- Attentional blink
Attentional blink (AB) is a phenomenon observed in rapid serial visual presentation (RSVP). When presented with a sequence of visual stimuli in rapid succession at the same spatial location on a screen, a participant will often fail to detect a second salient target occurring in succession if it is presented between 200-500ms after the first one. Attentional blink was first described in 1992.cite journal |author=Raymond JE, Shapiro KL, Arnell KM |title=Temporary suppression of visual processing in an RSVP task: an attentional blink? |journal=Journal of experimental psychology. Human perception and performance |volume=18 |issue=3 |pages=849–60 |year=1992 |pmid=1500880 |doi=]
Research
The precise adaptive significance behind the attentional blink is unknown, but it is thought to be a product of a two-stage visual processing system attempting to allocate episodic context to targets. In this two-stage system, all stimuli are processed to some extent by an initial parallel stage, and only salient ones are selected for in-depth processing, in order to make optimum use of limited resources at a late serial stage [ [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=7707027 Chun and Potter (1995) "A two-stage model for multiple target detection in rapid serial visual presentation."] ] .
One curious aspect of attentional blink is that it usually includes "lag 1 sparing", meaning that targets presented "very" close together in time (at "lag 1" or consecutively in the RSVP stream) are not affected by the attentional blink, even though items presented at slightly greater lags are significantly impaired. There is as yet no conclusive explanation for the phenomenon of lag 1 sparing, although it is thought to be related to the first parallel stage of the two-stage system of stimulus selection and processing.
According the LC-NE hypothesis [ [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=16131265 Nieuwenhuis S, Gilzenrat MS, Holmes BD, and Cohen JD. (2005) "The role of the locus coeruleus in mediating the attentional blink: a neurocomputational theory"] ] , when a salient, or meaningful stimulus is presented,
neurons in thelocus coeruleus releasenorepinephrine , a neurotransmitter that benefits the detection of the stimulus. The effect of this release lasts for 100 ms after the salient stimulus is presented and benefits the second target when presented immediately after the first one, accounting for lag 1 sparing. Eventually the neurons in the locus coeruleus enter a refractory period, due to the auto-inhibitory effect of norepinephrine. According to the hypothesis, targets presented during this refractory period cannot trigger a release of norepinephrine, resulting in the attentional blink. The episodic distinctiveness hypothesis of the ST2 model [ [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&list_uids=17227181&cmd=Retrieve Bowman H and Wyble B (Jan 2007) "The simultaneous type, serial token model of temporal attention and working memory." ] ] suggests that the attentional blink reflects a limitation of the visual system attempting to allocate unique episodic contexts to the ephemeral target stimuli presented in RSVP.The attentional blink can be moderated by changes in visual similarity between targets and distractor stimuli, but it can also be affected by "conceptual" similarities, suggesting that stimuli are processed to quite a deep level preconsciously, with much of the resulting information discarded before it reaches consciousness.
The attentional blink is related to, but distinct from the phenomenon of
repetition blindness .Meditation
Studies have suggested that
meditation , particularlyvipassana , may reduce the duration of attentional blink. In an experiment, 17 people received three months of intensive training in meditation. Those 17 along with 23 meditation novices performed an attention task in which they successively picked out two numbers embedded in a series of letters. The novices exhibited attentional blink and missed the second number. In contrast, all the trained meditators consistently picked out both numbers. This indicated meditation practice can improve focus. [ [http://www.sciam.com/print_version.cfm?articleID=434D7C62-E7F2-99DF-37CC9814533B90D7 Biello, David (October 2007) "Searching for God in the Brain" Scientific American] ] [ [http://www.sciam.com/article.cfm?id=meditation-enhances-attention-video Scientific American video blog] ]References
External links
* [http://www.psych.ucsb.edu/labs/giesbrecht/index.html The Laboratory for Attention, Brain, and Behavior] , lead by Dr. Barry Giesbrecht, has published a number of studies addressing the attentional blink.
* [http://www.rit.edu/~gssp400/Blink/blinkinstr.html Theory and instructions for attentional blink]
* [http://develintel.blogspot.com/2006/02/minds-eye-models-of-attentional-blink.html Computational Models of the Attentional Blink]
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