The unified and coherent preattentive perception of facial and vocal emotions is disturbed in schizophrenia patients, in comparison with non-schizophrenic psychotics and healthy persons. This is shown by psychiatrist dr. Sjakko de Jong in his dissertation ‘Seeing Voices and Hearing Faces, Multisensory Emotion Perception in Schizophrenic and non-Schizophrenic Psychosis Patients’. De Jong defended this thesis on February 12th, 2014 at Tilburg University.
With his research, De Jong has shown that this disturbance in the multisensory emotion process partly explains why schizophrenia patients suffer from perception disorders and have social disabilities. This has to do with the preattentive sensory processing of emotions, the processing of emotions that occurs before the involvement of attention-controlled perception. “It makes sense that when you can’t integrate what you see and hear from a person, there may be miscommunication and delusions”, de Jong says.
Congruence and incongruence
De Jong examined 150 subjects, divided into schizophrenia patients, non-schizophrenic psychotic patients and healthy individuals, with computer-controlled tests. The subjects heard a vocal emotion at the same time they saw a facial emotion. Then, they had to indicate which emotion they heard.
As expected, healthy people showed a good working preattentive integration of the facial and vocal emotions in congruence conditions. They performed well, when the vocial emotion matched the facial emotion. They have more difficulty with incongruent facial and vocal emotions (eg, happy voice - scared face). A similar effect was found in non-schizophrenic psychotic patients.
"However, schizophrenia patients deviated from these two groups," says De Jong. "They experienced difficulties with incongruent facial and vocal emotions to the same degree as the other two groups, but performed much worse in congruent emotions."
De Jong expanded the tests with additional visual and auditory distractors, such as numbers between the eyebrows on the pictures with facial emotions and beeps in the auditory part of the test. Now, the subjects were asked to answer questions about the numbers or beeps in addition to indicating the voice emotion. The integration of the facial and vocal emotions in healthy patients decreased, as previous research at the Tilburg University had already demonstrated. But with the schizophrenia patients, this was not the case.
De Jong: "We have shown that the integration of emotions by patients with schizophrenia did not decrease with the distractions. The results were similar to the condition without the extra distraction. There were even cases in which the integration slightly increased. The selective attention mechanisms that protects healthy people from (excessive) processing of unimportant stimuli, does not appear to work.” Non-schizophrenic psychosis patients had scores intermediate between the healthy subjects and schizophrenia patients in these tests.
The interaction of preattentive and attentive
De Jong then examined the link between the preattentive multisensory emotion processing with attentive neurocognition and social cognition. "Again, we found a difference between schizophrenia patients and healthy people. In healthy people, the three domains were found to be consistent with a model in which they were predictable and strongly interrelated. When someone performed well on one component, he was also performing well on the others. De Jong showed that in schizophrenia patients the multisensory emotion processing was completely independent of the neurocognition and social cognition. “This is a surprising result”, says de Jong. Further research is needed to determine why the multisensory emotion is unrelated to the other two domains.
The exploratory study by De Jong has seized 10 years of his time, but according to the psychiatrist it was definitely worth it. De Jong: "Our results provide the first indications of how multisensory emotion perception problems can result in social disabilities. I hope this is an incentive for more research and deeper knowledge so that we can develop a solution”