For most of us, it is difficult to imagine what it must be like to be a synesthete – that is, someone who experiences a crossing over of their senses, such as seeing sounds as colours, or perceiving shapes as having tastes. However, according to a new study in Consciousness and Cognition, it is actually relatively easy for people with normal perception to have a synesthetic experience (of the sound-to-vision variety). It merely takes a few minutes of visual deprivation, followed by a visual imagery task. The findings are not merely intriguing – and a fun idea for a psychology class experiment – they also have a bearing on the main theories for how synesthesia occurs.

Across three studies, involving dozens of non-synesthetic undergrad students, the University of Michigan psychologists Anupama Nair and David Brang asked their volunteers to sit with their eyes closed in a completely darkened room for five minutes. After this, the imagery task began, which was almost identical through the three studies: dozens of times the students heard one of four words followed by a letter, such as “symmetrical T” or “curve A”, and their job was to visualise the letter and judge whether it had the mentioned feature (so, in the previous examples, whether “T” is symmetrical and whether  “A” contains any curves). The other two feature words used in the task were “diagonal” and “closed”, referring to whether the letter had a diagonal line in it or an entirely enclosed feature.

The purpose of the darkness was to remove competing visual perceptions, while the idea of the imagery task was simply to raise the activity levels within the visual cortex (visual imagery is known to recruit brain areas that overlap with those involved in visual perception).

Read the full article at the British Psychological Society.