It all started with Molyneux asking Locke about seeing after “recovery from blindness”:
“Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal. Suppose then the cube and sphere were placed on a table, and the blind man made to see: query, whether by his sight, before he touched them, could he distinguish and tell which was the globe and which the cube?”
And the scientific study of S.B. who, after more than fifty years of blindness, regained vision1. (See our blog for the philosophical approach.)
So, do people who are born blind and who gain vision later in life recognise the world around them?
Yes and no. Gregory and Wallace found that S.B. recognised simple shapes, like circles and squares, as well as ordinary objects, such as chairs and tables, and their size. S.B. read print numbers, print capital letters, and the time on a large clock hanging on the wall. He struggled with complex information: for example, faces and facial expressions meant nothing to him if he did not hear the person’s voice. S.B. could not read the small print letters, and he did not recognise depth and movement. In traffic, he closed his eyes and functioned as if he were still blind; he was surprised by how the moon looked, and he was fascinated by reflections.
It was known long before S.B. that correspondences between the senses exist, but not that information transfers between them in shape and object recognition2.
Gregory and Wallace found that S.B. recognised by vision information that he already knew by touch – indeed, for the first time, demonstrating that information transfers from touch to vision.
Following Gregory and Wallace’s first scientific study on crossmodal recognition, researchers continue to investigate what information is and is not transferred and between which senses. Revisiting Molyneux, they typically measure with what accuracy, speed, or both people recognise information already familiar by touch and now explored by vision. An example of information that transfers between the senses is shape however information that is retained in one sense only is colour. Researchers are also investigating crossmodal plasticity in the brain. They typically scan what brain areas are active in people with one sense missing and people with all senses intact. An example of brain plasticity in people who are born blind is auditory information that activates both the auditory and visual areas (compared with only the auditory in the fully sighted).
When Gregory revisited the historical cases of people who have gained vision, he found that all, perhaps except one, had sad endings3. However, our knowledge from scientific studies allows us to change all that: for example, for people who lose vision later in life and who do not have the same option as S.B. – to function in traffic as if they were still fully sighted. To ensure that people who are partially sighted successfully combine information from low vision and touch. And to ensure that children with and without sensory disabilities learn well together. For an example of sharing sensory experiences in art, please see “Shaping Shapes” and “Please Touch the Art“.
See our blog for Activities; especially 4-6.
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1Gregory, R. L., & Wallace, J. G. (1969). Recovery from Early Blindness A Case Study. Experimental Psychology Society Monograph, No. 2. See: https://www.richardgregory.org/papers/recovery_blind/recovery-from-early-blindness.pdf
2An example of a correspondence between the senses is the sound of spoken words and visualshapes: later known as the “bouba/kiki-effect”.
3Gregory, R. L. (2003). Seeing after blindness. Nature Neuroscience, 6(9), 909-910. See: https://faculty.washington.edu/gboynton/publications/gregory-newsandviews03.pdf
