Study Shows Schizophrenia Limits Understanding of Body Language
Understanding the meaning behind a person's posture or body movement comes easily to many people and helps guide how we react to others socially.
But people with schizophrenia, even those who have mild to moderate symptoms and take medications, are not fluent in understanding body language, according to a University of Iowa-led study that included investigators Nirav Bigelow, Ph.D., Sergio Paradiso, M.D., Ph.D., and Nancy C. Andreasen M.D., Ph.D. The results appear in the April 2006 issue of Schizophrenia Research.
Previous studies conducted by Paradiso and Andreasen showed that patients with schizophrenia have trouble deciphering emotion from human facial expressions. However, it was not well understood whether this perception problem extended to other socially relevant clues, said Sergio Paradiso, the study's corresponding author and assistant professor of psychiatry in the UI Roy J. and Lucille A. Carver College of Medicine.
"As we interact with people, we make judgments that we're not consciously aware of," Paradiso said. "If we see a coworker hunched over and don't see his face, we may approach him cautiously because we think something might be wrong and perhaps we can help. We don't see the face, but we glean information from the body language. People with schizophrenia are not as good at extracting this kind of information to guide their social interactions."
The study included 14 people without schizophrenia and 20 people with schizophrenia who were taking medication and had mild to moderate symptoms.
"Unfortunately, standard treatment for schizophrenia does not appear to be capable of improving perception that helps in being social with others," Paradiso said.
The inability to perceive body language also appears unrelated to a person's level of intelligence. "Many people with schizophrenia, including those who are very bright, remain awkward in social situations," Paradiso added.
The study used innovative techniques, selected by the team and implemented by Bigelow and Andreasen, to test the study participants' reactions to human posture and movement. Bigelow, a former UI fellow in psychiatry, is now a clinical neuropsychologist at the Indianapolis Community North Hospital, and Andreasen is the Andrew H. Woods Chair of Psychiatry at the UI.
In one test, participants watched a video of human bodies in motion. The images were manipulated so that no facial features or body shapes could be seen. Instead, only points of light, attached to the joints of the people on the tape, were visible as they moved. Based on the speed and pattern of the bright dots, individuals without schizophrenia and healthy volunteers were asked to determine if the motion depicted joy or sadness, for example. The study found that individuals with schizophrenia could not accurately decipher these emotions.
Study participants also viewed still film clips of complex social scenes in which the actors' faces were erased. The participants then viewed the same clips with the faces reinstated. People with schizophrenia did not improve their performances in identifying the overall mood of the people in the scene.
"The film clip test showed that patients with schizophrenia have problems with both taking advantage of extra information that is conveyed by the human face and with deciphering socially relevant stimuli that are not conveyed by facial expression," Paradiso said.
Whether people with schizophrenia can learn to perceive body posture and other social clues has not been studied in detail. Paradiso said the question is an important one to be examined at a neuroscientific level - to see whether, with adequate rehabilitation, regions of the brain can take over and support social perception abilities.
"The idea of other circuits taking over the brain for specific mental capacities is not new. There's some degree of redundancy in the brain so that when a specific faculty is affected another part of the brain attempts to take over. It may occur in people who have had a stroke, usually through rehabilitation," he said.
Next, UI investigators will examine more closely how medication used to treat schizophrenia affects social perception of emotionally laden material and whether different medications have different effects.