Differential prosocial behavior without altered physical responses in mirror sensory synesthesia
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2016-07-01
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en
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Abstract
In synesthesia specific sensory stimuli lead to unusual, additional experiences. Mirror-sensory
synesthetes mirror the pain or touch that they observe in other people on their own body. It has not been
examined whether physical, bodily responses accompany it. We hypothesized that synesthetes would show
deviations in hormonal levels and physiological responses when viewing arousing pictures. We expected
more extreme ratings of pleasantness and arousal of the pictures due to the synesthetic experience.
Previous studies have yielded contradictory evidence on whether mirror sensory synesthetes
demonstrate enhanced empathic behavior. Altruism is related to empathy, but it has not yet been
examined in mirror sensory synesthesia. We hypothesized that synesthetes would show more empathic
and altruistic behavior and enhanced theory of mind, and that this would relate to the physiological and
rating responses to arousing pictures.
We diagnosed mirror-sensory synesthetes with an established touch-interference paradigm and
asked them to rate pictures with positive, negative, and neutral context for valence and arousal while their
heart rate, skin conductance, and pupil dilation were recorded. Cortisol levels were assessed. Altruism
was tested with a one shot Dictator's Game where participants divided money between themselves and a
second player. Questionnaires on empathy, theory of mind, personality traits, and pain perception were
completed. 18 mirror-sensory synesthetes and 18 controls participated.
Our results show that mirror sensory synesthetes are more altruistic and more strongly impacted
by positive and negative images. The stronger the reported synesthesia, the stronger the effect on the
pictures ratings. We did not find evidence for differential physical responses to arousing pictures.
Synesthetic experience does not alter overall perception about pain but makes mirror-sensory-synesthetes
develop personality characteristics similar to synesthetes of other types (enhanced extraversion and
openness to new experience). Synesthetes scored higher only on some of the empathy measures,
highlighting the need for further investigation on the hypothesis.
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Faculteit der Sociale Wetenschappen