Visual search — 1 VISUAL SEARCH ACROSS THE LIFE SPAN

The focus of this study was to evaluate the gains and losses in visual search performance across the lifespan in a representative sample of 298 individuals ranging from 6 to 89 years of age. Adopting a lifespan developmental perspective, two general resource theories were considered: cognitive speed and inhibitory control. Participants searched computer displays to indicate the presence or absence of a single target among 2, 8, or 14 stimuli. Distractors differed either by a single feature (color) or the combination of two features (color, shape) in feature and conjunction search conditions, respectively. For target-present trials, target eccentricity was also systematically varied. In line with previous findings, search performance was substantially slower early and late in life, compared to early adulthood. Furthermore, the age gradients were more pronounced in conjunction than in feature search conditions. More interestingly, developmental and aging trends were distinctly asymmetrical in terms of sensitivity to different experimental manipulations: children's search performance was particularly affected by the mere presence of distractors; whereas in late life, search performance was particularly impaired on target-absent trials, and with increasing numbers of distractors. In contrast, all age groups were uniformly affected by manipulations of target eccentricity, and consistently produced search slopes of less than 10 ms/item during feature search conditions. We interpret the observed asymmetries between child development and aging with respect to lifespan theories of cognitive and attentional development.