Abstract
Abstract: :
Background: Transient attention (TA) can be attracted by a physical exogenous cue indicating the location where TA is to be deployed (i.e. by "explicit" cuing). TA can also be attracted without such a cue, only by the salience of its different appearance compared with distracters (i.e. "implicit" cuing). Purpose: To investigate whether implicitly cued TA shares features with explicitly cued TA and whether it changes as a function of age. Methods: 20 subjects (Ss) participated in this study. They belonged to one of 3 age groups: < 35, 50–59, and 60 and older, the age range was 22 to 91 years. The Ss fixated a central mark on a monitor screen. At an unpredictable time, a ring of 8 stimuli appeared for 67 to 133 ms, of which 7 were distracters and one was a letter target. Eccentricity was always 8 degrees. Ss were asked to verbally identify the target. A minimum of 30 trials were performed for each position in the ring. Vector diagrams were constructed to indicate performance level for each position. Results: 1. Performance varied greatly depending on target location (range = 6% to 94 % correct). 2. The size of the "performance field" was a function of target duration. 3. In most Ss, the spatial characteristics of the field for implicitly cued TA resembles those of the field for explicitly cued TA. 4. The size of the performance field, indicating overall performance level, as well as the mean % correct responses, relate inversely to Ss age, but only when comparing the young Ss with the oldest group. The difference was statistically significant with p < 0.05. Some Ss belonging to any of the 3 age groups showed improvement of their implicit TA performance with practice (240 trials). Conclusions: It is likely that the mechanism underlying the attraction of transient attention by implicit cuing is the same as that underlying the attraction of TA with explicit cuing. Rapid evaluation of target salience diminishes with age past 60 years.
Keywords: aging: visual performance • discrimination