Findings May Establish Test For Dementia Related Diseases Such as Alzheimer’s

When listening to or looking at others, most people don’t focus on the area of the face that will display true emotions, according to a report presented during the American Academy of Neurology’s 52nd Annual Meeting in San Diego, CA.

“Recognition of emotional displays on the lower face appear to be processed by the brain’s left hemisphere as part of the social — or learned — emotional system, whereas emotional displays on the upper face appear to be processed by the brain’s right hemisphere as part of the primary — or inborn — emotional system,” said Prodan. “These findings help us to gain a better understanding of the neurologic basis for affective communication, which will increase a physician’s ability to assess how diseases, such as stroke and dementia (such as Alzheimer’s), alter these functions.”

Researchers found that most people focus on the lower part of the face when dealing with others. However, if the person’s true feelings are “leaked” to the observer, they are more likely to appear on the upper face and could easily be missed. Previous studies have also shown that the lower portion of the face (nose, lips and cheeks) is more active than the upper face (eyes, brows and forehead) when individuals engage in deceitful social interactions.

“Perhaps the old adage ‘the eyes are the windows to the soul’ may be correct,” said Calin Prodan, MD, a neurology resident at the University of Oklahoma Health Sciences Center in Oklahoma City and lead author of the study.

“Humans learn in early childhood to manipulate facial emotions to make them appropriate to a given social situation which, in time, allows them to engage in deceitful behavior,” said Prodan. “For example, a person who is angry with their superior may display a ‘social’ smile rather than an angry scowl when asking for a raise.”

To better understand the brain’s recognition and processing of facial emotion, the researchers briefly showed 30 people line drawings of a human face displaying different emotions on the upper versus lower face, including happiness, sadness, anger, fear, surprise and neutral. Participants viewed the drawings in either their right or left visual fields, which offered clues to the side of the brain processing the information and its ability to do so.

Participants most often identified the lower face emotion, regardless of visual field. When subjects were instructed to focus on the upper face, they did so best when the pictures were shown to their left visual field (processed by the right side of the brain). However, most continued to identify the lower facial emotion when viewing in their right visual field (processed by the brain’s left side).

People may naturally focus on the lower face to aid in speech comprehension during conversation, especially in noisy environments. Social conventions may also play a role as many cultures consider it unacceptable to look someone directly in the eye — the “evil eye” belief. This may be interpreted as aggressive or threatening behavior, similar to those observed in some animal species.

“There is a natural learning curve starting in early childhood for acquiring the skills to read facial displays of emotion,” Prodan said. “We certainly can train ourselves to pay more attention to upper facial displays, which can help us read a person’s true emotional state. However, this can have a downside because of social conventions.”

Source: Eurekalert

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