title: Effects of aging on visual contour integration and segmentation.
abstract: OBJECTIVE
  Perception of circular disconnected contours requires the integration of relevant local orientation information across space and the suppression of irrelevant orientations. Using a detection of deviation from circularity (DFC) task, the present study examined whether the efficiency of either integrative or suppressive visual mechanisms, or both, declines with age.
  
  
  METHODS
  Younger and older observers' sensitivities in detecting the DFC of a contour formed by Gabors were compared in three conditions: when all elements were oriented tangentially to the contour, with and without the presence of randomly oriented background noise; and when they had alternated tangential and orthogonal orientations, without background noise.
  
  
  RESULTS
  In agreement with previous studies, the authors found that younger observers were not impaired in the mixed condition with respect to the tangential condition, suggesting the involvement of a high-level mechanism responding to the global closure information provided by tangential local orientations, even if they are interspersed with orthogonal ones. Instead, older observers were specifically impaired in the mixed condition, suggesting a reduced capability of suppressing nontangential information along the contour, and were also less efficient in suppressing irrelevant orientations in the background.
  
  
  CONCLUSIONS
  These results support the suggestion that, whereas integrative mechanisms are not affected by age, suppressive mechanisms are.
authors.affiliation: Department of General Psychology, University of Padua, Padua, Italy.
authors.forename: Clara
authors.initials: C
authors.lastname: Casco
authors.forename: Valentina
authors.initials: V
authors.lastname: Robol
authors.forename: Michele
authors.initials: M
authors.lastname: Barollo
authors.forename: Selene
authors.initials: S
authors.lastname: Cansino
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D055253:Color Vision / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology*; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D055254:Night Vision / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011594:Psychometrics; D012684:Sensory Thresholds / Q000502:physiology*; D015354:Vision, Low / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult