title: Delay discounting and task performance consistency in patients with schizophrenia.
abstract: To study impaired goal-oriented behavior in schizophrenia (SZ), we used a delay discounting task, which consists of a series of choices between receiving a small immediate or larger delayed reward. Few studies of delay discounting have evaluated response consistency (R(2)), which is especially relevant in SZ because of documented inconsistency in task performance. We calculated the rate of discounting (k) and R(2) in SZ (n=35) and healthy controls (HC; n=21). Using a criterion value of R(2)>0.60 to define consistent performance allowed us to compare discounting in consistent SZ and HC, as well as in inconsistent SZ. Groups did not differ significantly in smoking. Compared to HC, consistent SZ showed greater delay discounting. Both groups exhibited similar patterns of decreasing immediate choices across trial categories, although the decrease was less for SZ. Separate analyses on smokers and non-smokers showed that this group difference was carried by the non-smokers. Inconsistent SZ discounted more than HC and consistent SZ, but their aberrant pattern of choices casts doubt on the validity of their calculated k values.
authors.affiliation: Department of Psychology, The University of Alabama at Birmingham, Birmingham, AL 35294-1170, United States.
authors.forename: Rosalyn Eve
authors.initials: RE
authors.lastname: Weller
authors.affiliation: Department of Psychology, The University of Alabama at Birmingham, Birmingham, AL 35294-1170, United States; Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham, Birmingham, AL 35294-0017, United States.
authors.forename: Kathy Burton
authors.initials: KB
authors.lastname: Avsar
authors.affiliation: Department of Psychology, The University of Alabama at Birmingham, Birmingham, AL 35294-1170, United States.
authors.forename: James Edward
authors.initials: JE
authors.lastname: Cox
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham, Birmingham, AL 35294-0017, United States; Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, AL 35294-2182, United States.
authors.forename: Meredith Amanda
authors.initials: MA
authors.lastname: Reid
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham, Birmingham, AL 35294-0017, United States.
authors.forename: David Matthew
authors.initials: DM
authors.lastname: White
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham, Birmingham, AL 35294-0017, United States. Electronic address: alahti@uab.edu.
authors.forename: Adrienne Carol
authors.initials: AC
authors.lastname: Lahti
mesh_terms: D000328:Adult; D002755:Choice Behavior; D005260:Female; D006801:Humans; D007175:Impulsive Behavior; D008297:Male; D009483:Neuropsychological Tests; D012201:Reward; D012565:Schizophrenic Psychology; D012907:Smoking / Q000523:psychology; D013647:Task Performance and Analysis; D013997:Time Factors; D014029:Tobacco Use Disorder / Q000523:psychology
keywords: Decision making; Executive function; Intertemporal