Washington: Contrary to the idea that blind people learn about animal appearance from sighted people's descriptions, a recent study claims that with the help of logical inference blind adults can get a rich insight into what hippos and sharks look like.
"First person experience isn't the only way to develop a rich understanding of the world around us," said Judy Kim, the corresponding author of the study published in the Journal of Proceedings of the National Academy of Sciences.
While some previous research has shown that blind people do have knowledge of things like light and colour, researchers still have little understanding of what blind people know about appearance and how such information is learned. Some studies suggest that people born blind remember verbal facts, like 'flamingos are pink,' so the research team wanted to investigate further.
The researchers presented 20 blind and 20 sighted adults with animal names and asked participants to order animals by size (smallest to largest) and height (shortest to tallest); sort animals into groups based on shape, skin texture and colour pick which animal out of a group is unlike the others in shape, and choose from various texture options ("Does a hippo have feathers, fur, skin or scales?").
Overall, blind and sighted participants organized animals in similar ways and agreed on which physical features were most likely to be observed within animal groups.
For example, blind and sighted participants judged that dolphins are similar in shape to sharks and sloths are similar in texture to grizzlies. 15 out of 20 blind and 19 out of 20 sighted participants judged elephants to be bigger than rhinos. But the groups also showed some differences.
Blind and sighted participants disagreed most about the dimension that was easiest for sighted people to describe in words - animal colour. Sighted participants created groups for white, pink, black, black and white, brown and grey animals, and they easily labelled these groups according to their primary colours.
By contrast, sighted people had a hard time verbally describing their shape groupings; they used many words and did not agree with each other. Nevertheless, blind people created similar shape groups to the sight but did not make consistent colour groups.
Researchers found that to deduce what animals looked like, blind people relied on similar biological classifications that scientists use to group species. This strategy works very well for shape and texture: birds, for example, have feathers and a characteristic winged shape. Such inference works less well for colour because many very different animals are white (e.g., swans, polar bears and sheep).
The main conclusion is that blind people develop rich and accurate ideas about appearance based on inference. "It's sometimes assumed that the senses and direct experience are the best way to learn about the world. What the findings show is that linguistic communication can give us rich and accurate knowledge, even knowing that at first glance seems 'visual.'" said, one of the researchers, Marina Bedny.
