Chapter 6: Visual Attention
● Observer is actively involved in creating perceptions through the process of attention
● Attention: process of directing our focus on specific objects/locations and ignoring
others
● The act of attending to an object also enhances its processing
● 2 reasons we pay attention to some things while ignoring others:
○ Bc they are imp. to us
○ Our perceptual system has a limited capacity for processing info
■ This limit helps prevent system overload bc overload ⇒ nothing
processes well
■ Visual system “withdraws from some things in order to deal more
effectively with others” – William James
● Visual scanning: looking from one place to another
○ mechanism for selecting certain things in the env.
○ necessary bc the small fovea on the retina is the only area that creates good
detail vision
Scanning a Scene
● Fixation: aiming the eyes to a particular spot (e.g. pausing to look at one face in a
group pic)
● Saccadic eye movement: rapid movement of the eye from one fixation to another
(e.g. moving your eyes to look at another face in a group pic)
○ Fun Fact: We move our eyes approx. 3 times/sec when freely viewing an
obj./scene
● Overt attention: involves looking directly at the attended obj.
● Covert attention: attention w/o looking; attending to an obj. that is off to the side
What Directs Our Attention?
● 2 processes that cause us to direct our attention to a stimuli:
○ Involuntary processes where a stimuli stands out and catches our attention due
to its physical properties
○ Voluntary processes where our attention is guided by our goals and intentions
, Stimulus Salience
● Stimulus salience: physical properties (color, orientation, contrast, movement) that
make a certain obj./location stand out
● Attentional capture: involuntary shift of attention caused by stimulus salience
○ This is important when it comes to warning us about something dangerous
around us (e.g. explosion, dangerous animal, incoming obj. like speeding car)
● Saliency map: an image that highlights the region on which people's eyes focus first
(due to stimulus salience)
○ Experiments using these maps show that we tend to fixate on high-saliency
areas at first
Selection Based on Cognitive Factors
● Other than saliency, top-down processing determines where we look
○ Meaning of a certain thing can attract a certain person’s attention (scene
scanning varies from person to person)
● Scene schemas: observer’s knowledge about what is contained in a typical scene
(regularities in env.)
○ Associated w/ top-down processing
● Attention being affected by knowledge/scene schemas ⇒ fixating longer on things
that seem out of place in a scene (e.g. printer in kitchen)
Task Demands
● Most tasks require attention to diff places when doing them ⇒ when we look at
specific places is determined by the steps/sequence of actions contained in the task
● Eye movements determined by task
○ Fixate more on objects/areas relevant to task and actions we take related to
task (less fixation, eye movement on irrelevant objects/areas)
● Eye movement usually happens by a fraction of a sec before a motor action (e.g. look
at smth first then you pick it up)
● Experiments show that our attention in a dynamic env. depends on what we learn
about our surroundings (subject and the 3 pedestrians exp.)
● Scene statistics:“the probability of various things occurring in a dynamic
environment”
What Happens When We Attend?
● Attend to smth = become aware of it
● Observer is actively involved in creating perceptions through the process of attention
● Attention: process of directing our focus on specific objects/locations and ignoring
others
● The act of attending to an object also enhances its processing
● 2 reasons we pay attention to some things while ignoring others:
○ Bc they are imp. to us
○ Our perceptual system has a limited capacity for processing info
■ This limit helps prevent system overload bc overload ⇒ nothing
processes well
■ Visual system “withdraws from some things in order to deal more
effectively with others” – William James
● Visual scanning: looking from one place to another
○ mechanism for selecting certain things in the env.
○ necessary bc the small fovea on the retina is the only area that creates good
detail vision
Scanning a Scene
● Fixation: aiming the eyes to a particular spot (e.g. pausing to look at one face in a
group pic)
● Saccadic eye movement: rapid movement of the eye from one fixation to another
(e.g. moving your eyes to look at another face in a group pic)
○ Fun Fact: We move our eyes approx. 3 times/sec when freely viewing an
obj./scene
● Overt attention: involves looking directly at the attended obj.
● Covert attention: attention w/o looking; attending to an obj. that is off to the side
What Directs Our Attention?
● 2 processes that cause us to direct our attention to a stimuli:
○ Involuntary processes where a stimuli stands out and catches our attention due
to its physical properties
○ Voluntary processes where our attention is guided by our goals and intentions
, Stimulus Salience
● Stimulus salience: physical properties (color, orientation, contrast, movement) that
make a certain obj./location stand out
● Attentional capture: involuntary shift of attention caused by stimulus salience
○ This is important when it comes to warning us about something dangerous
around us (e.g. explosion, dangerous animal, incoming obj. like speeding car)
● Saliency map: an image that highlights the region on which people's eyes focus first
(due to stimulus salience)
○ Experiments using these maps show that we tend to fixate on high-saliency
areas at first
Selection Based on Cognitive Factors
● Other than saliency, top-down processing determines where we look
○ Meaning of a certain thing can attract a certain person’s attention (scene
scanning varies from person to person)
● Scene schemas: observer’s knowledge about what is contained in a typical scene
(regularities in env.)
○ Associated w/ top-down processing
● Attention being affected by knowledge/scene schemas ⇒ fixating longer on things
that seem out of place in a scene (e.g. printer in kitchen)
Task Demands
● Most tasks require attention to diff places when doing them ⇒ when we look at
specific places is determined by the steps/sequence of actions contained in the task
● Eye movements determined by task
○ Fixate more on objects/areas relevant to task and actions we take related to
task (less fixation, eye movement on irrelevant objects/areas)
● Eye movement usually happens by a fraction of a sec before a motor action (e.g. look
at smth first then you pick it up)
● Experiments show that our attention in a dynamic env. depends on what we learn
about our surroundings (subject and the 3 pedestrians exp.)
● Scene statistics:“the probability of various things occurring in a dynamic
environment”
What Happens When We Attend?
● Attend to smth = become aware of it
