Source: Laboratory of Jonathan Flombaum—Johns Hopkins University
In order for recognition of a certain stimulus to take place, visual attention needs to be directed towards said stimulus. To the earliest parts of the visual system, objects are not objects, they are collections of visual features-lines, corners, changes in texture, color, and light. Attention is the resource that is necessary for later processing in order to recognize what a given bundle of features adds up to. This makes attention a central focus of research. One especially important set of questions concerns how people sustain attention, that is, the extent to which they can continuously maintain a focus of attention from moment-to-moment. It is now known that sustained attention takes great effort. When attention needs to be focused very rapidly on something that is moving or changing very quickly, the effort involved causes a momentary lapse in attention once it is disengaged. This kind of lapse in attention is called an attentional blink. It is like the brain blinks for a moment, shutting down attention for a rest. Stimuli that appear during an attentional blink will not be perceived.
In 1992, a group of researchers devised a paradigm to study the attentional blink, and the paradigm has come to be known by the same name.1 It demonstrates some of the challenges to maintaining focused attention. This video demonstrates how to implement the attentional blink paradigm in order to study sustained visual attention.
1. Equipment
2. Stimulus and experiment design
Figure 1: The basics of rapid serial visual presentation (RSVP). A series of images is shown in rapid succession, in this case, lowercase letters each remaining for only 50 ms before becoming replaced by the subsequent letter.
Figure 2: Methods for the attentional blink. A ready screen is followed by an RSVP stream consisting mainly of letters, 30 images in total. Embedded among the letters are two numbers. The first number appears anywhere between the 8th and the 20th positions in the stream. The position of the second number is called a lag and defined relative to the appearance of the first number such that following the first immediately is called lag 1, the next position lag 2, and so on. The experiment consists of 30 trials at each of lags 1-6.
Figure 3: Organization of a data output table for an attentional blink experiment. Each row corresponds to a trial of the experiment. The important parameters to record are the position of the first number in the stream (a value between 8 and 20), the lag until the second number (a value between 1 and 6), the identity of the two numbers shown, and the responses given by the participant at the end of the trial.
3. Running the experiment
4. Analyzing Results
Figure 4: Populated data output for an attentional blink experiment. The columns Accuracy 1 and Accuracy 2 report whether the response entered by a participant matched the actual identities of the number presented during each trial. 1 indicates a correct response, and 0 indicates an incorrect response.
Graph average response accuracy for the first number, along with response accuracy for the second number as a function of lag position. Figure 5 shows an example.
Figure 5: Results of an attentional blink experiment. As shown, participants are generally able to report the first number in a sequence with very high accuracy, here about 0.97. When a second number appears immediately, performance is not as good, but still very high-a phenomenon called lag 1 sparing. In the second and third lag positions, performance tends to be very poor however. This is called the attentional blink, the idea being that attention is mustered to process the first number rapidly, and then becomes momentarily unavailable-like blinking one's eyes- before it can be engaged again to recognize a second number. The results suggest that heavily focused attention can be sustained, but only with brief interruptions following bouts of intensive processing.
The graph can be generated for each participant, or averaged across a group of participants. As shown in the figure, the pattern of performance is that participants tend to be very accurate reporting the identity of the first number in each trial. This demonstrates that even though the number appears very briefly, in an unpredictable location, and embedded between letters, focused attention can support detailed processing and recognition. Immediately following numbers are processed accurately as well, as shown by the relatively high performance for lag 1 numbers. This is known as lag 1 sparing. It is thought that as the focused attention remains engaged during this time, the rapid appearance of the next number allows it to be processed. However, at lags 2 and 3, performance is considerably impaired. This is the phenomenon that is known as the attentional blink.
The idea is that following the processing of the first number, attention becomes temporarily disengaged-like blinking one's eyes. Remember, the numbers shown in lags 2 and 3 last for all of 50 ms each, not a very long time. They just happen to appear during a brief period in which attention disengages. It quickly re-engages however, to support rapidly improving performance during for lags 4, 5, and 6. Taken together these results demonstrate the power and limitations of sustained visual attention. Attention can be sustained to find and identify brief and unpredictably positioned stimuli-numbers. Intensive processing is followed by a brief respite, temporarily limiting the ability to recognize objects.
Like many other laboratory tasks for studying attention, the attentional blink has become a common tool in studies of brain damage, as well as in studies that use neuroimaging techniques to investigate the brain areas involved in controlling and coordinating attention.
The attentional blink paradigm has also been used to investigate the kinds of things that may capture attention automatically, and even how anxiety and other mental health problems may cause diverted attention. These studies use the same paradigm just described, only with pictures of real-world images instead of letters. A participant's task would be to detect any image that is rotated in an unusual position, reporting at the end of the trial whether the rotated image was an indoor or an outdoor scene. Figure 6A shows an example of this basic paradigm, and Figure 6B then shows how the paradigm is used to ask whether something automatically captures attention.
Figure 6. Methods for the emotion-induced attentional blink. Panel A shows a general RSVP procedure with photographic images. The task is to detect the image in the stream that is rotated (called the target), and at the end of the trial, to report whether that image was an indoor or an outdoor scene. Panel B shows how these methods are used to produce an emotion-induced attentional blink. Prior to the appearance of the target, an emotional-inducer is shown, here a spider, an object about which many people express fear and anxiety and which tends to grab attention. The target is then shown at lag 2 relative to the emotional-inducer. Although the inducer is task-irrelevant, if it is sufficiently attention-grabbing, it will produce an attentional blink, and participants will have difficulty detecting the rotated target, evidenced by inaccurate indoor/outdoor reports.
In Figure 6B, a spider is shown in the RSVP stream prior to the target. In fact, the target is shown at lag 2 relative to the spider image. The spider is not task relevant, but fear of spiders is common. If the visual system is tuned to automatically detect and process spiders, then the presence of that image in the stream would produce an attentional blink. Indeed, that is what has been found-spiders, snakes, and other threatening images automatically capture attention, producing an emotion-induced attentional blink.
Researchers have also used this paradigm to investigate differences between people with severe phobias, and those with just the usual antipathy towards spiders. In this case, the paradigm is reversed. A target is presented and a spider is shown at lag 2. Is the spider seen, or is it rendered invisible because of the attentional blink? For most people, perception of the spider is blocked by the attentional blink. But for individuals with arachnophobia, the spider is seen, even in lag positions that should suffer from a blink. This suggests that a phobia causes certain stimuli to have a very strong pull on attention, even when attention would otherwise be disengaged.
Skip to...
Videos from this collection:
Now Playing
Sensation and Perception
15.8K Views
Sensation and Perception
11.1K Views
Sensation and Perception
17.3K Views
Sensation and Perception
11.8K Views
Sensation and Perception
6.9K Views
Sensation and Perception
18.3K Views
Sensation and Perception
17.4K Views
Sensation and Perception
13.2K Views
Sensation and Perception
14.9K Views
Sensation and Perception
5.7K Views
Sensation and Perception
15.5K Views
Sensation and Perception
16.0K Views
Sensation and Perception
15.3K Views
Sensation and Perception
24.3K Views
Sensation and Perception
6.4K Views
Copyright © 2025 MyJoVE Corporation. All rights reserved