Chapter 6: Visual Attention Flashcards
Define Selective Attention
Focusing on specific objects and ignoring others
- Important because of bombarding information the sensory systems have to make sense of
How does the structure of the retina help with selective attention?
There’s high detail vision in the fovea + cortical magnification
There’s a constant blurry periphery (but brain fills in details)
Define Overt Attention
Attention involving directly looking at objects
Define Covert Attention
Attention without moving eyes
Define Saccades
Small quick eye movements used to scan a scene
Define Fixation
Pauses between saccades, used to gather information
Define Stimulus Salience
Characteristics of the environment that stand out because of physical properties (high contrast, colour, orientation)
- People tend to focus first on high salient regions, then meaningful regions (except in natural environments)
What is a Saliency Map?
A map showing fixations are related to meaning and saliency
Define Scene Schema
Observer’s knowledge about the type of scene can influence the order of fixation
What are 2 findings that support the idea of Scene Schema?
- Shinoda: observers notice stop signs more at an intersection (45%)
- Vo+Henderson: observers fixate longer on objects that don’t belong (a printer in a kitchen)
Define Spatial Attention
Attention to specific locations
Explain Posner’s experiment involving spatial attention
Observers had to look at a fixation point, then press a button when a target stimuli was presented in the side (reaction time measured)
- Result: reaction time was faster when given a cue of which side the target would be on
- Finding: information processing is more efficient where attention is directed
Explain Egly’s experiment regarding spatial attention
Observers had to viet 2 raft angles, there were cues as to where targets may appear, and task was to press button when target appeared
- Finding: fastest reaction time at targeted position
- Finding: “enhancement” effect for non-target in same target rectangle
- *check notes for drawing**
Explain O’Craven’s experiment involving the FFA and PPA activity
Participants observed a double exposure of a house and face, while being monitored with an fMRI
- Result: while attending to the face, enhanced activity in FFA
- Result: while attending to the house, enhanced activity in the PPA
What is Inattentional Blindness?
A stimulus is not perceived even when the person is looking directly at it
Explain Simons + Chabris’ experiment involving inattentional blindness
Observers were asked to count the number of passes in a short film of teams passing a ball, a gorilla passes through
- Result: 46% of observers do not notice the gorilla
Define Change Blindness
Difficulty detecting changes in a scene
Explain Rensik’s experiment involving change blindness
Two photos were shown. In the second, a coke bottle is replaced with a water bottle
- Result: only 11% of people detected a change (if told there would be changes)
- Finding: if important information that draws your attention (motion) is missing, it’s difficult to see the change
Can you have perception without direct, focused attention?
Yes
Explain Li’s experiment involving 3 tasks
Observers performed 1/3 tasks:
- Central task: determine whether letters flashed on center of the screen are the same
- Peripheral task: determine whether the image contained an animal or not
- Dual task: do the same as peripheral and determine colour of a disk
- Result: dual task had larger effect on colour tasks
- Result: better at attending to animal rather colour
How long does it take to identify the gender of a face?
150ms
What do attention maps show?
Directing to a specific area of space activates a specific area of the brain
Define Task Irrelevant Stimuli
Stimuli that do not provide information relevant to the task
Explain the Load Theory of Attention
There is a capacity for attention
- Perceptual capacity
- Perceptual load: requirement of task (high load vs low load)
Explain Foster + Lavie’s experiment involving the load theory of attention
Reaction times of various tasks (easy-difficult) are recorded
- Result: there is greater impact on easy load if there is distraction
- Explanation: with hard tasks, already hits capacity so there’s less of an affect
What is Binding?
A process where physical features (colour, form) are combined to create perception of an object
Binding is necessary because of the many areas of the brain involved in processing all aspects of an object
What is the Binding Problem?
We have to group very different information (motion, colour, form) to perceive objects as single units
What is the Feature Integration Theory?
Attention has major role in solving binding problem
Define Illusionary Conjunctions
Features associated with one object that are incorrectly associated with another
(Supports feature integration theory)
Explain Treisman + Gelade’s experiment involving feature integration theory
Observers were shown 4 shapes and 2 numbers simultaneously, then were asked to report figures
- Result: Observers mixed up properties of shapes, unless asked to attend to shapes’ colours
- Finding: there is a Preattentive Stage where features are separate, focusing attention causes the Focused Attention Stage
Who is Patient R.M. (feature integration theory)?
Parietal lobe damage caused Balient syndrome (where he couldn’t focus on objects individually, making illusionary conjunctions)
How often to incorrect associations of features occur (when not asked to focus on a target object)?
18% of the time
What is a Conjunction Search?
Finding a target with 2 or more physical features
Explain Klin’s experiment involving the effects of autism on attention
Autistic and non-autistic participants watched films while their eye movements were recorded
- Result: autistic observers looked at socially irrelevant stimuli while non-autistic observers focused on the eyes of actors and the direction actors pointed at
- Finding: where autistic individuals pay attention in social situations may lead to perceiving the world differently
Explain Pelphrey’s experiment involving the effects of autism on attention
Participants watched a cartoon character (while STS was monitored) that:
- Moved his eyes toward a checkboard (congruent)
- Moved eyes away (incongruent)
- Result: activation of STS in non-autistic individuals was higher for incongruent conditions while it was higher in both conditions for autistic individuals
- Finding: autistic individuals cannot read intentions of others
