Age-related differences in saccadic indices of top-down guidance via short-term memory during visual search

Aging has  been  associated  with significant  declines  in  the  speed  and  accuracy  of visual search. These effects have been attributed partly to low-level (bottom-up) factors including  reductions  in  sensory  acuity  and  general  processing  speed.  Aging  is  also associated  with  changes  in  top-down  attentional  control,  but  the  impact  of  these  on search is less well understood. The current study investigated age-related differences in top-down attentional control by comparing the speed and accuracy of saccadic sampling in  the  presence  and  absence  of  top-down  information  about  target  color  in  young  (YA) and older (OA) observers. Displays contained an equal number of red and blue Landholt stimuli.   Targets   were   distinguished   from  distractors   by   a   unique   orientation   and observers reported the direction of the target’s gap on each trial. Single-target  cues signaled the color of the target with 100% validity. Dual-target cues indicated the target could   be   present   in   either   colored  subgroup.   The   results   revealed   reliable   group differences in the benefits associated with top-down information on single-compared to dual-target cues. On single-target searches, OA made significantly more saccades than YA to  stimuli  in  the  uncued  color  subset.  Single-target  cues  also  produced  a  smaller advantage  in  the  time  taken  to  fixate  the  target  in  OA  compared  to  YA.  These  results support  an  age-related decline in observers’ use of top-down  information  to  restrict sequences of saccades to a task-relevant subset of objects during visual search.