Sounds of moving objects change perceptions of body size

Sound and object motion can be used to change perceptions about body size, according to a new study by an international team involving UCL researchers. The study, published today in  PLOS ONE , found that introducing a mismatch between the predicted and actual outcome of an action, such as dropping a ball, can make people feel taller. When an object is dropped, the brain accurately predicts when it will hit the floor by considering the height from which it fell. Artificially lengthening the time it takes to hear the impact of the object on the ground leads people to update their perceived body height, making them feel taller. How humans perceive their body size is highly flexible, even beyond the ages when we stop growing. Most previous studies into this used sensory feedback on or about one's body but this study shows that even objects around us are used to compute our body size. The findings could have implications for studies already using sound for rehabilitation for people with poor proprioception - the sense of the position of parts of the body in relation to other parts - including for those who have Parkinson's Disease or have suffered a stroke.