Abstract
Abstract: :
Purpose:To investigate whether functionally relevant features of transient focal attention change as a function of age alone and whether such changes can be counteracted by training. Methods:: Twelve senior subjects (Ss) 60 – 82 years of age and a young control group (ages 22 – 33) with good visual acuity (20/40 or better) participated. Letter recognition performance was tested psychophysically in the near periphery (8 deg eccentricity). They fixated the center of the screen monocularly at 72 cm distance. Any one of 8 radially arranged locations could be cued for 100-300 ms, targets appeared for 100-200 ms immediately after the cue, along with distracters in the uncued locations. Ss indicated verbally, which Sloan letter had appeared. Percent correct responses were plotted for each of the 8 locations. Group differences were tested non-parametrically. Results:1) Senior Ss required longer cue and target durations to perform well (= or >80% in at least 2 locations). 2) At reference durations for cue and target used also in the control group, the compound performance level expressed as the area of the attentional field, seniors showed smaller fields. Both findings were statistically significant with p < 0.05 (Mann-Whitney-U test). Some senior Ss showed improvement of performance through training that allowed reductions of the cue lead time and of target duration. Conclusions:: Age alone diminishes transient attentional performance. Theoretically, this could be caused by reduced numbers of input cells in the M-stream, or by a slowing of performance due to central attentional or cognitive mechanisms. The improvements by training found here suggest that higher mechanisms at least contribute to the age-related decline and cannot be explained exclusively by diminished input from M-neurons.
Keywords: attention • aging • aging: visual performance