Age-Related Preservation of Top-Down Control Over Distraction in Visual Search

Abstract

Visual search studies have demonstrated that older adults can have preserved or even increased top-down control over distraction. However, the results are mixed as to the extent of this age-related preservation. The present experiment assesses group differences in younger and older adults during visual search, with a task featuring two conditions offering varying degrees of top-down control over distraction. After controlling for generalized slowing, the analyses revealed that the age groups were equally capable of utilizing top-down control to minimize distraction. Furthermore, for both age groups, the distraction effect was manifested in a sustained manner across the reaction time distribution.

This research was supported by research grants R37 AG002163, R01 AG011622, and training grant T32 AG000029 from the National Institute on Aging, and research grant R03 MH080849 from the National Institute on Mental Health. The authors are grateful to Susanne M. Harris for administrative assistance.

Notes

Note. n = 24 per age group. Vocabulary = raw score (maximum of 70) on the Wechsler Adult Intelligence Scale-Revised (Wechsler, 1981); Visual Acuity = Landolt C acuity measure from Freiburg Visual Acuity and Contrast Test (FRACT) (Bach, 1996), with a log MAR of 0 equivalent to 20/20 acuity and lower values indicating better acuity. Color Vision = score (out of 14) on the Dvorine color plates (Dvorine, 1963). Means in the same row that do not share subscripts differ by t-test at p < .05.

¹Compatibility effects between the symbols (+, =) located within the targets and distractors (i.e., color singletons) were also analyzed, sorting trials into compatible trials (same symbol for target and distractor), incompatible trials (different symbols for target and distractor), and no-distraction trials. An ANOVA on zRT found a significant effect for compatibility, F(1, 46) = 107.50, p < .0001, and a Condition × Compatibility interaction, F(2, 96) = 22.69, p < .0001. Bonferroni paired comparisons, t(48) > 2.84, p < .05, indicated that, in the sometimes condition, responses on both compatible and incompatible trials were slower than on the no-distraction trials, but the two compatibility conditions did not differ significantly. In the never condition, in contrast, zRT for both compatibility types was again higher than for no-distraction trials, but an additional slowing was evident when the target and color singleton were response-incompatible. There were no age group main or interactive effects for compatibility.

²We conducted additional ANOVAs with the neighboring positions as 1) only distraction (color singleton nontarget) trials, and 2) only no-distraction (no color singleton) trials. The results for each were similar to those obtained when averaging across these two trial types: 1) no age group main effects, 2) no Age Group × Position interactions, 3) a strong position main effect (p < .0001). The distraction and non-distraction trials contributed roughly equivalently to the main analyses, with non-distraction trials comprising 56% at position −2, 49% at position −1, 55% at position +1, and 62% at position +2, similarly for the two age groups.

³Because RT generally increases with display size, the increase in RT with percentile bin may simply reflect the influence of display size. To rule out this possibility, these same analyses were run separately by display size, and yielded similar results: 1) older adults yielding consistently higher distraction effect compared to younger adults, and 2) increasing distraction effect with increasing bin. Thus, the binned analyses are not equivalent to display size effects but represent dynamics inherent across them.