Abstract
Activities like grocery shopping often unfold in a sequential order, allowing people to acquire sequence learning. Using the serial reaction time (SRT) task, previous studies have shown that people respond more quickly to a repeated rather than a random sequence of locations. However, sequence learning was disrupted in visual search tasks involving distractors, suggesting that certain visual properties may constrain sequence learning. Here, we tested the dependence of sequence learning on apparent motion and visual clutter. Experiment 1 tested the hypothesis that sequence learning depended on participants perceiving the object as moving from one location to another. If so, learning should be reduced when the stimulus conditions do not support apparent motion. Participants pressed a button to report the location of a circle on each trial in two conditions: a high-contrast condition involving a white circle presented against a black background, and an equiluminant condition involving a pink circle presented against a green background. In both conditions, the circle’s location followed a 12-trial sequence that repeated 30 times. Although apparent motion was weakened in the equiluminant condition, participants acquired robust SRT learning in both conditions. Experiment 2 tested the hypothesis that visual clutter interfered with sequence learning. Participants pressed a button to report a person’s location against three types of background: (i) a blank background; (ii) a grocery store picture that remained constant across trials; and (iii) different grocery stores that varied randomly from trial to trial. In all conditions, participants acquired SRT learning of the person’s location across a 12-trial sequence. These experiments demonstrated that sequence learning was robust. It did not depend on apparent motion and was insensitive to visual clutter. The lack of sequence learning in previous search tasks likely reflects distractor processing rather than a failure to learn from equiluminant or cluttered displays.