Holistic Face Processing and Prosopagnosia

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Questions and Answers

What condition is characterized by the inability to recognize familiar faces while being able to see individual facial features?

Prosopagnosia (correct)

Visual Agnosia

Object Agnosia

Facial Synesthesia

Which symptom distinguishes object agnosia from prosopagnosia?

Difficulty assembling facial features

Inability to recognize faces

Reliance on memory for recognition (correct)

Inability to recognize context

What brain damage can lead to prosopagnosia?

Damage to emotional processing areas

Damage to language centers

Damage to visual cortices (correct)

Damage to motor cortex

Which of the following is an example of voluntary attention?

Choosing to focus on a book while in a crowded place Signup and view all the answers

What characteristic is common in both prosopagnosia and object agnosia?

Recognition impairment Signup and view all the answers

What is a common feature of object agnosia regarding object recognition?

Visual recognition impairment without context Signup and view all the answers

Which aspect of attention involves being drawn to noticeable stimuli in the environment?

Reflexive attention Signup and view all the answers

Patient CK's condition reflects which key concept regarding face and object recognition?

Separation of visual recognition systems may exist. Signup and view all the answers

What is holistic processing in the context of face recognition?

Recognizing faces by perceiving them as a whole. Signup and view all the answers

What happens to holistic processing when faces are inverted?

It hinders recognition capabilities. Signup and view all the answers

What is prosopagnosia?

A condition where a person cannot recognize familiar faces. Signup and view all the answers

What type of attention refers to focusing on a location without moving the eyes?

Covert attention Signup and view all the answers

Which area of the brain is primarily associated with acquired prosopagnosia?

Fusiform area in the right hemisphere. Signup and view all the answers

Which of the following statements about face recognition in individuals with prosopagnosia is true?

They have difficulty recognizing their own reflection. Signup and view all the answers

Which of the following best describes the concept of Helmholtz's Spotlight Theory?

Attention acts like a spotlight, illuminating specific areas. Signup and view all the answers

How do face cells in the monkey inferior temporal lobe function?

They are specialized cells that respond primarily to faces. Signup and view all the answers

What is the main difference between exogenous and endogenous orienting of attention?

Exogenous is automatic; endogenous is voluntary. Signup and view all the answers

Which of the following components are part of the attentional control network?

Fronto-parietal network Signup and view all the answers

What is an example of a challenge that individuals with prosopagnosia might face?

Recognizing familiar faces without context. Signup and view all the answers

In the Posner Spatial Cueing Paradigm, what characterizes a VALID cue?

A correctly cued, attended location Signup and view all the answers

What is the composite effect in face recognition?

Merging two faces to create the appearance of a third person. Signup and view all the answers

How does attention influence processing speed according to the document?

Attention speeds up processing and improves accuracy. Signup and view all the answers

What time frame is noted for the attentional effect during a spatial cueing task?

70-100ms after the stimulus Signup and view all the answers

What distinguishes covert attention from overt attention?

Covert attention occurs without eye or head movements; overt involves them. Signup and view all the answers

What primarily causes baseline shifts in the retinotopic cortex?

Spatial attention Signup and view all the answers

Which metaphor best describes the mechanism of attention that focuses on specific areas or objects?

Attention as a Spotlight Signup and view all the answers

In conjunction search, what is the primary reason for slower target detection?

Requires careful analysis of each item Signup and view all the answers

What phenomenon occurs when individuals fail to notice salient events, such as an unexpected object in their visual field?

Inattentional blindness Signup and view all the answers

What is the result of contralateral neglect in patients with right temporal/parietal lobe damage?

Failure to detect information on the left side Signup and view all the answers

Which of the following best characterizes Broadbent's filtering theory regarding attention?

Selection of relevant information takes place early Signup and view all the answers

What does the phenomenon of change blindness typically demonstrate?

Difficulty noticing major changes in visual scenes Signup and view all the answers

In tasks requiring feature integration, which areas of the brain are primarily involved?

Superior Parietal Cortex and Superior Frontal Cortex Signup and view all the answers

What effect does monocular deprivation have on neural development in infants?

Neurons respond only to the non-deprived eye. Signup and view all the answers

How does amputating a finger affect the cortical region associated with it?

Initially stops responding, later responds to adjacent fingers. Signup and view all the answers

What is an example of cross-modal plasticity in sensory loss?

Blind humans experience better auditory localization. Signup and view all the answers

Which area of the brain is associated with spatial navigation in experienced London cab drivers?

Parahippocampus/posterior hippocampus Signup and view all the answers

Which statement best describes the phenomenon of phantom limb sensations?

Stimulation of adjacent body areas can trigger sensations in phantom limbs. Signup and view all the answers

What does consciousness encompass in terms of mental processes?

Both awareness and implicit processes. Signup and view all the answers

What is the primary area activated in blind individuals using echolocation?

Occipital cortex, including the primary visual cortex Signup and view all the answers

What occurs to the somatosensory map when two digits are sewn together?

The boundary between the two digits becomes less distinct. Signup and view all the answers

Study Notes

Holistic Processing

We recognize faces as a whole, not by individual parts (e.g., eyes, nose).
This processing works well for upright faces, but struggles with upside-down faces.
We can't process inverted faces holistically.
Research: Participants were good at identifying houses but struggled to identify a person ("Larry") when shown only their nose, but performed well with only their face.
The composite effect: Merging two faces creates a third person's face.
The face-inversion effect: We are better at recognizing upright faces.
Face cells in monkey IT: Specialized areas found in the inferior temporal lobe that respond mainly to faces. More research is needed to confirm their face selectivity.
Face cells in monkey STS: Demonstrated stronger responses to faces than other objects, suggesting a clear role in face recognition.

Prosopagnosia (Face Blindness)

Inability to recognize familiar faces, including family, celebrities, and even one's own reflection.
People with prosopagnosia may still recognize emotions in faces.
They can often recognize voices, even if they cannot recognize faces.
Recognition is difficult when obvious clues (hair, glasses, etc.) are missing.
Acquired prosopagnosia often arises from damage to the fusiform area of the brain (right hemisphere).
It's not a simple image-matching issue; it involves a step-by-step identification process.
People with acquired prosopagnosia may have difficulty identifying faces from different angles.
Prosopagnosia is not due to difficulty discriminating between different categories of faces.

Face vs. Object Recognition: One System or Two?

Prosopagnosia without object agnosia supports both possibilities.
Patient "CK" had agnosia without prosopagnosia, a rare condition that suggests two separate systems.
Patient CK couldn't see objects but could see faces.

Attention

What we perceive is not a direct copy of the world, but a product of our brain.

Attention to Visual Objects or Features

Attention types:
- Reflexive (Exogenous): Automatic, drawn to noticeable things.
- Voluntary (Endogenous): Chosen focus, directed by goals.
- Overt: Eyes focus on what you are paying attention to.
- Covert: Attention without eye or head movements.
Characteristics of attention:
- Limited capacity
- Selective
- Benefits speed and accuracy of processing

Covert Visual Attention

Focusing on a location without moving the eyes.
Helmholtz's Spotlight Theory: Attention acts like a spotlight illuminating specific locations for focus.
Posner Spatial Cueing Paradigm:
- Valid: Correctly cued location
- Invalid: Incorrectly cued location
- Neutral: No specific cue, both ways
Results:
- Attention speeds up processing.
- Exogenous vs. Endogenous orienting: Automatic vs. voluntary attention.
- Covert vs. Overt orienting: With vs. without eye movements.

Control of Attention Signals

Spatial shifts of attention are linked to the "fronto-parietal network," encompassing areas 6 and 7.

Attentional Control Network

Attention and eye movements are closely connected through the fronto-parietal network.
A significant overlap exists between networks for both attention and eye movement.

Spatial Attention in the Brain: ERPs During Spatial Cueing Task

Effects of attention are observed 70-100ms after a stimulus.
The occipital cortex plays a crucial role in spatial attention.

Modulation Effects

Attention boosts activity in areas specialized for the attended attribute.
For example, attention to motion increases activity in the Motion Area (MT).

Spatial Attention: Baseline Shifts in Retinotopic Cortex

Spatial attention changes the background activity levels in the retinotopic cortex.

Different Metaphors of Attention

Attention as a spotlight: Focused on specific areas or objects.
Attention as glue:
- Task: Finding an "X" among other shapes.
- Results:
  - Feature search: Fast detection with one red "X" or multiple red "X"s (parallel processing).
  - Conjunction search: Slower when many items are present, requiring careful analysis (serial processing).
Metaphor meaning: Attention combines shape and color.

Spatial Attention and Feature Integration

Key regions involved: Superior parietal cortex (SPL/IPS) and superior frontal cortex.

Nonspatial Attention

Attentional blink:
- Condition 1: Is there an "X"?
- Condition 2: Is there an "X" and what is the red letter?
- Results: Target detection takes time (due to attentional dwell time).

Selection and Unattended Information

Inattentional blindness: Failing to notice important events (e.g., invisible gorilla demo).
Change blindness: Missing significant changes in visual scenes (e.g., color card trick demo).

Early vs. Late Selection

Limited capacity: We can't process everything; we must select relevant information.
Historical Context:
- Broadbent's filtering (1958): Filtering happens early in the processing stream.
- Dichotic Listening Experiments (Cherry, 1950s): Early findings suggested minimal processing of unattended sounds.
Unattended Stimuli:
- Evidence shows minimal processing of unattended stimuli. For example, in a task requiring a pleasantness rating of RED shapes, participants showed good recognition of attended RED shapes but only chance level recognition of unattended GREEN shapes.

Visuospatial Neglect

Contralateral Neglect: Patients fail to respond to information on the side opposite their brain damage (contralesional space).
Common lesion location: Right temporal/parietal lobe.

Sensory Experience Alters Brain Development

Example: Removing mouse whiskers alters brain cell development.
Monocular Deprivation: Blocking one eye in infants leads to neurons responding only to the non-deprived eye.

Plasticity in the Adult Brain

Somatosensory Map Reorganization:
- Example: Sewing two digits together blurs cortical representation boundaries.
- Amputation: After finger amputation, the cortical region initially stops responding, later responding to adjacent fingers.
Auditory Cortex: Training on sound discrimination expands cortical representation of trained frequencies.
Motor Skill Learning: Finger tapping increases activity in the primary motor cortex for trained sequences.
Phantom Limb: Amputees experience sensations in the "phantom limb"; stimulation of adjacent body areas can trigger phantom limb sensations.

Sensory Loss/Deprivation:
- Blind humans show improved hearing and sound localization.
- Deaf humans have better peripheral vision.
Cross-modal Reorganization: Sensory cortex responds to a different modality when a primary sensory input is disrupted (e.g., vision shifts to touch in the blind).
Echolocation in blind subjects: Activates the occipital cortex, including primary visual areas.

Specialized Brain Regions

Spatial Navigation: Experienced London cab drivers have larger parahippocampus/posterior hippocampus regions.

Plasticity in Blind People

Echolocation: Blind people can use sound to navigate and discriminate shapes.
Activation: Echolocation activates the occipital cortex, including the calcarine sulcus (primary visual cortex).
Sound Processing: Even when the primary visual cortex processes sound, the lateral occipital cortex adapts to enhance auditory processing.

Consciousness

Consciousness involves awareness and mental representation of information, but also includes implicit processes and subliminal perception (processing without awareness).
Subjective Experience: The personal feeling of being, like the sensation of pain. Others can understand but cannot experience it themself.

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Description

This quiz explores the concepts of holistic face processing, including how we recognize faces as a whole rather than by individual parts. It delves into phenomena such as the composite effect and the face-inversion effect, as well as conditions like prosopagnosia, which is the inability to recognize familiar faces. Discover the fascinating research behind face recognition in both humans and monkeys.