Attention and Perception - 11

Attention as a Gateway to Perceptual Experience

Attention is a gateway to perceptual experience.
Perceptual experience arises when attending to stimuli.
Without attention, visual stimuli might be missed.
Attention isn't sufficient for perception; changes can be missed even while attending.
The attention of others provides cues to their thoughts, goals, and intentions.
Benefits of attention include increased sensitivity to specific objects.
Costs of attention include missing important changes; attention alone is insufficient for perception.

Limitations of Attention

Distracting flashes or rapid eye movements (saccades) can prevent seeing items, despite attention.
Slow changes may be missed despite attention.

Attention Disorders: Neglect

Neglect is a condition resulting from damage to the right dorsal parietal cortex.
It causes individuals to ignore half of the visual world, typically the left side.

Following Attention to Understand Others

Observing where others attend helps in understanding their actions.

Benefits of Attention: Sensitivity

Double Stimulus Example: Face and House.
Attending to faces enhances the ability to identify female faces.
Attention boosts behavioral sensitivity.
Attending to houses enhances the ability to distinguish architectural styles.
Attention can be focused on one object type even in double exposures.
This focused attention boosts behavioral sensitivity, making it easier and faster to spot the relevant object class.

Brain Activity and Attention

Brain scans show enhanced blood flow to relevant brain areas when attention is directed to specific object types.
The fusiform face area (FFA) shows increased activity when attending to faces.
The parahippocampal place area (PPA) is active when looking at houses and environments.
Attending to houses boosts PPA activity, while FFA activity decreases.

Inattentional Blindness Demonstration

Experiment: Counting passes made by a white team in a video.
Participants often miss a person in a gorilla suit walking through the scene because their attention is focused on counting passes.

Real-World Implications: Eyewitness Testimony

Inattentional blindness has implications for eyewitness testimony.
If not attending to the right place, important details may be missed.

Radiological Example

Radiologists looking for cancerous growths (white blobs) in lung images may miss a gorilla inserted into the image.
This demonstrates that when the search is focused on one type of object, dramatic abnormalities can be missed.

Change Blindness

Even when told to attend to a specific area, changes can be missed.
Film Example: A person changes identities and clothing, but observers often miss this.

Factors Affecting Change Detection

Attention is necessary but not always sufficient to notice changes.
Rapid eye movements (saccades) can distract from seeing changes.
Visual information may be suppressed during eye movements.
Experiment: People providing directions fail to notice when the person they are talking to changes identity after a door passes between them.
Interruptions in the scene disrupt the ability to detect change.

Flashes and Change Detection

Flashes within an image decrease the chance of seeing other changes.
Experiment: A horizontal bar jumps at the same time as flashes, but the flashes distract observers from seeing it.
Experiment: Participants looking for driving-related signals miss that a white line changes from crosshatch to solid due to distracting flashes.

Gradual Changes

Very gradual changes are difficult to spot, even when attending to them.
Experiment: The color of a woman's clothing changes slowly from blue to pink, but it is hard to notice.
Experiment: A rock gradually appears in a scene, but it is difficult to spot unless one is looking at the right place.

Change Blindness Summary

Change blindness occurs when we fail to notice an item changing.
Reasons:
- Changes happen very slowly and gradually.
- Irrelevant flashes or saccadic eye movements occur during the transition.
- Movement itself can suppress the ability to see change.
$Movement suppressing change detection$ : A scintillating pattern of dots changing color is easily seen until the whole array moves, making the color changes difficult to detect.

Pathology of Attention: Neglect

Attention control problems occur after damage to the right parietal cortex.
Damage can lead to hemispatial neglect, where a person ignores part of the world (usually the left side).
Example: A patient asked to cross off stars only marks those on the right side of the page.
Line bisection task: Patients with neglect bisect lines far to the right, as if the left side is underestimated or doesn't exist.

Salience and Neglect

Making objects on the left side salient can sometimes help patients with neglect attend to that side.

Classic Figures Illustrated

Drawings by patients with neglect often depict only the right side of objects (e.g., a flower, a cube).
Self-portrait of an artist with right parietal stroke shows unrecognizable features on the left side of the face.

Spatial Neglect Summary

Spatial neglect arises from damage to the right temporal or parietal cortex.
It leads to the inability to attend to the left side of space and objects.
Symptoms include ignoring items on the left, bisecting lines with a bias to the right, and drawing only the right side of objects.

Anosognosia

Anosognosia is a condition where a patient is unaware of their neurological problem.
Patients with neglect may deny they have neglect, unaware they are only attending to half of the world.
In the case of hemiplegia, the paralyzed arm is not recognized, and the individual fails to recognize that they can't use the arm.
Stroke in the visual cortex can cause blindness, but additional damage in the parietal cortex can stop the patient from realizing they're blind.
Patients with Anton's syndrome are blind but don't realize it and may confabulate what they can see.
Anosognosia occurs through damage to parts of the brain where neglect occurs.

Thought Experiment: Neglect and Memory

Does neglect affect imagined memories in the same way it affects vision?
Example: Asking a patient with neglect to imagine walking through Saint Mary's quadrangle and describe what they see.
From one direction, they might only describe the right side of the scene.
If asked to imagine the scene from the opposite direction, would they describe the opposite side?
The answer can be found in reference to neuropsychologists working in Milan, asking people to imagine a famous piazza from different perspectives.
Does neglect affect memory or just vision.

Attention and Face Perception

Cells in the brain respond to the sight of faces, often coding the head view.
Some cells are tuned to the front view, while others are tuned to the profile.
These cells may signal face identity or a more basic quality: the direction of attention.
A cell tuned to the face field but not the profile view may be coding the attention direction of the person being viewed.
The cell is sensitive to head view and also sensitive to gaze direction.
Gazing to the left can suppress the response that would be to the normal face.
About two-thirds of cells that respond to the head view also code gaze direction.
Another cell may respond to the head when down, indicating attention is down.
Looking elsewhere in the environment doesn't activate the cell.

Coding Attention Direction

Cells may code head view and gaze direction to indicate where someone else is attending.
Cells can also code body direction.
A bipedal posture with a horizontal gaze indicates attention is probably about horizontal.
A quadrupedal posture possibly with the person attending down indicates attention is down.
Cells respond to different body postures consistent with attention in a particular direction.
There is evidence that cells coding the sight of faces are really coding the attention direction.
Two-thirds of the cells that respond to the face are also sensitive to gaze direction and body view.
The importance of gaze: wrong gaze inhibits the correct view, suggesting that gaze is a strong indicator of attention.
Cells responding to faces may actually be coding the attention direction of other individuals.

Utility of Gaze Direction

Gaze direction serves as a cue to attention.
Autistic individuals and individuals with high shyness may process gaze differently.
They are less sensitive to certain cues from gaze.

Gaze Following

In clinical interviews, normally individuals will follow the attention of a caregiver.
Example: A child with Down's syndrome looks to the left when the clinician looks to the left.
An autistic individual may show less spontaneous redirection of attention to follow the clinician's attention.
Paradoxically, autistic individuals show good gaze geometry; they can work out where the gaze is directed but don't necessarily use it as a cue to where others are attending.

Social Implications of Attention

There are many situations where using the direction of attention of another individual is beneficial.
Chimpanzees may avoid claiming food rewards in full view of a dominant chimp to avoid conflict.
Scrub jays re-cache food if they have been overseen to prevent it from being pilfered.
The Sally-Anne task defines what others know or believe.
Attention can be used to understand what other people know and believe.
Knowledge can be inferred from attention direction.

Social Learning

Attention direction is critical in social learning.
Monkeys learn to fear snakes by observing other monkeys reacting with fear to snakes.
The observing monkeys must look to see what the other monkeys are interacting with and where they are looking.
If an individual labels an object (e.g., a computer mouse), attending to that object provides a cue to which object in the world is being labeled.
Children acquire language by following the attention direction of someone using language.
They learn that this is a computer mouse because they see people attending to it when describing that object with the object name.

Summary

Attention is good; it boosts spatial sensitivity, but it can blind us to whole, unexpected, and unattended events.
Attention is not sufficient for visual experience; items may be missed due to distraction or slow changes.
Attention disorders, such as hemispatial neglect, follow parietal damage and lead to half of the world being ignored.
Following attention is good for understanding other people's minds and what they're doing.
Spontaneous attention following seems to be reduced in autistic individuals.
Following someone else's attention is useful for understanding their intentions and for social learning of language.