Abstract
Purpose: :
Useful field of view (UFOV) ® studies 1-2 have shown that dividing attention reduced the size of the useful visual field in the elderly, especially in the presence of distracters. Attended field of view (AFOV) refers to the area from which one can extract information when allowed to make eye and head movements. We modeled the AFOV test in order to study divided attention. The purpose of this study is to investigate 1) the effect of age on the AFOV and 2) the impact of a pop out distracter on the AFOV, using a divided attention paradigm.
Methods: :
Nine young adults and 9 seniors participated in two sessions; the first without, and the second with, the pop out distracter. Coeckelbergh et al’s (2004)3 original test was modified by the inclusion of a central task so that divided attention could be studied. The test is a visual search task where participants locate a Landolt ring in a field of 24 distracters (white rings arranged in a radial array at 3 eccentricities_4, 8 and 12 deg) while identifying the direction of an arrow at the central location. The AFOV measure is the time taken to correctly detect the direction of the arrow and the location of the Landolt ring 67% of the time. An individually weighted staircase for the presentation duration was run at 3 locations at each eccentricity. In the 2nd session, the AFOV was measured with the addition of a red pop out distracter (ring) which the participant was instructed to ignore. The sensitivity at each location was calculated as the logarithm of the inverse threshold presentation time and averaged for each eccentricity. A repeated measure ANOVA followed by post hoc comparisons was performed.
Results: :
There was a significant effect of age (p = 0.00) and eccentricity (p = 0.00) but no effect of the pop out distracter. Without the pop out distracter, log sensitivity on the AFOV, for the young and older group was 0.629 ±.06 and 0.147±.06 respectively; with the pop out distracter, it was 0.644 ±.06 and 0.142 ±.06.
Keywords: visual search • aging: visual performance • vision and action