Shadow acts as an extension of our body, study finds

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The Independent Online

The relationship between people and their shadows extends beyond merely feeling alone and blue together.

The relationship between people and their shadows extends beyond merely feeling alone and blue together.

Two Italian psychologists have found the shadow acts like an extension of the body by becoming a distant reference point that helps people perform dextrous tasks. They sayshadows cast by the body have a profound effect on visual perception, which can be easily distracted by a nearby shadow.

Francesco Pavani and Umberto Castiello, of Trento University, investigated the influence of shadows by testing 10 volunteers in an experiment that measured the time it takes to react to an electrical stimulus to the forefinger or the thumb. When the volunteers felt a tingle in their forefinger they had to release a pedal under their toe, and when they felt a tingle in their thumb they had to release pressure on a pedal under their heel.

The scientists tried to interfere with the thought processes involved by flashing red lights near the volunteers' hands. The red lights only affected a person's reaction time when they flashed near the person's shadow, whichconfused the volunteers and interfered with their ability to make a quick decision.

The results indicated that interfering with a person's shadow affects that person's sense of space and can distract them from carrying out a specific task quickly and correctly. Previous research suggested the "body schema" - the internal picture people have of their bodies - can actually extend beyond their skin.

The scientists say in the journal, Nature Neuroscience: "These findings suggest that shadows cast by a person's own body parts can bridge the gap between personal and extra-personal space... the body schema can also extend to incorporate shadows cast by an individual's body parts."

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