title: Simulating category learning and set shifting deficits in patients weight-restored from anorexia nervosa.
abstract: OBJECTIVE
  To examine set shifting in a group of women previously diagnosed with anorexia nervosa who are now weight-restored (AN-WR) and then apply a biologically based computational model (Competition between Verbal and Implicit Systems [COVIS]) to simulate the pattern of category learning and set shifting performances observed.
  
  
  METHODS
  Nineteen AN-WR women and 35 control women (CW) were administered an explicit category learning task that required rule acquisition and then a set shift following a rule change. COVIS was first fit to the behavioral results of the controls and then parameters of the model theoretically relevant to AN were altered to mimic the behavioral results.
  
  
  RESULTS
  Relative to CW, the AN-WR group displayed steeper learning curves (i.e., hyper learning) before the rule shift, but greater difficulty in learning the new categories after the rule shift (i.e., a deficit in set shifting). Hyper learning and set shifting deficits in the AN-WR group were not associated and differentially correlated with clinical measures. Hyper learning in the AN-WR group was simulated by increasing the model parameter that represents sensitivity to negative feedback (δ parameter), whereas the deficit in set shifting was simulated by altering the parameters that represent changes in rule selection and flexibility (λ and γ parameters, respectively).
  
  
  CONCLUSIONS
  These simulations suggest that multiple factors can impact category learning and set shifting in AN-WR individuals (e.g., alterations in sensitivity to negative feedback, rule selection deficits, and inflexibility) and provide an important starting point to further investigate this pervasive deficit in adult AN.
authors.affiliation: Psychology and Research Service, Veterans Administration San Diego Healthcare System.
authors.forename: J Vincent
authors.initials: JV
authors.lastname: Filoteo
authors.affiliation: Beckman Institute, University of Illinois at Urbana-Champaign.
authors.forename: Erick J
authors.initials: EJ
authors.lastname: Paul
authors.affiliation: Department of Psychology, University of California Santa Barbara.
authors.forename: F Gregory
authors.initials: FG
authors.lastname: Ashby
authors.affiliation: Department of Psychiatry, University of Colorado Anschutz Medical Campus.
authors.forename: Guido K W
authors.initials: GK
authors.lastname: Frank
authors.affiliation: Department of Psychological Sciences, Purdue University.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Helie
authors.affiliation: Department of Psychiatry, University of California San Diego.
authors.forename: Roxanne
authors.initials: R
authors.lastname: Rockwell
authors.affiliation: Department of Psychiatry, University of California San Diego.
authors.forename: Amanda
authors.initials: A
authors.lastname: Bischoff-Grethe
authors.affiliation: Department of Psychiatry, University of California San Diego.
authors.forename: Christina
authors.initials: C
authors.lastname: Wierenga
authors.affiliation: Department of Psychiatry, University of California San Diego.
authors.forename: Walter H
authors.initials: WH
authors.lastname: Kaye
mesh_terms: D000328:Adult; D000856:Anorexia Nervosa / Q000523:psychology*; D001835:Body Weight; D003071:Cognition; D003072:Cognition Disorders / Q000150:complications*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007858:Learning; D008959:Models, Neurological