Washington: A close up shows Serena Williams' eyes tensely shut; her mouth wide open, teeth bared and her face livid. Now zoom out: The tennis star is on the court, racquet in hand, fist clenched in victory. She's not angry. She's ecstatic, having just beaten her sister Venus at the 2008 US Open.

Context helps interpret facial emotions accurately, according to this research.

“Strip away the context, and it is difficult to accurately perceive emotion in a face,” argues Lisa Feldman Barrett, psychologist at the Northwestern University and Harvard, who led the study.

For instance, the Transportation Security Administration...is “training agents to detect threat or deception using methods based on the idea that a person's internal intentions are broadcast on the face,” says Barrett, the journal Directions in Psychological Science reports.

In case of misinterpretation, “millions of training dollars might be misspent,” says Barrett. This means that a misguided psychological notion could be putting public safety at risk, according to a Northwestern statement.

Context is what places such expression in a proper perspective. A scowl can be read as fear if a dangerous situation is described or as disgust if the posture of the body indicates reaction to a soiled object.

Barrett's study, based on a review of dozens of studies, refutes the contention that there are six to 10 basic emotions, which can be read easily in an image detached from a face by anyone, anywhere.

(Agencies)