After a stroke damaged parts of his brain, a 25-year-old man lost much of his ability to
experience disgust, according to a report in the November Nature Neuroscience. The specific
brain areas damaged in the stroke process all sorts of sensory and social cues for disgust, contends
a team led by neuroscientist Andrew J. Calder of the MRC Cognition and Brain Sciences Unit in Cambridge, England.
Prior studies had implicated these brain areas, the insula and putamen, only in perceiving
facial expressions of disgust.
The brain-damaged man, called NK by the researchers, displayed average intelligence and
good vision and hearing. Calder’s group compared his performance on emotion-recognition
tests with that of 20 adults with uninjured brains.
When shown pictures of faces expressing various emotions—anger, contempt, disgust, fear,
happiness, sadness, and surprise—NK erred frequently only in identifying instances of disgust.
NK also failed to recognize nonverbal sounds that trigger disgust, such as retching, whereas he
usually identified sounds linked to other emotions, such as laughter for happiness.
NK understands the concept of disgust, the researchers note. For instance, he knows that
certain pictures, such as an image of a filthy toilet, provoke the emotion of disgust in others.
However, he reports a much milder experience of disgust in reaction to descriptions of disgust-
provoking situations—eating chocolate shaped like feces or seeing a dead body, for example—than the adults without brain damage do.