Imagination can affect sight, sound senses

A new research from Karolinska Institute in Sweden has unveiled that our imagination can change our actual perception of what we hear and see. The study of 96 healthy participants revealed that what we imagine hearing can alter what we actually see, and what we imagine seeing can affect what we actually hear, according to the finding published in the journal Current Biology. The research explores the historic question in psychology and neuroscience about how our brains combine information from all the different senses. "We often think about the things we imagine and the things we perceive as being clearly dissociable," says the lead author of the study Christopher Berger, doctoral student at the Department of Neuroscience in Karolinska Institute. To achieve credible results, the team examined a series of experiments that used illusions in which sensory information from one sense distorts or changes a person's perception of another sense. At the first examination, participants dealt with the illusion of two passing objects hitting each other rather than passing each other when they imagined a sound at the moment of collision between the two objects. The second experiment involved in the volunteers’ spatial perception of a sound that was biased towards a location where they imagined seeing the brief appearance of a white circle. In the third stage of experiment, the participants' perception of what a person was saying was altered by their imagination of a particular sound. The study sheds light on the mechanisms by which the brain is not able to distinguish between thought and reality in several psychiatric disorders such as schizophrenia. "This is the first set of experiments to definitively establish that the sensory signals generated by one's imagination are strong enough to change one's real-world perception of a different sensory modality," said Professor Henrik Ehrsson, the principle investigator of the study.