Schizophrenic Perception of Faces Schizophrenia Thesis

Excerpt from Thesis :

28 subjects comprised the normal control group. They were recruited through a newspaper ad and had no histories of Axis I psychiatric disorders.

The subjects were shown images on a computer screen for 13, 26, 52, or 104 ms, sometimes upright and sometimes inverted, and were asked to indicate, by pressing one of two keys on a keyboard, whether the image of a face or a tree was located on the left side or on the right side of each drawing.

Results

Schizophrenia patients exhibited significantly less accuracy when they tried to detect upright and inverted faces than normal controls did. Stimulus durations made no difference as the deficit existed across all durations.

Unlike the detection of faces, tree detection was not significantly different for the two groups. A reduced stimulus inversion effect in schizophrenia was shown primarily in faces but not in tree detection. The only interaction shown to be significant was between group and stimulus orientations (upright or inverted). Other interactions were not significant. Tree detection was more accurate in normal controls than in patients, but this finding was independent of stimulus orientation. Antipsychotic drugs that patients were taking did not appear to be correlated with their accuracy in face detection.

Conclusion

The first stage of facial information processing appears to be impaired in schizophrenia. This would be the first and most basic perception in the brain's facial information processing system. The researchers argue that face recognition is "categorically different from recognition of other visual objects" and that a deficit in recognizing a face as a face in schizophrenia patients indicates a problem or impairment in the FFA part of the brain. They argue this because the problem is with detecting faces and not with detecting other visual objects. The researchers state, "The results of this study suggest that this is the case" (Chen et al., 2007, p. 5). For schizophrenics the face inversion effect was significantly greater than for tree inversion. The researchers argue this also indicates something wrong in the first stage of visual detection of faces. Schizophrenia patients exhibited very little inversion effect when they were detecting trees. Their stimulus inversion effect for trees did not significantly differ from controls. But the patients did show significant differences in inversion effect when detecting faces. This "suggests an impairment specific to facial information processing in schizophrenia" (p. 6) and suggests that poor face detection in schizophrenia is linked to dysfunctional FFA (an impairment in the fusiform face area in the temporal cortex). Schizophrenics may be using a different or "less efficient, cortical mechanism" for processing facial information, or it may be they cannot access the normally "highly efficient, face-specific brain system" (p. 7).

Discussion possible weakness in this study was the use of a tree as a visual object other than a face. Other visual objects might have been used such as a house or a car, for example. The outline of a tree is not at all like the outline of a face. Rather than comparing faces with trees, a visual object with an outline more similar to that of a face for the other visual object could make for more meaningful findings in a future study. In future studies it would also make sense to find out what effect the inability to detect a face as a face would have on recognizing identity, emotional expression, gender, age, race, etc. The researchers state, "How inefficient face detection in schizophrenia contributes to the recognition of identity and expression of faces and to general social functioning should be used as topics for further studies" (Chen et al., 2007, p. 6). Although the authors do not mention specific treatments for FFA impairment, the use of a micro-chip implant (such as are already being implanted in the brain for blindness and deafness) is an exciting possibility for correcting schizophrenia perceptual deficits in…

Sources Used in Document:

References

Chen, Y., Norton, D., Ongue, D. And Heckers, S. (2007). Inefficient face detection in schizophrenia. Schizophrenia Bulletin, 10, 1093, 1-8.

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