2011年6月7日 星期二

Attention and Awareness Aren't The Same

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Press Release (Association for Psychological Science)

Paying attention to something and being aware of it seems like the same thing -they both involve somehow knowing the thing is there. However, a new study, which will be published in an upcoming issue of Psychological Science, a journal of the Association for Psychological Science, finds that these are actually separate; your brain can pay attention to something without you being aware that it's there.

"We wanted to ask, can things attract your attention even when you don't see them at all?" says Po-Jang Hsieh, of Duke-NUS Graduate Medical School in Singapore and MIT. He co-wrote the study with Jaron T. Colas and Nancy Kanwisher of MIT. Usually, when people pay attention to something, they also become aware of it; in fact, many psychologists assume these two concepts are inextricably linked. But more evidence has suggested that's not the case.

To test this, Hsieh and his colleagues came up with an experiment that used the phenomenon called "visual pop-out." They set each participant up with a display that showed a different video to each eye. One eye was shown colorful, shifting patterns; all awareness went to that eye, because that's the way the brain works. The other eye was shown a pattern of shapes that didn't move. Most were green, but one was red. Then subjects were tested to see what part of the screen their attention had gone to. The researchers found that people's attention went to that red shape – even though they had no idea they'd seen it at all.

In another experiment, the researchers found that if people were distracted with a demanding task, the red shape didn't attract attention unconsciously anymore. So people need a little brain power to pay attention to something even if they aren't aware of it, Hsieh and his colleagues concluded.

Hsieh suggests that this could have evolved as a survival mechanism. It might have been useful for an early human to be able to notice and process something unusual on the savanna without even being aware of it, for example. "We need to be able to direct attention to objects of potential interest even before we have become aware of those objects," he says.

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For more information about this study, please contact: Po-Jang Hsieh (Brain & Consciousness Lab) at hsieh.pj@gmail.com.

The APS journal Psychological Science is the highest ranked empirical journal in psychology. For a copy of the article "Unconscious pop-out: Attentional capture by unseen feature singletons only when top-down attention is available" and access to other Psychological Science research findings, please contact Divya Menon at 202-293-9300 or dmenon@psychologicalscience.org.

5 意見:

yuan 提到...

Could you give us a clear functional(or operational) definition of "attention" you mentioned in this study? It seems that attention is an implicit process according to the study.

Brown 提到...

Attention is defined as enhanced visual sensitivity at the cued location.

yuan 提到...

How about priming effect? When priming affects the speed of processing, does it mean that it also involves attention?

... 提到...

I have the same comments as the ones that yuan proposed. Stimuli could be processed without involvement of "attention". The "red dot" is processed does not guarantee "attention" per se is involved.

This makes me think of "Blindsight": (from Wikipedia) "Blindsight is a phenomenon in which people who are perceptually blind in a certain area of their visual field demonstrate some response to visual stimuli. In Type 1 blindsight subjects have no awareness whatsoever of any stimuli, but yet are able to predict, at levels significantly above chance, aspects of a visual stimulus, such as location, or type of movement, often in a forced-response or guessing situation."

Blindsight subjects have no awareness, but yet are able to predict some aspects of a visual stimulus. Can we conclude that, although blindsight subjects are unaware of visual stimuli, they can rely on their "attention" to predict some aspects of a visual stimulus?

However, this is still an interesting paper, inspiring us to think about the possibility of levels (or kinds) of "attention".

Many papers used similar paradigm to induce "unconsciousness". Below is one example:
http://sheng-lab.psych.umn.edu/pdf_files/Jiang-etal-PNAS-06.pdf

Brown 提到...

If you check figure 1 in this paper (https://sites.google.com/site/pojanghsieh/publication/paper23.popout.pdf?attredirects=0), you can see that during the suppression period, there are many green balls and one red ball in the suppressed eye. You can argue that subliminal priming occurs because all the balls are processed unconsciously. I have no objection with that claim. But what I'm trying to show is the the red ball is processed differently than the green balls. More specifically, the red ball is processed "more deeply" to the degree that it enhances visual sensitivity at that location. Why is the red ball processed more deeply than the green balls here? I don't think priming can explain it. My interpretation is that the red ball (the oddball) attracts attention automatically/unconsciously.

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