Did you hear it? Our vision and hearing is not very reliable

New York: Can you always accurately tell where in your neighbourhood a sound, say of a cracker burst, originated? If you say yes, you are wrong, according to the findings of a new study. Our vision and hearing are not as reliable as we might think, the study by life scientists at University of California-Los Angeles (UCLA) said.

“Our basic sensory representation of the world -- how information from our eyes and ears is processed by neurons in the brain -- is inaccurate,” said senior study author Ladan Shams. With her colleagues, Shams conducted the research to examine whether humans’ “spatial localisation” ability -- that is, whether we can immediately and accurately perceive where an object is located -- is as well-honed as we believe it to be.

In the study, subjects were asked to sit facing a black screen, behind which were five loudspeakers. Mounted on the ceiling above was a projector capable of flashing bursts of light onto the screen, at the same spots where the speakers were located. The scientists played brief bursts of sound and triggered flashes of light, in various combinations, and asked participants to identify where they originated.

Read: Demystifying phantom pains, cross-connections in the brain

The subjects fared poorly when the light and sound were played alone. “We didn’t expect these spatial errors; they’re very counterintuitive,” Shams said.

The study participants did, however, answer much more accurately when the flashes and noise were played simultaneously at the same location. “The brain is wired to use information from multiple senses to correct other senses. The saying is true: ‘If you want to hear better, put your glasses on’,” Shams said.

The study was published in the journal PLOS Computational Biology.