Blind people can respond to emotional cues on other people’s faces and safely navigate around objects despite being unable to perceive them visually, according to ongoing research.
Neuroscientist Beatrice de Gelder at Holland’s Tilburg University has been working on various projects with multinational scientists, looking at affective blindsighted patients.
Physically there is nothing wrong with these people’s eyes, but part of their visual cortex in the brain does not function properly, due to a stroke or other trauma, leaving them blind in at least one eye.
“Blindsighted patients feel they’re totally blind,” said de Gelder in a press release presenting her research to a neuroscience congress in July. “But we’re finding they can still navigate around obstacles, and respond emotionally.”
People with normal eyesight (cortical vision) tend to empathize, for example they subconsciously synchronize their facial expressions with those of others. Previously, it was believed that this automatic response was triggered by visual perception.
In a 2009 study, de Gelder and colleagues used a partition to separate the images seen by the eyes of two patients with blindness in half of their visual fields. Then pictures of faces showing strong emotions like happiness and fear were shown to their blind side while their seeing eye was exposed to neutral expressions.
The participants’ empathic emotions were detected by measuring pupil dilation and facial muscles responses.
De Gelder and colleagues found that the patients imitated the faces that were loaded with emotion even though they could not see them. When asked, subjects said they were guessing what emotions the pictures portrayed.
Interestingly, the patients responded in the exact same manner when the same images were shown to their seeing eye.
So how is it possible for a person to see without seeing?
De Gelder was interviewed in season two of Morgan Freeman’s Through the Wormhole in the episode aired on July 6. The series sets out to explore various mysteries of existence and the universe.
According to de Gelder, the human visual system consists of at least nine different neural pathways. Cortical vision tends to overwhelm a person’s perception, but the activity of other background pathways can be detected in blindsighted people.
These subconscious mental pathways allow a person to sense emotions rather than see them, and appear to form the basis of a sixth sense.
“One should have a sympathetic ear to those noises about sixth sense because we don’t have a clear view yet about the abilities of the brain,” said de Gelder in the television program
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