Effects of perceptual complexity on older and younger adults’ target acquisition performance

The present study evaluated the effects of the three perceptual complexity factors: number of elements, colour variety, and graphical background clutter level, on older and younger adults’ target acquisition time within a computer display. Experiment 1 manipulated the total number of icons, Experiment 2 manipulated the variety of icon colours, and Experiment 3 manipulated the clutter level of the graphical background on the display. In each experiment, 12 older and 12 younger adults were asked to move a cursor to a target icon on the display as quickly and accurately as possible. Target size and distance to the cursor were also manipulated to yield different difficulties of targets. Target acquisition time and Fitts’ law slope were analysed. Results showed that target acquisition time increased for more difficult targets under all the three complexity factors. The amount of increase was more evident for the factors of colour variety and graphical background clutter than for the number of icons. Older participants performed more slowly than younger participants did, particularly for more difficult targets. However, the impact of the three complexity factors on acquisition time appeared to be comparable for both age groups. The results suggest that implementations of colour varieties and graphical backgrounds on interfaces should be restricted, especially when icon acquisition is a common activity involved in interacting with an interface.