In a new study, scientists have established that hypnosis can trigger "synesthetic" experiences - where one sense triggers the involuntary use of another - within an average brain. The findings ruled out the popular perception that people with synesthesia have extra connections in their brain.
Instead, it suggested that their brains might simply do more 'cross talking', which could be induced by changing inhibitory processes in the average brain.
Titled, "Induced cross-modal synesthetic experience without abnormal neuronal connections," the research was conducted by an international group that includes Cohen Kadosh, previously a doctoral student at Ben-Gurion University of the Negev.
Synesthesia (known as synesthetes) patients experience abnormal interactions between the senses.
For example digit-color synesthesia, for instance, will experience certain numbers in specific colors (for example, they might experience the number seven as red).
Scientists have attributed the phenomenon to the existence of extra connections between brain areas in synesthesia, but the new study suggests otherwise.
The researchers saw that after inducing digit-color synesthesia, the volunteers had similar experiences to those undergone by real synesthetes in their everyday life.
"Our study shows that hypnosis can induce synesthetic experiences in people, suggesting that extra brain connections are not needed to experience cross-sensory interactions and that it is a change in inhibitory processes - more cross talk within the brain - that causes these experiences. This takes us one step closer to understanding the causes of synesthesia and abnormal cross-brain interactions," said Cohen Kadosh.
The study is published in the journal Psychological Science, the premiere publication of the Association for Psychological Society.