Fig. 1

(a) Task performance grouped by experimental conditions (Age × Target Predictability × Number of Distractors). In the upper two figures, the Y-axis shows the percentage of identified targets (higher scores mean better performance). The lower figures show in the Y-axis the BIS score, combining accuracy and reaction times (lower scores mean better performance). The left panels represent younger adults and the right represents older adults, with 120 participants per group. The X-axis within each panel indicates the Number of Distractors (12 distractors vs. 24 distractors). Coloured bars denote target predictability: red for predictable targets and grey for random targets; (b) The difference in accuracy between high and low distraction as a function of Age Group. The significant interaction between Number of Distractors × Age Group was driven by greater behavioural costs of adding visual distractors in the older adult group. Values below “0” (marked by the horizontal dashed line) indicate fewer targets found when they appeared among a higher number of distractors. Violin plots show the density and distribution of the difference between the two conditions. Individual dots represent participants; (c) The difference in accuracy between predictable and unpredictable targets as a function of Number of Distractors. The significant interaction between Number of Distractors × Predictability was driven by finding more predictable targets only when the distraction load was high. Values above “0” (marked by the horizontal dashed line) indicate more predictable targets found compared to unpredictable ones. Violin plots show the density and distribution of the difference between the two conditions. Individual dots represent participants.