Visual Attention Flashcards
What is attention?
The process which results in certain sensory information being selectively processed over other information
What is overt attention?
When you move your eyes from one place to another to focus on a particular object or location
What is covert attention?
When you shift your attention without moving your eyes
What was Cherry’s listening experiment?
Used dichotic listening to present stimuli in the left and right ears
Participants had to focus on one ear and repeat what was being said out loud
What were the results of Cherry’s listening experiment?
Participants could shadow a message in the attended ear but couldn’t report on the other ear
What is dichotic listening?
Presenting different stimuli in the left and right ears
What is shadowing?
Repeating words as they are heard
What is the cocktail party effect?
The ability to focus on one stimulus while filtering out other stimuli
What is Broadbend’s model of attention?
Messages enter a filtering unit that will then let the attended message be detected
What was Michael Posner’s precueing experiment?
Does paying covert attention to a location improve a person’s ability to respond to stimuli presented there?
Used precueing
What is spatial attention?
Attention to a specific location
What is the precueing method?
Participants look at a + in the display
An arrow appears to show which side the stimulus is likely to present on
Press a key as fas as possible when target square was shown
What were the results of Posner’s precueing experiment?
Participants reacted faster in a detection task on valid trials than on invalid trials
Information processing is more effective at the place where attention is directed
What is Anne Teisman’s feature integration theory?
There is a preattentive stage, then a focused attention stage, and then perception
What was Teisman’s experiment?
Participants asked to report identity of black numbers first and then what they saw in each location of the shape
Numbers were correct but not shapes, generally
What is illusory conjunction?
When features of objects combine
What is the preattentive stage?
Features of an object are analyzed rapidly and un-consiously
Features exist independently of each other
What is the focused attention stage?
Attention becomes involved and conscious perception occurs
What is binding?
Individual features are combined
What is visual search?
A procedure where we look for an object among a number of other objects
What is a feature search?
Look for a target with a single feature
What is a conjunction search?
Search for a combination of two or more features
Takes longer than a feature search
What is fixation?
When you are scanning a scene and pause briefly
What is saccadic eye movement?
Rapid, jerky movement from one fixation to the next
What is corollary discharge theory?
Why we don’t see a blur when our eyes move
Associated with 3 signals
What are the 3 signals in corollary discharge theory?
Motor signal
Corollary discharge signal
Image displacement theory
What is the motor signal?
Occurs when a signal to move the eye is sent from the brain to the eye muscles
What is the corollary discharge signal?
A copy of the motor signal, so occurs whenever there is a motor signal
What is the image displacement signal?
Occurs when an image moves across the retina, as happens when movement of the eye causes the image of stationary scene to sweep across the retina
What is the comparator in the corollary discharge theory?
When only a CDS or IDS signal reaches the comparator movement is perceived
When both a CDS and IDS signal reaches the comparator then no movement is perceived
What does corollary discharge help us with?
Keeping our world stationary as our eyes move and deals with the snapshot problem by helping the brain prepare for what is coming next
What is predictive remapping of attention?
Attention begins shifting toward the target just before the eye begins moving toward it
The reason we see a stable, coherent scene
What is visual salience?
Scene regions that are markedly different from their surroundings, whether is colour, contrast, movement, or orientation
What is attentional capture?
Situations in which properties of a stimulus grab attention against one’s will
What is a saliency map?
Reveals regions which are visually different from the rest of the scene
What are scene schemas?
An observer’s knowledge about what is contained in typical scenes
People will spend more time looking at things that are out of place
What is the same-object advantage?
The faster responding that occurs when enhancement spreads within an object
What did Carrasco show?
That attention affected the perceived contrast between the alternating light and dark bars where perceived contrast refers to how different the light and dark bars appear
What does attention to object increase?
Increases activity in specific areas of the brain
What does attention to locations increase?
Increases activity in specific areas of the brain
What does attention shift?
Receptive fields
What is inattentional blindness?
A stimulus that is presented but not attended is not perceived
What is change blindness?
An inability to detect changes in an object or a scene
What is spatial neglect?
Lack of attention to objects in a certain visual field (for example, spatial neglect in the left side)
What is extinction?
provides insight into attentional processing because it suggests that the unawareness of stimuli on the left is caused by competition from the stimuli on right (or vice versa)
What is a selective attention task?
Requires responding to a stimulus while ignoring others
What is a divided attention task?
Requires attending to two or more simultaneous stimuli
What did Green and Bavelier find?
That action video game players consistently performed better on tests of attention and information processing
What do patients with Balint’s syndrome experience more of?
Illusory conjunctions, deficit in locating targets in conjunction search
What is unilateral neglect?
Deficit in awareness of items on one side of space due to brain damage
Cannot reproduce a full image
What are some explanations for unilateral neglect?
Problem in disengaging attention from ipsilateral side; cueing helped reduce spatial bias
Disruption of balance between hemispheres in directing attention; more stimuli on ipsilateral side hampers attention to contralateral items
What was Humphrey’s experiment?
Stimuli was 150 apples, some full, some with gaps on either side
Task was to cross out all of the complete apples in 5 minutes
Participants were people with neglect
Results = egocentric and allocentric neglect
What is egocentric neglect?
Unaware of one side of space
Brain damage was clustered in right anterior cortical regions and subcortical structures
Overlooked complete apples on one side of the page
What is allocentric neglect?
Unaware of one side of objects
Brain damage was in the right posterior cortical regions
People were crossing out apples with a gap on one of the sides
What is brain damage to the right parietal regions common to?
Egocentric and allocentric neglect
What were the implications of Humphrey’s study?
Attention may be either location or object based
Damage to location = egocentric
Damage to object = allocentric
Location = better for static scenes
Object = better for dynamic scenes
What are the implications of inattentional blindness studies?
Not everything presented to our senses is processed
Attention is limited
Visual encoding must be selective or sparse
What is the binding problem?
How are independent, parallel subsystems in vision fused together into a unitary percept?
How does convergence address the binding problem?
Neurons coding for different aspects of an object converge on a single neuron detecting that particular combination
Grandmother cells
No evidence
How does temporal synchrony address the binding problem?
Neurons that signal different aspects of the same object fire in synchrony
Synchronization does not occur if each assembly is triggered by a different stimulus
objects symbolized by population coding
Attention may help synchronize neural firing
What is spatial configuration search?
Target defined by organization of features
eg. find the 5 among 2s
