The ‘attentional blink’ is a famous phenomenon within cognitive science. Researchers were able to generate a temporary blindness in their participants, where letters were being presented right in front of their eyes without them noticing. This effect helps us better understand how attention works and may prove useful in studying different disorders.
What is the Attentional Blink?
The attentional blink was first named in the early 90s by researchers studying temporal attention, or “attention in time”. Researchers commonly used search tasks (think ‘Where’s Waldo’) to better understand how we use spatial attention to find targets, so to study attention in time, they used a task that presented letters very briefly at the center of the screen to see if people could pick out targets of interest.
The task was rather simple: a bunch of black letters were presented one after another really quickly. Within this stream of letters, participants had to watch for two different items: a white letter and the letter ‘X’. The white letter was presented on every trial, but the X was only there 50% of the time. The X could appear any time after the white letter, so sometimes it would be the next letter to appear, and sometimes it was six letters after the white target. After all the letters were presented, participants had to report the identity of the white letter and whether they saw the X.
In the above case, the participant would report that ‘P’ was the white letter, and that yes, there was an X.
Here’s a slowed-down example of a couple trials in GIF form:
Participants are very capable of focusing their attention to catch the targets; if you just ask people to report whether the X was there without bothering with the white letter, they will be correct 9+ times out of 10. When trying to spot both the white letter and the X, if there was over 700ms (or about 6 or 7 letters) between these two targets, this stellar accuracy was maintained. However, when the X was presented within half a second of the white letter, their accuracy dropped to around 50%, which meant they were completely guessing and didn’t have a clue whether the X was presented or not. This effect is what we call the attentional blink, since participants were performing as if their eyes were closed.
Why is this the case?
Well, attention is what we in the world of cognition call a ‘limited capacity mechanism’. This means that there is only so much attention that can be used at any given time. In this task, people are focused on identifying the white letter, which is quite demanding since it’s only on the screen for a tenth of a second and within a stream of other distracting letters. After this, your attention needs time to replenish and reset for the new task of spotting the X. It’s during this recovery period of half a second that you are blind to changes in your environment.
There is one interesting exception to the above rule: when the X immediately follows the white letter (within a tenth of a second), participants are much better than chance at identifying whether the X was present. Scientists believe this happens because the X gets to piggyback on the attention that was meant to be focused on the white letter, and it sneaks its way into your consciousness.
How can this be used to study attention in different groups?
Researchers have been using the attentional blink to understand the effects different disorders have on attention, like schizophrenia and multiple sclerosis. By observing how these disorders change the size and duration of the blink, scientists can better identify the type of attention deficits present and come up with more targeted treatments. Researchers have also observed that meditators have a smaller attentional blink, which indicates greater attentional control.