does not depend on low-level visual information, such as simple visual features, or high-level information, such as semantics.
- The researchers hope to expand their study to better understand and more precisely locate the areas of the brain that generate perceptual bistability.
“Numbers, that is, the semantic expressions of numbers, allow us to have an exact representation of the quantity of things. Visual processing of numbers plays an indispensable role in the recognition and interpretation of numbers.” This is what scientists from the National Institute of Physiological Sciences (Japan) wrote in work published in the journal Journal of VisionIn this work, they analyzed how visual information from numbers is processed to achieve semantic understanding.
Bistable perceptual phenomenon: partial occlusion causes visual ambiguities
To conduct the study, the authors recruited healthy adults and conducted a behavioral experiment using visual adaptation tasks. “This task paradigm allowed us to examine how exposure to specific types of visual input biased perception.” For the intervention, the team designed a special character, called an occluded numeric digit. Experience shows that partial occlusion of some numeric digits introduces bistable interpretations. In short, a numeric digit can be recognized as having multiple semantic meanings, usually two. This happens because “the visual input does not contain enough information to allow us to make a unique semantic interpretation of the occluded numeric character,” explained Junxiang Luolead author of the research.
“Visual adaptation selectively reduces neuronal sensitivity”
Then, using the visual adaptation method, the team investigated the origin of this bistability in participants. They found that after prolonged presentation of normal numerical digits to the visual system, volunteers tended to report that they saw a single digit that was biased relative to the adapting digit. “Visual adaptation selectively reduces the neuronal sensitivity of a certain stage of visual processing to a certain class of visual stimuli. (…) We hope to extend this study using physiological methods to better understand and more precisely localize the brain areas that generate perceptual bistability,” the researcher said.
