Figure 1.

Example of trial structure in Experiment 1. For each trial a specific random luminance sequence (e.g., sequence A) was presented four times. Each luminance sequence lasted 3.125 s and consisted of a disc with randomly changing luminance at 160 Hz. Sequences were separated by an ISI of 3 s. Response sequences, which contained an embedded square image (1 s duration, random onset time within sequence), were distributed at random points in-between trials throughout the experiment. Participants were requested to press a key after each sequence if they noticed a square.