Schizophrenia Bulletin Advance Access originally published online on September 6, 2006
Schizophrenia Bulletin 2007 33(3):831-842; doi:10.1093/schbul/sbl040
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Effortful Cognitive Resource Allocation and Negative Symptom Severity in Chronic Schizophrenia
2 Veterans Affairs San Diego Healthcare System (116B), 3350 La Jolla Village Drive, San Diego, CA 92161
3 Department of Psychiatry, University of California, San Diego
4 Department of Psychology, University of New Mexico, Albuquerque
5 Department of Psychiatry, University of Pennsylvania
1 To whom correspondence should be addressed; tel: 858-552-8585 ext. 7768, fax: 858-642-6416, e-mail: egranholm{at}ucsd.edu.
Background: The relationship between negative symptoms, early visual information–processing deficits, and effortful processing resource allocation was investigated. Methods: Older patients with chronic schizophrenia (n = 58) and healthy controls (n = 71) participated. Pupillary responses were recorded during performance of the span of apprehension task (blocks of 3- and 10-letter arrays) as an index of resource allocation or mental effort during the task. Results: Patients and controls showed larger pupillary responses in higher relative to lower processing loads both during array processing and just prior to array onset (preparation). Both groups, therefore, invested more cognitive effort preparing for and then processing larger arrays. A subgroup of patients with abnormally small pupillary responses and impaired performance showed greater negative symptom severity relative to a subgroup of patients with normal pupillary responses. Smaller pupillary responses in the patients were also significantly correlated with greater negative symptom severity, independent of positive symptom severity. Patients with reduced effortful resource allocation, therefore, exhibited greater negative symptomatology. A subgroup of patients with normal pupillary responses still showed impaired detection accuracy relative to controls, suggesting that reduced cognitive effort or resource allocation problems cannot account for impairments in early visual information processing in this subgroup. Conclusions: The study illustrates important relationships between cognitive effort and performance that can impact conclusions about the nature of cognitive impairments and associations between negative symptoms and neurocognition in schizophrenia.
Keywords: schizophrenia / negative symptoms / pupillary responses / resource allocation / information processing
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