9. Visual Attention

Question 1

Attention

Answer 1

mental processes for seeking out and focusing on relevant (visual) stimuli, which are consequently processed to a greater extent (at the expense of other stimuli)

The amount of information processed is limited because out sensory and motor systems are limited

Visual scenes are scanned to take in different parts; measured with camera-based eye-trackers, our saccades and fixations

Question 2

sensory systems are limited

Answer 2

Limited Sensory Range:
Each sensory system is tuned to a specific range of stimuli. For example, the human eye can only detect light within the visible spectrum (~400-700 nm) We cannot perceive ultraviolet or infrared light

Resolution and Acuity:
Sensory acuity varies across modalities. In vision, for instance, our acuity is highest in the fovea (central vision) but decreases significantly in the periphery

Sensory Adaptation:

Our sensory systems adapt to constant stimuli, reducing responsiveness over time. For example, we become less sensitive to continuous smells or sounds, which can limit the detection of persistent environmental changes.

e.g., visual fixations, size of foveal gaze

Question 3

motor systems are limited

Answer 3

Motor Precision:
While we can execute many complex movements, motor precision is limited by factors such as muscle coordination and neural control. Fine motor skills (like threading a needle) require precise control, which is not always possible in all parts of the body (e.g., the legs).

Reaction Time:
There is a delay between sensory input, decision-making, and motor output. Our reaction time can be slowed by the complexity of a task or age-related factors, limiting how quickly we can respond to fast-moving stimuli.

fatigue:
Muscles and neural circuits controlling movement experience fatigue over time, reducing strength, accuracy, and endurance

e.g., movements planned/words spoken sequentially

Question 4

saccades

Answer 4

are rapid, jerky eye movements that shift the gaze from one point to another. They allow the eyes to quickly reposition to focus on different objects or areas in the visual field. Saccades occur during tasks like reading or scanning a scene.

• saccadic suppression: attenuation in some spatial frequencies during saccade
  ▸ neither motion of the eye/motion blur nor gap in perception is detected
  ▸ begins before eye movement (thus, is not an optical effect)

Question 5

fixations

Answer 5

moments when the eyes are relatively still and focused on a particular point. During a fixation, visual information is processed, allowing us to gather detailed information about the object or area we’re looking at.

• about 3 fixations/second
• fixation locations may be determined by:
  ▸ visual salience: colour, contrast, orientation (bottom-up process)

▸ picture meaning/observer knowledge: what do you expect to see? (top-down process)

▸ task demands: what are you being asked to do?

Question 6

overt attention

Answer 6

directing foveal gaze (and attention) to a stimulus

Question 7

covert attention

Answer 7

directing attention to a stimulus in peripheral vision

• attention can be used to select stimuli independent of fixation

Question 8

Helmholtz and Covert attention

Answer 8

• put matrix of letters on wall, with fixation cross in the centre
• fixated on cross and turned lights off
• directed his attention (not his eyes) to a certain location, then briefly illuminated room with a spark
• could perceive letters in attended region, but not in other regions
• attention can be used to select stimuli independent of fixation

Question 9

selective attention task

Answer 9

requires responding to a stimulus while ignoring others

e.g., reading a textbook while trying to ignore interruptions

Question 10

divided attention task

Answer 10

requires attending to two or more simultaneous stimuli

e.g., driving, drinking a coffee, and talking on cell phone at the same time

Question 11

what do videogames teach us about attention?

Answer 11

Green and Bavelier (2003):

• found that action video game players consistently performed better on tests of attention and information processing
• attention is a skill that can be honed with practice

action video games enhance attentional processing?

• had non-gamers play Medal of Honor: Allied Assault™ game 1 hour/day for 10 days: visual attention skills improve
• less improvement in control group who played tetris™

Question 12

components of attention

Answer 12

Michael Posner, Nissen, & Ogden (1978):

• attention viewed as a spotlight: can focus on certain locations

1. disengaging attention from current location
2. moving attention to new location
3. engaging attention in new location

Question 13

precueing (or Posner spatial cueing) task

Answer 13

a cognitive experiment designed to study attention and how it influences the processing of visual information. In the task, participants focus on a central point on a screen and are briefly shown a cue (an arrow or flash) that suggests where a target will likely appear (left or right side). After the cue, the target appears, and the participant responds as quickly as possible.

There are 3 types of conditions:
-neutral
-Valid cues: Correctly predict the target’s location.
-Invalid cues: Direct attention to the wrong location.

Findings:
Faster reaction times occur with valid cues because attention is already directed to the correct location.
Slower reaction times occur with invalid cues due to the need to shift attention away from the cued location.

Question 14

is attention a top-down or bottom-up process?

Answer 14

attention is not only exogenous or “stimulus-driven” (bottom-up), but also endogenous or “goal-directed” (top-down)

Question 15

Balint’s syndrome

Answer 15

patients experience more illusory conjunctions; deficit in locating targets in conjunction search

Simultanagnosia: Inability to perceive multiple objects at once, meaning the person can only focus on one object in their visual field at a time.

• supports the idea that attention can be object-based
• syndrome may be due to inability to shift attention among objects

Question 16

Unilateral neglect (a.k.a. hemispatial neglect)

Answer 16

• deficit in awareness of items on one side of space, due to brain damage
• damage results in neglect of objects (or parts of objects) in the contralesional visual field

e.g., may eat food from just one side of a plate, shave/make-up one side of face, fail to dress one half of their body, or copy only half of a drawing:

• patients often unaware of this deficit
• typically due to damage in right posterior parietal cortex, critical to attention and selection
• explanations:
• problem in disengaging attention from ipsilateral (same) side; cueing (directing attention) helped reduce spatial biases
• disruption of balance between hemispheres in directing attention; more stimuli on ipsilateral side hampers attention to contralateral (opposite side) items:

Question 17

egocentric neglect

Answer 17

unaware of one side of space:

▸ 11 people overlooked complete apples on the left side of the page; 2 people missed complete apples on the right side

▸ brain damage was clustered in right anterior cortical regions, and subcortical structures

• brain damage to certain right parietal regions was common to both groups

Question 18

allocentric neglect

Answer 18

unaware of one side of objects:

▸ 8 people crossed out apples with gaps on their left side; 2 people crossed out apples with gaps on their right side

▸ brain damage was in right posterior cortical regions

• brain damage to certain right parietal regions was common to both groups

Question 19

is attention location based or object based?

Answer 19

• attention may be either location-based or object-based
• different parts of the brain process different kinds of attention
• damage to location-based system produces egocentric neglect, damage to object-based system results in allocentric neglect
• location-based processing is better suited to static scenes, whereas object-based processing works well for following a moving object in dynamic scenes

Question 20

inattentional blindness

Answer 20

stimulus that is presented, but is not attended, is not perceived (a.k.a. “looked-but-didn’t-see” problem)

there is no conscious perception of the visual world without attention to it

Question 21

change blindness

Answer 21

an inability to detect changes in an object or a scene

Implications:

• not everything presented to our senses is processed
• attention is limited
• visual encoding must be selective or “sparse”

Levin & Simons (1997):
- observers told to “pay close attention” to a video of a conversation
- only 1 of 10 observers noticed any changes

Simons & Levin (1998): the door study
- only half of the observers noticed a change in the stranger
- changes may be local or global, fast or slow
- however, people do notice changed sex, race, or social group

Question 22

The Binding Problem

Answer 22

• how are the independent, parallel subsystems in vision (form, motion, colour, etc.) fused together into a unitary percept?
• how are the parts of an object unified into a whole?

Question 23

Convergence

Answer 23

Hubel & Wiesel (1977):

• neurons coding for different aspects of an object (e.g., color, form, etc.) converge on a single neuron detecting that particular combination
• implies we have a neuron for every object we can recognize (“grandmother cell” theory)
• problems: little evidence; we can recognize too many objects; cannot account for perception of novel objects

Question 24

temporal synchrony theory

Answer 24

Engel et al. (1991

• assemblies of interconnected neurons, each signaling different aspects of the same object, fire in synchrony
• however, if neurons are triggered by different stimuli, there is no synchronization
• evidence: crosscorrelograms of activity from cat cortical neurons with similar receptive fields
• one long moving bar: bursts of neural activity are strongly correlated
• two small bars moving in the same direction: synchronization is weaker
• two bars moving in opposite directions: no synchronization
• attention may play a role in synchronizing activity (Gross et al., 2004)

Question 25

Feature Integration Theory. FIT

Answer 25

(Treisman, 1986; Treisman & Gelade, 1980):

• attention must be focused on particular stimulus attributes or parts in space to construct a representation or percept

there are the pre attentive and focused attention tages

Question 26

preattentive stage FIT

Answer 26

• rapid, automatic decomposition of stimulus into a number of basic properties (“primitives”)
• processing is in parallel

Question 27

focused attention stage FIT

Answer 27

• serial (sequential) process
• spatial location selected
• primitives existing at this spot are combined

e.g., redness and X-ness combined into red X-ness

• combination object is called object file only exists temporarily to be examined by focused attention

Question 28

Visual search:

Answer 28

primitives determined via visual search experiments:

• task: find target among nontargets/“distractors”
• observers asked whether a display contains target
• RT (and errors) are recorded
• types of visual search: feature. conjugation, spatial configuration

Question 29

feature search

Answer 29

target defined by one basic property/primitive

e.g., find a green 2 among red 2s

Question 30

conjunction search

Answer 30

“and” search

target defined by a combination of two or more basic properties/primitives

e.g., find a green 5 among green and red 2s, and red 5s

Question 31

spatial configuration search

Answer 31

target defined by organization of features

e.g., find a 5 among 2s

Question 32

pop-out

Answer 32

time needed to find the target is very short/constant

• lots of slow, serial processing not required
• RT not influenced by the number of distractors
• primitives cause pop-out in feature search:

e.g., colour, brightness, orientation, length, curvature, etc.

Question 33

pros and cons to FIT

Answer 33

☑ explains binding (combining primitives) at the psychological (not neural) level, and accounts for the role of attention

☑ evidence: illusory conjunctions: when attention is overtaxed, primitives may be incorrectly combined
e.g., red Xs, blue Os: you may perceive a blue X

e.g., Stroop effect (1935): shows attentional inhibition of automatic cognitive processes

☒ with practice, conjunction search may become automatic/parallel (should not be possible)

☒ is attention necessary for perception?

How can we be aware of anything that we are not attending to?

How can we shift our attention to a new stimulus, if we aren’t aware that it exists yet?

Cases of brain damage (e.g., blindsight) can reveal perception without awareness.

Question 34

are the eyes like cameras?

Answer 34

eyes are not like cameras; visual data not processed like watching a movie

Question 35

What is the difference between selective attention and divided attention? What function does attention serve in perception?

Answer 35

Selective attention involves focusing on one specific stimulus or task while ignoring others. It allows us to prioritize important information.

Divided attention refers to the ability to attend to multiple stimuli or tasks simultaneously. It often reduces the efficiency of processing compared to selective attention.

Attention serves to filter out irrelevant information, enhance the processing of relevant stimuli, and improve perceptual clarity and decision-making.

Question 36

How did Posner and his colleagues study covert attention? Describe their experiment and its results. What do these results tell us about covert attention?

Answer 36

Posner and colleagues studied covert attention (shifting attention without moving the eyes) using the Posner spatial cueing task. Participants were asked to focus on a central point while cues indicated where a target might appear. Results showed that participants responded faster when a valid cue correctly predicted the target’s location, even without eye movements.

These findings demonstrated that attention can be directed to a location without overt movement, improving the speed and accuracy of processing stimuli in that area.

Question 37

What is attentional capture? Describe an experiment reviewed in the textbook that examined features of attentional capture.

Answer 37

Attentional capture refers to the automatic redirection of attention toward a salient or unexpected stimulus, even when it is not relevant to the current task. An experiment might involve participants focusing on a task when suddenly a bright or novel stimulus appears, causing them to shift attention involuntarily.

An example from the textbook would involve showing participants a series of objects and inserting a highly contrasting or moving object. These features often capture attention, even when they are irrelevant.

Question 38

What is the difference between change blindness and inattentional blindness? Describe an example of each. Why are they considered errors of attention?

Answer 38

Change blindness: Failure to notice changes in a visual scene, often because the change occurs during a brief disruption (e.g., a door passing in front of two people). Example: A person doesn’t notice that a new object was added to a room after briefly looking away.

Inattentional blindness: Failure to notice an unexpected object because attention is focused elsewhere (e.g., the famous “gorilla in the basketball game” experiment). Example: A person fails to see a pedestrian while focusing on their phone.

Both are considered errors of attention because they occur when attentional resources are either insufficiently directed or overburdened, leading to missed information.

Question 39

What is feature integration theory? How does it explain feature searches and conjunction searches?

Answer 39

Feature integration theory (FIT), proposed by Anne Treisman, suggests that attention is required to bind different features (e.g., color, shape) together to form a coherent perception of objects.

Feature search: Involves detecting a single, distinct feature (e.g., finding a red object among green ones), which is fast and effortless.

Conjunction search: Involves combining multiple features (e.g., finding a red circle among red squares and green circles), requiring attention and thus taking longer.

Question 40

What is the rapid serial visual presentation (RSVP) paradigm? How is it conducted in the lab, and what aspect of attention does it measure?

Answer 40

The RSVP paradigm presents a rapid stream of visual stimuli (e.g., letters or images) at the same location, one after the other. Participants are asked to identify specific targets within the sequence. This method measures temporal attention, especially the ability to focus on brief, quickly presented information.

It is often used to study the attentional blink, where people are less likely to detect a second target if it appears soon after the first.

Question 41

Orienting Attention Network

Answer 41

a neural system, located primarily in the parietal lobe, that allows us to engage in visual search and direct our visual attention to different locations in visual space

Function: This network is responsible for the ability to shift attention to different locations or stimuli in space. It helps direct attention to a specific location (spatial attention), enabling the detection of new stimuli or monitoring of environmental changes.

Brain areas: Primarily located in the parietal lobe, particularly in the superior parietal lobe, and involves the frontal eye fields and subcortical structures like the superior colliculus.

Aspect of attention served: It controls spatial attention and is important for tasks like visual searches and detecting changes in the environment.

Question 42

Executive Attention Network

Answer 42

a system that focuses on attention by the inhibition of habitual responses and acts as the top-down control of attention; found in the frontal lobe

Function: This network handles higher-order attention control and cognitive processes such as conflict resolution, decision-making, and inhibiting inappropriate habitual responses and top-down control. It is essential for managing attention in complex tasks, multitasking, and maintaining focus amid distractions.

Brain areas: It involves the prefrontal cortex (particularly the anterior cingulate cortex and dorsolateral prefrontal cortex) and is linked to areas in the frontal and parietal lobes.
Aspect of attention served: It regulates cognitive control, focusing attention on relevant tasks while suppressing irrelevant distractions. It is key for tasks that require sustained and selective attention.

Question 43

What is unilateral neglect? What are its symptoms? What kind of brain damage causes it?

Answer 43

Unilateral neglect is a condition where a person fails to attend to one side of their visual field, often ignoring objects or stimuli on that side.

Symptoms: Patients may only eat food on one side of their plate or only dress one side of their body.

Cause: It is typically caused by damage to the right parietal lobe, leading to neglect of the left visual field.

Question 44

What is binocular rivalry? How is it measured, and what principles of awareness does it demonstrate?

Answer 44

Binocular rivalry occurs when each eye is presented with a different image, and perception alternates between the two images instead of combining them. It is measured by presenting distinct images to each eye and asking participants to report which one they perceive at any given moment.

It demonstrates that visual awareness is not stable and that our perception can fluctuate between competing stimuli based on attention and neural processes.

Question 45

What is blindsight? Describe the deficits and preserved function in the patient T.N. What is typically thought of as the neurological basis for the preserved function in blindsight?

Answer 45

Blindsight refers to the phenomenon where individuals with damage to their primary visual cortex (V1) cannot consciously see but can still respond to visual stimuli (e.g., detecting motion or light).

In the case of patient T.N., despite being cortically blind, he could still navigate around obstacles without conscious awareness of seeing them. The preserved function is thought to arise from alternative visual pathways (e.g., through the superior colliculus) that bypass the damaged primary visual cortex, allowing for unconscious visual processing.

Question 46

How does our understanding of visual attention help us explain the safety issues associated with cell phone use during driving?

Answer 46

Cell phone use while driving divides attention between the road and the phone, leading to inattentional blindness and slower reaction times. Even hands-free phone use can reduce a driver’s ability to notice important visual information, such as pedestrians or changing traffic signals, increasing the likelihood of accidents. Understanding these limits on attention underscores the importance of reducing distractions to ensure safety on the road.

Question 47

attentional blink

Answer 47

the tendency to respond less reliably or not at all to the second appearance of a target in an RSVP task when the second target occurs within 500 ms of the first target

Question 48

Attentional capture

Answer 48

the process whereby a salient stimulus causes us to shift attention to that stimulus

Question 49

Rapid serial visual presentation (RSVP) paradigm

Answer 49

a method of studying attention in which a series of stimuli appear rapidly in time at the same point in visual space

Question 50

Repetition blindness

Answer 50

the failure to detect the second target in an RSVP task when the second target is identical to the first one; like attentional blink, it occurs when the second target is presented 500 ms or less after the first target

Question 51

Simultagnosia

Answer 51

a deficit in perceiving more than one object at a time

Question 52

Stimulus onset asynchrony

Answer 52

the difference in time between the occurrence of one stimulus and the occurrence of another, in this case, the cue and the target

Question 53

Stimulus salience

Answer 53

refers to the features of objects in the environment that attract our attention