Attention
• A classic definition:Everyone knows what attention is. It is the taking possession by
the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others…
William James
James’ Attention• “Taking possession of the mind…”
– Attention has a voluntary aspect
• “…of one out of what seem several simultaneous possible objects or trains of thought…”– Attentional capacity is limited– Attention involves a process of selection– Attention is not only focusing but also ignoring
• “…withdrawal from some things in order to deal effectively with others…”– Ignoring is an active process
Early Research Demonstrating Limited Capacity
• E.C. Cherry (1953)• Selective auditory
attention• “Dichotic listening”
procedure• Subjects given different
inputs to each ear• Subject asked to report
input from one ear first then other ear second
• Subjects unable to report unattended channel
Early Research Demonstrating Selection and Inhibition:The Cocktail Party Effect
• A relevant conversation can be attended to in spite of a welter of background conversation…
• But attention can be captured by some meaningful stimulus event occurs in that background
What is attention??
• Traditional information processing views: Based on limits to simultaneous processing.
• Mechanisms exist to filter, gate, select or inhibit.
• Prevailing view for years: Broadbent Bottleneck
• A basic conversion from massive parallel input to a limited or serial processing mode.
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal• Frontal
Neurochemistry!!• Ach• NA• DA
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal• Frontal
Neurochemistry!!• Ach• NA• DA
The Early Selection Model fell, due to its inability to account for many experimental results.
The answer to this: “Late Selection”
• All stimuli processed to a “semantic” level, then selected on the basis of task relevance
Problem with Information Processing View: It doesn’t account for the brain.
Sequel to information processing:
• Hi degree of parallel processing
• Flexible allocation of resources
• Attention interacts with motor output.
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal (neglect)• Frontal
Neurochemistry!!• Ach• NA• DA
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal (neglect, cued orienting, biased competition)
• Frontal
Neurochemistry!!• Ach
• NA
• DA
Early Research in the field of perception had already addressed a more “modern view”
• Hermann von Helmholtz• Electric spark randomly
illuminated part of the screen
• Centrally-fixed gaze• Moved attention to a part
of the screen• Found he could discern
letters in the illuminated part if his attention was fixed there PRIOR to the spark
Discovered “covert attention”
Along came Posner and Boies
• Attention is not a unitary phenomenon.
• Alertness or Readiness to take in information (concentration, vigilence)
• Selective Attention – search a display or an environment for a particular target.
Selective Attention Was Divided a Fluid Process With Three Components
• Engage
• Disengage
• Move– A Visuospatial Attention Task Was devised to
test this hypothesis and begin to map attention on to “visual” areas of the brain.
The Typical Result is:A “benefit” of valid cuing (faster reaction times and more accurate responding) and a “cost” of invalid cuing (slower reaction times and less accurate responding).
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal• Frontal
Neurochemistry!!• ACh• NA• DA
Selective lesions of the cholinergic neurons in the basalforebrain of rats produces the same increased cost – What does this say for Posner’s Theory???
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal (neglect, cued orienting, biased competition)
• Frontal
Neurochemistry!!• Ach
• NA
• DA
James’ Attention• “Taking possession of the mind…”
– Attention has a voluntary aspect
• “…of one out of what seem several simultaneous possible objects or trains of thought…”– Attentional capacity is limited– Attention involves a process of selection– Attention is not only focusing but also ignoring
• “…withdrawal from some things in order to deal effectively with others…”– Ignoring is an active process
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal• Frontal
Neurochemistry!!• Ach• NA• DA
Classic Task Examining Inhibition of Classic Task Examining Inhibition of attention: Negative priming (Tipper) taskattention: Negative priming (Tipper) task
• One picture is superimposed upon another.– One is printed in red the other in green ink.– Participants are told to name one (always red
ink) and to ignore the other (green ink).– Before each trial a prime is presented briefly.– Naming a red trumpet is affected when the
prime is a red kite and a green trumpet (ignored) compared to when the prime is a red kite and a red anchor.
– Ignored information must be actively suppressed.
• The Stroop effect in psychology is a demonstration of interference. When color words such as blue, green, red, etc. are printed in various colors and someone is asked to say the color the words are printed in rather than reading the words, it is very difficult to do, at least at first. The effect is named after its discover, John Ridley Stroop, who wrote an article on it in 1935.
Stroop effect- another classic Test of Attentional Inhibition OR Impaired
Response Inhibition
Green
Yellow
Red
Purple
Blue
Red
Black
Yellow
Orange
Blue
Purple
Red
Green
Black
Blue
Yellow
Green
Red
Purple
Blue
Blue
Brown
Blue
Red
Green
Green
Yellow
Red
Yellow
Orange
Blue
Red
Green
Yellow
Black
Yellow
Orange
Red
Purple
Blue
Purple
Red
Green
Black
Blue
Yellow
Green
Red
Purple
Blue
Green
Yellow
Red
Yellow
Orange
Blue
Brown
Blue
Red
Green
Who has trouble with Negative Priming and Stroop??
• Patients with Frontal Lobe Damage
• Patients with Frontal Dementia
• Children
• Chronically Stressed Patients
The brain and attention
• Processing models (stone ages)• Biological theories
Cortex!!• Parietal• Frontal
Neurochemistry!!• Ach• NA• DA
A principled model of attention?
“ we have shown that the orientation of attention - specifically, the disengagement or movement of attention- is mediated by acetylcholine”
(Phillips et al, 2000)
Rescorla-Wagner Rule
Association update rule: w w + αδuw : weight (association)
α : learning rateu : stimulus
Prediction error: δ = r - vr : actual reward
v : expected reward
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