Why Can a Second Target Vanish Just After the First?

When letters or pictures appear in a rapid stream and you must identify two targets, successfully recognising the first can make the next one surprisingly easy to miss. This is called the attentional blink. It is not a literal blink of the eyes, and it is not simply mind-wandering. In the classic experiments, report accuracy fell when the second target appeared roughly 200 to 500 milliseconds after the first.

The issue is not merely that the display is fast. The first target is being selected, identified and stabilised in working memory. The second may reach the visual system but receive insufficient processing to form a representation that can later be reported. Theories still differ over whether the crucial limit lies in selection, memory consolidation or attentional control. Describing the effect as one fixed bucket of “attention” hides those differences.

The phenomenon also has boundaries. If the two targets appear with no intervening item, the second is sometimes preserved, a pattern known as lag-1 sparing. Task structure, distractors and individual differences all alter the effect. Direct replications published in 2020 broadly reproduced the classic result while also showing that some details were less stable.

In daily life, rapidly checking notifications, instruments or subtitles can also produce the feeling that an item vanished while we were looking. Laboratory findings do not automatically explain every such miss, however. The sound conclusion is narrower: attention is constrained not only across space but across time, and when important items are crowded into a very brief window, the second has less chance of entering reportable awareness.

https://pubmed.ncbi.nlm.nih.gov/1500880/
https://pmc.ncbi.nlm.nih.gov/articles/PMC2915904/
https://pmc.ncbi.nlm.nih.gov/articles/PMC8062350/