bounce occurred in the 200 msec preceding the end of the
trial. The 200-msec time period is comparable to that of
the effect of explicit cues in conventional attentional cuing
studies, where processing benefits are typically seen for
stimuli presented 80–300 msec after cuing (Nakayama &
Mackeben, 1989; Posner, 1980). When the boundary walls
were visible in Experiment 2, the effect of these bounces
disappeared, suggesting that it was the unexpected or unexplained
nature of the direction changes that attracted
attention.