In Brief

Those who have experienced traumatic brain injury (TBI) may fail to accurately assess others' emotions and as a result incorrectly infer whether other people's statements should be taken literally, suggests new research published in the July issue of Neuropsychology (Vol. 18, No. 3).

Even TBI patients with normal verbal ability may experience difficulty distinguishing between lies--untruths meant to be taken literally--and sarcasm, untruths that the listener is not expected to believe, says study author Skye McDonald, PhD, a psychology professor at the University of New South Wales in Australia. People with such deficits may need targeted rehabilitation to overcome them, she notes.

McDonald and her colleagues recruited 34 adults with TBI due to motor vehicle accidents, falls, assaults and other injuries, and located an equal number of uninjured people of the same age, education and gender as the TBI group.

Both groups of participants watched 15 videotaped interactions between two people, including five films featuring a sincere conversation and five showing one person being sarcastic. For example, one video shows a woman complimenting the hard work of her co-worker, but viewers are meant to infer from her emotion--anger--that she does not mean it.

In the remaining five videotapes, the interchange makes no sense if interpreted literally. For example, after one man asks his traveling companion if he remembered his passport, the sarcastic speaker brandishes the document and says, "Oh, yes, I tore it up and threw it away."

After watching each conversation, the participants wrote down the emotions, beliefs, intentions and meaning of each of the videotaped speakers.

The researchers found that participants with TBI made 30 percent more errors judging the mental states of the actors; for example, many failed to notice that the first vignette's co-worker was angry. Without that information, they could not infer the sarcasm of the actor.

Even TBI participants who could name the speaker's emotion often took what she said literally--for example many assumed the employee intended her co-worker to interpret her comment as a compliment. In effect, says McDonald, these participants confused a sarcastic remark with a lie.

The data underscore the importance of the frontal lobe--the area most often damaged in TBI--for processing social information, says McDonald. And while many people with TBI can read and speak at normal rates, their inability to interpret and apply information about a speaker's emotional state could lead to verbal miscommunication--which has implications for assessment and treatment, she says.

"We need to assess social competence in more detail in people with brain injuries in order to provide appropriate rehabilitation," says McDonald.