Four-dot masking produces the attentional blink.

When two target stimuli (T1 and T2) are presented sequentially within half a second of each other, identification accuracy is often poor for T2. This phenomenon, known as attentional blink (AB), can be observed generally only if the stimulus terminating the presentation of T2 acts as an interruption mask. Recent evidence suggests that even four small dots surrounding a target item can exert masking effects, provided the target onset occurs at an unattended spatial location. In order to test whether an AB could be observed under conditions of four-dot masking of T2, five rapid serial visual presentation streams of letters were synchronously displayed on each trial of the present experiment. T1 and T2 were digits presented at unpredictable locations and unpredictable temporal intervals. T2 was followed by either a blank field, a letter, or four-dots. No AB was observed when T2 was not masked, but robust and equally sized ABs were observed when T2 was followed by both the letter mask and the four-dots.