First-sight recognition of touched objects shows that chicks can solve the Molyneux's problem

Abstract

If a congenitally blind person learns to distinguish between a cube and a sphere by touch, would they immediately recognise these objects by sight if their vision is restored? This question, posed by Molyneux in 1688, has puzzled philosophers and scientists. We overcame ethical and practical difficulties in the study of cross-modal recognition by using inexperienced chicks. We hatched chicks in darkness, exposed them to tactile smooth vs. bumpy stimuli in darkness and then tested them in a visual recognition task. At first sight, chicks previously exposed to smooth stimuli approached the smooth stimulus significantly more than those exposed to the bumpy stimuli. This shows that cross-modal recognition does not require multimodal experience. At least in precocial species, supra-modal brain areas already function at birth.