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Imagination can change what we actually see and hear, according to a new study.

Scientists at the Karolinska Institutet in Sweden found that what people imagine hearing or seeing "in their heads" can change their actual perception.

The findings, published in the journal Current Biology, may provide new insight into how our brains combine information from different senses.

"We often think about the things we imagine and the things we perceive as being clearly dissociable," lead study author Christopher Berger, doctoral student at the Department of Neuroscience, said in a statement.

"However, what this study shows is that our imagination of a sound or a shape changes how we perceive the world around us in the same way actually hearing that sound or seeing that shape does. Specifically, we found that what we imagine hearing can change what we actually see, and what we imagine seeing can change what we actually hear," Berger explained.

The study involved 96 healthy participants. Researchers conducted a series of experiments that make use of illusions in which sensory information from one sense changes or distorts one's perception of another sense.

In the first experiment, participants experienced the illusion that two passing objects collided rather than passed by one-another when they imagined a sound at the moment the two objects met. The second experiment revealed that the participants' spatial perception of a sound was biased towards a location where they imagined seeing the brief appearance of a white circle. The third experiment revealed that the participants' perception of what a person was saying was changed by their imagination of a particular sound.

Researchers said the latest findings might be useful in understanding the mechanisms by which the brain fails to distinguish between thought and reality in certain psychiatric disorder like schizophrenia.  The results could also be used in research on brain computer interfaces, where paralyzed individuals' imagination is used to control virtual and artificial devices.

"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" Professor Henrik Ehrsson, the principle investigator behind the study, said in a news release.