title: Planning Decrements in Healthy Aging: Mediation Effects of Fluid Reasoning and Working Memory Capacity.
abstract: OBJECTIVE
  Although age-related differences in planning ability are well known, their cognitive foundations remain a matter of contention. To elucidate the specific processes underlying planning decrements in older age, the relative contributions of fluid reasoning, working memory (WM) capacity, and processing speed to accuracy on the Tower of London (TOL) planning task were investigated.
  
  
  METHODS
  Mediation analyses were used to relate overall and search depth-related TOL accuracy from older (N = 106; 60-89 years) and younger adults (N = 69; 18-54 years) to age and measures of fluid reasoning, WM capacity, and speed.
  
  
  RESULTS
  For overall planning, fluid abilities mediated the effects of age, WM capacity, and speed in older adults. By contrast, fluid abilities and WM capacity mediated each other in younger adults. For planning accuracy under low demands on the depth of search, WM capacity was specifically important in older age, whereas younger adults recruited both WM capacity and fluid reasoning. Under high search-depth-demands, fluid abilities underlay the cognitive operations critical for resolving move interdependencies in both age groups.
  
  
  CONCLUSIONS
  Fluid abilities and WM capacity undergo significant changes from younger to older age in their unique contribution to planning, which might represent a mechanism whereby planning decrements in older age are brought about.
authors.affiliation: lena.koestering@uniklinik-freiburg.de.
authors.forename: Lena
authors.initials: L
authors.lastname: Köstering
authors.affiliation: Department of Psychology, University of Freiburg, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Leonhart
authors.affiliation: Department of Psychology, University of Cologne, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Stahl
authors.affiliation: Department of Neurology, University Medical Center, Freiburg Brain Imaging Center, BrainLinks-BrainTools Cluster of Excellence, and.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Weiller
authors.affiliation: Department of Neurology, University Medical Center, Freiburg Brain Imaging Center, BrainLinks-BrainTools Cluster of Excellence, and.
authors.forename: Christoph P
authors.initials: CP
authors.lastname: Kaller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D056344:Executive Function; D006801:Humans; D008570:Memory, Short-Term; D008875:Middle Aged; D013850:Thinking; D055815:Young Adult
keywords: Cognitive aging; Fluid reasoning; Mediation analysis; Planning; Processing speed; Tower of London; Working memory.