title: Assessment of planning performance in clinical samples: Reliability and validity of the Tower of London task (TOL-F).
abstract: OBJECTIVE
  Executive deficits are frequent sequelae of neurological and psychiatric disorders, but their adequate neuropsychological assessment is still a matter of contention, given that executive tasks draw on a multitude of cognitive processes that are often not sufficiently specified. In line with this, results on psychometric properties of the Tower of London, a task measuring planning ability as a prototypical executive function, are equivocal and furthermore lacking completely for adult clinical populations.
  
  
  METHODS
  We used a structurally balanced item set implemented in the Tower of London (Freiburg version, TOL-F) that accounts for major determinants of problem difficulty beyond the commonly used minimum number of moves to solution. Split-half reliability, internal consistency, and criterion-related concurrent validity of TOL-F accuracy were assessed in patients with stroke (N = 60), Parkinson syndrome (N = 51), and mild cognitive impairment (N = 29), and healthy adults (N = 155).
  
  
  RESULTS
  Across samples, mean split-half and lower-bound indices of reliability of accuracy scores were adequate (r ≥ .7) or higher. Compared to a subset of healthy controls matched for age, sex, and education levels, deficits in planning accuracy emerged for all three clinical samples.
  
  
  CONCLUSIONS
  Based on consistently adequate reliability and a good criterion-related validity of accuracy scores, the TOL-F demonstrates its utility for testing planning ability in clinical samples and healthy adults. Using item sets systematically accounting for several determinants of task difficulty can thus significantly enhance the contended reliability of executive tasks and provide an opportunity to resolve the underspecification of cognitive processes contributing to executive functioning in health and disease.
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; Biological and Personality Psychology, Department of Psychology, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany. Electronic address: lena.koestering@uniklinik-freiburg.de.
authors.forename: Lena
authors.initials: L
authors.lastname: Köstering
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; Biological and Personality Psychology, Department of Psychology, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany.
authors.forename: Charlotte S M
authors.initials: CS
authors.lastname: Schmidt
authors.affiliation: Freiburg Brain Imaging, University of Freiburg, Germany; Department of Neuroradiology, University Medical Center, University of Freiburg, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Egger
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Amtage
authors.affiliation: Freiburg Brain Imaging, University of Freiburg, Germany; Department of Psychiatry and Psychotherapy, University Medical Center, University of Freiburg, Germany.
authors.forename: Jessica
authors.initials: J
authors.lastname: Peter
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; Department of Psychiatry and Psychotherapy, University Medical Center, University of Freiburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Klöppel
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany.
authors.forename: Lena-A
authors.initials: LA
authors.lastname: Beume
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Hoeren
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Weiller
authors.affiliation: Department of Neurology, University Medical Center, University of Freiburg, Germany; Freiburg Brain Imaging, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany.
authors.forename: Christoph P
authors.initials: CP
authors.lastname: Kaller
mesh_terms: D000368:Aged; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000523:psychology; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D020734:Parkinsonian Disorders / Q000175:diagnosis / Q000523:psychology; D011340:Problem Solving; D011594:Psychometrics; D015203:Reproducibility of Results; D020521:Stroke / Q000175:diagnosis / Q000523:psychology
keywords: Executive function; Mild cognitive impairment; Neuropsychological tests; Parkinson disease; Psychometrics; Stroke