주의적 깜박임
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Overview
출처: 조나단 플롬바움 연구소 -존스 홉킨스 대학
특정 자극이 일어날 수 있도록, 시각적 주의는 말했다 자극을 향해 지시 할 필요가있다. 시각적 시스템의 초기 부분에서 개체는 개체가 아니며 시각적 특징 선, 모서리, 텍스처, 색상 및 빛의 변화입니다. 관심있는 것은 주어진 기능 번들이 추가하는 것을 인식하기 위해 나중에 처리하는 데 필요한 리소스입니다. 이것은 주의 연구의 중심 초점. 특히 중요한 질문 중 하나는 사람들이 관심을 유지하는 방법, 즉 순간부터 순간까지 지속적으로 관심의 초점을 유지할 수있는 정도에 관한 것입니다. 이제 지속적인 관심은 큰 노력이 필요하다는 것으로 알려져 있습니다. 매우 빠르게 움직이거나 변화하는 것에 주의를 기울여야 할 때, 관련된 노력은 일단 분리되면 주의를 기울여야 합니다. 이러한 종류의 주의 상실은 주의적 깜박이라고 합니다. 그것은 뇌가 잠시 깜박처럼, 휴식에 대한 관심을 종료. 주의 깜박임 중에 나타나는 자극은 인식되지 않습니다.
1992년, 한 연구자 그룹이 주의적 깜박임을 연구하기 위해 패러다임을 고안했으며 패러다임은 같은 이름으로 알려지게 되었습니다. 1 집중적인 주의를 유지하는 데 따르는 몇 가지 과제를 보여줍니다. 이 비디오는 지속적인 시각적 주의를 연구하기 위해 주의적 깜박임 패러다임을 구현하는 방법을 보여줍니다.
Procedure
Results
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.
Applications and Summary
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.
References
- Raymond, J. E., Shapiro, K. L., & Arnell, K. M. (1992). Temporary suppression of visual processing in an RSVP task: An attentional blink?. Journal of Experimental Psychology: Human Perception and Performance, 18(3), 849
Transcript
Processing information in a rapidly changing environment is demanding, and visual attention is necessary for object recognition to occur.
For example, to recognize how a group of features comprises an object, like this football, visual attention is required, and sustaining it takes considerable effort.
In dynamic situations where items move rapidly—like a football and players on the field during a game—the attentional effort involved causes a momentary lapse in attention once it is disengaged, such as when the quarterback is looking for a receiver.
This lapse is referred to as an attentional blink—as if the brain blinks for a moment, shutting down attention for a rest—in which stimuli, such as an opponent, are not perceived.
Based on the methods pioneered by Raymond, Shapiro and Arnell in 1992, this video demonstrates how to implement the phenomenon of Attentional Blink by discussing the steps required to design the stimuli and execute the paradigm, as well as how to analyze the data and interpret the results describing the accuracy of responses across trials with varying levels of attentional engagement.
In this experiment, a series of images, such as large black lower case letters and numbers in Helvetica font, are presented for 50 ms one after the other—an experimental procedure called Rapid Serial Visual Presentation, RSVP for short.
Each trial is programmed to display 30 characters in total, whereby two of the images are different numbers between 1 and 9.
The first is randomly placed somewhere between the eighth and twentieth RSVP position, while the second digit is randomly inserted in a spot immediately after the first number, to six places after it. This spacing is called the lag position, which can range from 1 to 6.
Over the course of the experiment, there are 180 trials, 30 at each of the 6 lag positions.
After each trial, participants are asked to report the numbers, in the order that they appeared, during the RSVP. The dependent variable is recorded as the number of correct responses across lag positions.
The logic behind the paradigm is that the first number will grab the participant’s attention, leading to a very high accuracy in naming the first ones. However, depending on the lag position, performance is expected to vary when reporting the second number.
If it appears immediately after the first, performance should still be very high—a concept called lag 1 sparing.
Accuracy should be affected most dramatically when the second number is in the second and third lag positions—because of the attentional blink phenomenon—and accuracy will be less affected at the later lag positions, those that occur after the short attentional blink window.
Before the experiment, set up the program to generate an output spreadsheet that reports all of the relevant data for subsequent analysis, including the trial number, the position of the first digit in the RSVP stream and the lag, the true identity of the first and second numbers, and the responses given.
To begin, greet the participant in the lab and guide them into the experimental room. Have them sit comfortably in front of the computer, with their chair back approximately 60 cm away.
Now, explain the task instructions: The screen will display the word “Ready?”until the space bar is pressed, after which a series of letters and numbers will immediately and rapidly appear.
Direct the participant to indicate what numbers they saw by pressing the corresponding keys in the same order they saw them. Remind them that if they are not sure what numbers they saw, to just guess.
After answering any questions, leave the room and allow them to complete the 30 trials at all lag positions, for a total of 180. When they are finished, thank them for taking part in the experiment.
To begin data analysis, open the spreadsheet with the data output from the experiment. Add two columns, named ‘Accuracy 1’ and ‘Accuracy 2’, to indicate whether the participant correctly identified the number in each position.
For each trial, in the column labeled ‘Accuracy 1’, indicate whether or not they identified the first number correctly by placing a 1 or incorrectly by assigning a 0. Duplicate this for the column labeled ‘Accuracy 2’.
Next graph the mean accuracy across all trials for the first, along with the averages for the second numbers reported—’Accuracy 2’—by lag positions.
Notice that the response for the first number—’Accuracy 1’—was very high, which 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.
As predicted, when the second number immediately followed the first, accuracy remained high due to lag 1 sparing. Thus, focused attention triggered by the first number remains engaged, allowing for the capture of the second number.
However, for lag positions 2 and 3, mean accuracy values decreased dramatically, reflecting the phenomenon of attentional blink. That is, after processing the first number, attention becomes temporarily disengaged, thereby reducing processing and recognition.
Though, the attentional blink did not last long, as shown by the improved performance for lag positions 4, 5, and 6.
Now that you are familiar with the phenomenon, let’s look at how the paradigm is used to investigate the basic limitations of visual attention in more detail, including the kinds of things that may capture it automatically, and even how anxiety and other mental health problems may divert it.
In a similar RSVP task using photographs, participants were asked to identify a target image—one that was rotated in an unusual position. For example, an upside-down room was included as the target, and participants reported if it was an indoor or an outdoor scene.
In some trials, researchers added a picture of a spider to the stream in a position preceding the target. They hypothesized that this might automatically capture attention because of the fear it induces. In this case, they reasoned that it should produce an attentional blink—leading the rotated target to be missed.
Indeed, participants responded inaccurately when a spider preceded the target, demonstrating that fear-inducing objects can automatically capture attention and produce attentional blinks.
Researchers have also used the same paradigm to investigate differences between people with severe phobias and those with just a typical dislike of spiders.
In this instance, the task is reversed: the rotated room is shown beforehand, presenting the spider in the lag 2 position. For most participants then, the perception of the spider is blocked by the attentional blink.
Interestingly, individuals with severe arachnophobia did not show an attentional blink, as they reported seeing the spider—suggesting that at times, emotional stimuli have a very strong pull on attention, when it would otherwise be disengaged.
You’ve just watched JoVE’s introduction to the attentional blink. Now you should have a good understanding of how to design and execute an attention-engagement task, as well as analyze and assess the results.
Thanks for watching!