 A different approach to Molyneux’s problem involves the use of sensory substitution devices, developed in the context of corporeal mobility or reading (Morgan, 1977). Learning how to use sensory substitution systems has been considered a good approximation to Molyneux’s problem, since such systems present information normally handled by one modality, such as vision, to another sense, typically audition or touch, using forms of coding novel to the user. Experiments with sensory substitution systems show that subjects need some time to learn to distinguish and identify objects, and this has been interpreted as a confirmation of the position of Molyneux and Locke. Some researchers have stressed the fact that a sensory aid is not, strictly speaking, a new modality, and that to learn to use such devices is only an approximation to Molyneux’s problem, depending as it does upon the raising of similar issues.