Singularity Hub: What counts as a sense in the first place is not clear cut. by Edd Gent
'Sight, hearing, taste, smell, and touch make up the traditional five senses, but our sense of balance and the ability to track the movement of our own body (proprioception) are both key sensory inputs. While often lumped in with touch, our temperature and pain monitoring systems could potentially qualify as independent senses.
'These senses are also not as concrete as we probably believe. Roughly 4.4% of the population experiences synesthesia — where the stimulation of one sense simultaneously produces sensations in another. This can result in people perceiving colors when they hear sounds or associating shapes with certain tastes, demonstrating the potential fluidity of our senses.
'In recent years, scientists have taken advantage of this fluidity to develop workarounds for those who have lost one of their senses. The pioneering work of American neuroscientist Paul Bach-y-Rita in the 1960s demonstrated the plasticity of the human brain. He created a chair that translated a video feed into vibrations on 400 small touchpads pressed against a person’s back, which allowed congenitally blind patients to detect faces, objects, and shadows.'
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