Perception and Cognition: Spatial Vision
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Questions and Answers

What is the name of the model proposed by Marr regarding visual processing stages?

Marr’s model of vision

Which sense is associated with the receptor structure known as photoreceptors?

  • Taste/Smell
  • Hearing
  • Vision (correct)
  • Touch

    • Bottom-up processing is driven by knowledge and experience.

    False

    The primary visual cortex (V1) consists of two distinct classes of cells: simple cells and complex cells. Complex cells exhibit spatial ______ invariance.

    <p>phase</p> Signup and view all the answers

    Match the following visual illusions with their respective Gestalt law:

    <p>Proximity illusion = Proximity Similarity illusion = Similarity Continuity illusion = Continuity Closure illusion = Closure Common fate illusion = Common fate</p> Signup and view all the answers

    Which type of energy does the vision sense detect?

    <p>Electromagnetic energy</p> Signup and view all the answers

    What is the sensory function of Free nerve endings in the sense of touch?

    <p>Pain, temperature, tickle</p> Signup and view all the answers

    The Vestibular system is important for balance and posture control.

    <p>True</p> Signup and view all the answers

    The ______________ pathway is specific to sensations from the face, including touch, pressure, and pain.

    <p>Trigeminal</p> Signup and view all the answers

    What is the term used to describe the judgment of the location of objects in depth?

    <p>Depth perception</p> Signup and view all the answers

    Which cues are examples of monocular cues for depth perception? (Select all that apply)

    <p>Texture gradient</p> Signup and view all the answers

    Depth perception relies only on monocular cues.

    <p>False</p> Signup and view all the answers

    Binocular disparity arises from the slight difference in the views seen by each eye due to their approximately __________ cm separation.

    <p>6.3</p> Signup and view all the answers

    Match the following cues with their types: Texture gradient, Size, Occlusion, Disparity, Convergence

    <p>Monocular cue = Texture gradient, Size, Occlusion Binocular cue = Disparity, Convergence</p> Signup and view all the answers

    What is the definition of motion in the physical world?

    <p>Continuous change in an object's location as a function of time</p> Signup and view all the answers

    Saccades are slow movements of the eyes.

    <p>False</p> Signup and view all the answers

    What is the role of the Lateral Geniculate Nucleus (LGN) in vision?

    <p>Relay system between the retina and the primary visual cortex</p> Signup and view all the answers

    ____ have better temporal resolution than rods.

    <p>Cones</p> Signup and view all the answers

    Match each stream with its corresponding pathway:

    <p>Ventral Stream = &quot;What&quot; pathway Dorsal Stream = &quot;Where&quot; pathway</p> Signup and view all the answers

    What are some evolutionary advantages of motion detection?

    <p>Necessary for hunters</p> Signup and view all the answers

    What is Sensation?

    <p>Sensation = the information sent to the brain by our senses</p> Signup and view all the answers

    What is Perception?

    <p>Perception = our awareness of our environment</p> Signup and view all the answers

    What is the function of the Primary Visual Cortex?

    <p>Visual processing</p> Signup and view all the answers

    Sensory input from the physical world is directly identical to our brain's interpretation of it.

    <p>False</p> Signup and view all the answers

    Measuring perception is known as ________, pioneered by Gustav Fechner in the 1800s.

    <p>Psychophysics</p> Signup and view all the answers

    What is the role of mathematical models in sensory measurement?

    <p>To provide representations for sensory measurement</p> Signup and view all the answers

    What is the term used to describe the transmission of information to different areas in hierarchical sensory processing?

    <p>Hierarchical processing</p> Signup and view all the answers

    _______ experiments involve lesioning a section of an animal's brain to compare behavior.

    <p>Lesion</p> Signup and view all the answers

    Lesion experiments involve removing a specific region of an animal's brain.

    <p>False</p> Signup and view all the answers

    Match the following sensory experiences with their respective brain areas: Vision, Hearing, Touch, Taste/Smell

    <p>Primary Visual Cortex = Vision Auditory Cortex = Hearing Somatosensory Cortex = Touch Taste and Olfactory Cortex = Taste/Smell</p> Signup and view all the answers

    Study Notes

    Spatial Vision

    • Spatial vision is the ability to perceive the physical space around us
    • It involves the classification of senses, including:
      • Vision: detects electromagnetic energy through photoreceptors in the eyes
      • Hearing: detects air pressure waves through mechanoreceptors in the ears
      • Touch: detects tissue distortion through mechanoreceptors in the skin and muscles
      • Taste/Smell: detects chemical sensations through chemoreceptors in the nose and mouth
      • Balance: detects fluid movement through mechanoreceptors in the vestibular organs

    Marr's Model of Vision

    • Marr's model proposes that visual processing passes through a series of stages:
      • Primal sketch: the initial representation of the visual input
      • 2.5D sketch: a 2D representation with an illusion of depth
      • 3D sketch: a 3D representation of the visual input
    • Marr's model is influential, but not strictly correct, and is still a useful conceptual structure

    Primary Visual Cortex (V1)

    • There are two distinct classes of cells in the primary visual cortex (V1):
      • Simple cells: respond to oriented grating stimuli with a preferred orientation
      • Complex cells: respond to oriented grating stimuli with a preferred orientation, but with a wide range of spatial phases
    • Simple cells have periodic responses, while complex cells have steady responses in time

    Contrast Sensitivity

    • Humans are not equally sensitive to all contrasts
    • Contrast sensitivity is affected by spatial frequency
    • The human contrast sensitivity function shows that we are most sensitive to medium-range spatial frequencies

    Judging Distance

    • Judging distance involves:
      • Convergence (to be discussed in lecture 5)
      • Size
      • Texture gradients
    • Shape representation involves making inferences based on past experience, categorization, and Gestalt laws

    Gestalt Laws

    • Proximity: objects that are close together are grouped together
    • Similarity: objects that are similar are grouped together
    • Continuity: objects that are continuous are grouped together
    • Common fate: objects that move together are grouped together
    • Closure: objects that are incomplete are completed by the brain

    Shape Representation

    • Shape representation involves:
      • Bottom-up processing: driven by senses, allowing us to see shapes and infer meaning
      • Top-down processing: driven by knowledge and experience, allowing us to interpret what we see
    • Examples of top-down processing include the Stroop effect

    Special Visual Processing

    • Category-specific visual areas include:
      • Face-specific areas
      • Object-specific areas
      • Place-specific areas
    • Deficits in face processing include:
      • Prosopagnosia (face blindness)
      • Capgras syndrome (inability to recognize the identity of a person)

    Demystifying Visual Illusions

    • Using what we learned, we can understand how visual illusions work
    • Gestalt laws play a role in visual illusions, such as the proximity and similarity laws

    Introduction to Body Senses

    • The body senses include proprioception, somatosensory, and vestibular systems
    • These senses are responsible for knowing our location in space and maintaining balance and posture control

    Classification of the Senses

    • There are five traditional senses: vision, hearing, touch, taste, and smell
    • Each sense has a specific receptor, sensory structure, and cortex

    Somatosensory System

    • The somatosensory system is responsible for touch and proprioception
    • It includes various receptors that respond to different stimuli (e.g. pain, temperature, pressure)

    Touch Receptors

    • Free nerve endings: respond to pain, temperature, and tickle
    • Meissner's corpuscles: respond to light, dynamic touch
    • Merkel's disks: respond to static pressure
    • Pacinian corpuscles: respond to pressure and vibration
    • Ruffini's corpuscles: respond to stretching of skin

    Proprioception

    • Muscle spindles: respond to muscle length
    • Golgi tendon organs: respond to muscle tension
    • Joint receptors: respond to joint position

    Nervous System Pathways

    • There are three pathways: dorsal column-medial lemniscus, spinothalamic, and trigeminal
    • Each pathway is responsible for transmitting specific types of sensory information

    Somatosensory Perception

    • Two-point perception: the ability to distinguish between two points on the body
    • Object perception: the ability to recognize objects through touch

    Vestibular System

    • The vestibular system is responsible for maintaining balance and posture control
    • It codes information about body position in space
    • It includes the semicircular canals, otoliths, and vestibular labyrinth

    Vestibular System Anatomy

    • Semicircular canals: contain hair cells that respond to angular and linear acceleration
    • Otoliths: contain hair cells that respond to gravity and slow linear acceleration

    Body Senses in Action

    • Motion sickness: occurs when the body senses conflicting information about movement
    • Social and emotional touch: involves a special system for emotional touch, including social bonding and hormone release
    • Touch is necessary for development: humans need touch to develop psychologically

    Deficiencies

    • Touch blindness: the inability to feel touch
    • Age: touch and pain receptors reduce in accuracy as we age, vestibular system also declines with age

    Foundations of Perception and Cognition

    • Introduction to sensation and perception, methods, spatial vision, body senses, depth perception, and motion perception are the topics to be covered.

    Depth Perception

    • Depth perception is the judgment of the location of objects in depth.
    • The world is 3D, but we gather 2D information through the eyes, and our brain interprets this information to perceive the world as 3D.

    Monocular Cues

    • Texture gradient, size, and occlusion are monocular cues that help in depth perception.

    Binocular Cues

    • Binocular disparity, vergence, and stereo are binocular cues that help in depth perception.
    • Binocular disparity is the difference in views from each eye, providing a cue to depth.
    • On average, the pupils are 6.3 cm apart, which provides a slightly different view of the world from each eye.

    Binocular Disparity

    • Far (uncrossed) disparity occurs when a non-fixated point is further away, and the right eye's view of the point is shifted right relative to the left eye's view.
    • Near (crossed) disparity occurs when a non-fixated point is nearer away, and the right eye's view of the point is shifted left relative to the left eye's view.

    Testing Depth Perception

    • The RanDot Stereo test is used to test depth perception.

    Random Dot Stereogram

    • A random dot stereogram is a test developed by Bela Julesz to demonstrate how stereo vision is perceived in the brain.
    • It demonstrates that stereoscopic depth is perceived in the absence of contextual cues.
    • About 5% of people cannot see the depth in random-dot stereograms.

    Autostereogram (Magic Eye 3D Art)

    • An autostereogram is a 3D image that can be viewed without glasses or other devices.
    • It creates a sense of depth perception in the brain.

    Binocular Rivalry

    • Binocular rivalry is the phenomenon where the brain switches between the images from each eye.

    Note: These notes focus on key facts and concepts related to depth perception, binocular cues, and testing depth perception, with a concise and engaging format.

    Introduction to Motion Detection

    • Acknowledgement of Kaurna people, traditional custodians of the land
    • Warning about photosensitive epilepsy due to geometric shapes and patterns in the lecture

    What is Motion?

    • Definition: continuous change in an object's location over time
    • Physical world (reality): object's physical movement against its background
    • Retina (sensory): change in physiological reaction of photoreceptors at the same rate as the object's transition
    • Brain (perceptual): ability to discern distance and speed of a moving object in response to sensory input
    • Types of motion: real motion, apparent motion (includes motion illusions like beta, phi, and induced motion)

    Motion Detection

    • Real motion: physical movement of a stimulus against its background
    • A note about saccades: quick eye movements that help track objects, with the brain filling in gaps to create a smooth impression

    Physiology of Motion Detection

    • The retina:
      • Cones have better temporal resolution than rods
      • Rods have a longer refractory period than cones
    • Lateral Geniculate Nucleus (LGN): relay system between retina and primary visual cortex
    • Directional cells (V1): respond to specific directions of motion
    • Extra-Striate Cortex: encompasses areas V3, V4, V5/MT, sensitive to motion
    • Motion pathways:
      • Retinotectal pathway: reactive, primitive
      • Geniculo-cortical pathway: complex, cortical (thinking)
      • Ventral stream: "what" pathway, object recognition and form representation
      • Dorsal stream: "where" pathway, guidance of actions and recognizing objects in space

    Functionality of Motion Detection

    • Evolutionary advantages: essential for both predators and prey
    • Functionality of motion detection: figure and ground segregation, ambient motion, and motion parallax
    • Deficiencies in motion detection: patient LM, who lost ability to detect movement after traumatic brain injury (TBI)

    Exam Advice and Summary

    • Use lecture slides to guide studies
    • Summative quiz available to assess knowledge
    • Material from SDL, tutorials, and lectures are assessable
    • Readings and chapter references support lecture material
    • Summary: motion, physiology of motion detection, and functionality of motion detection

    Introduction to Sensation and Perception

    • Sensation is not the same as perception
    • Sensation is the information sent to the brain by our senses, whereas perception is our awareness of our environment
    • Perception is the foundation for everything else in psychology, including memory, learning, motor skills, emotion, motivation, social psychology, personality, and pathology

    Classification of the Senses

    • Vision: electromagnetic energy, photoreceptors, eyes, primary visual cortex
    • Hearing: air pressure waves, mechanoreceptors, ears, auditory cortex
    • Touch: tissue distortion, mechanoreceptors, thermoreceptors, skin, muscle, somatosensory cortex
    • Taste/Smell: chemical, chemoreceptors, nose/mouth, taste and olfactory cortex
    • Balance: mechanoreceptors, vestibular organs, temporal cortex

    A Closer Look at Vision

    • The retina is responsible for processing visual information
    • Distribution of rods and cones in the retina affects visual resolution
    • The visual pathway: light enters the eye, passes through the cornea, pupil, lens, and retina, and is processed in the brain
    • What we see: the world appears high-resolution across the visual field, but in reality, visual resolution varies across the visual field

    Measuring Perception

    • Psychophysics is the study of the relationship between physical stimuli and their perception
    • Measurement properties: threshold, absolute threshold, classical idea, and psychometric function
    • Methods: method of adjustment, method of limits, and method of constant stimuli
    • Example: measuring the minimum amount of light needed to detect a stimulus

    Using Measurements

    • Colour vision: starts with cones in the retina, three types of absorption spectra for cones
    • Human colour sensitivity: most sensitive to 560nm, daylight levels
    • Colour perception varies across species: humans, cats, possums, and dogs
    • Colour vision deficiency: more common in men, two most common types are deuteranopes and protanopes
    • Ishihara colour plates: used to test for red/green colour blindness

    Introduction to Sensation and Perception

    • Perception lectures cover various topics, including intro to sensation and perception, methods, spatial vision, body senses, depth perception, and motion perception
    • Warning: animal experimentation will be discussed in the lecture

    Mathematical Models for Sensory Measurement

    • Debate about representations for sensory measurement
    • Classification of the senses:
      • Vision: electromagnetic energy, photoreceptors, eyes, primary visual cortex
      • Hearing: air pressure waves, mechanoreceptors, ears, auditory cortex
      • Touch: tissue distortion, mechanoreceptors, skin, muscle, somatosensory cortex
      • Taste/Smell: chemical, chemoreceptors, nose/mouth, taste and olfactory cortex
      • Balance: mechanoreceptors, vestibular organs, temporal cortex

    Hierarchical Stages of Sensory Processing

    • Hierarchical processing of sensory information involves transmission of information to different areas
    • Lower levels control, modify, and modulate the process
    • Result: stark perceptual errors
    • Stevens' power law: relationship between the strength of a physical stimulus and the perceived magnitude increase

    Using Deficiencies to Measure Sensation

    • Lesion experiments:
      • A section of an animal's brain is lesioned (through surgery or ablation)
      • Behavior in the lesioned animal is compared to an intact animal
    • Example: Ferrier (1876) removed the angular gyrus of monkeys, concluding that the animals were now blind (but vision is processed largely in occipital cortex, not in the gyrus)
    • Pros and cons of lesion experiments:
      • Can remove specific regions
      • Helps establish the idea of localisation of function
      • However, discrete areas of brain function are rare

    Clinical Studies

    • Patients with brain injury (e.g., trauma, disease)
    • Assess functional and anatomical extent of insult
    • Insight into brain function by comparing patient behavior to non-injured person
    • Example: Patient DF with visual apperceptive agnosia due to bilateral lesion to her lateral occipital cortex
    • Patient DF:
      • Unable to judge the width of an object by using her thumb and forefinger
      • However, when asked to pick it up, her hand moves to the correct width
      • Thus, she cannot judge features of the object but is able to control her actions with that information

    Using Perception to Measure Sensation

    • Psychophysics:
      • Investigating the relationship between stimuli and the sensations and perceptions they produce
      • Methods: method of limits, method of constant stimuli, method of adjustment
    • Pluses and minuses:
      • Non-invasive technique
      • Relatively inexpensive
      • Relies on participant judgment
      • Behavior is often what matters - useful information for applied areas (e.g., human factors, assessment of disease)

    Using Neural Function to Measure Sensation

    • Single Unit recordings:
      • Record the change in action potential of a single cell (neuron)
      • Record from awake, behaving or anesthetized animals
    • Pros and cons:
      • Excellent spatial and temporal resolution
      • Only a very small window into brain activity
      • Long, expensive experiments
    • Functional Magnetic Resonance Imaging (fMRI):
      • Measures change in blood flow
      • Shows brain activity
      • Has been used to infer localisation of function
    • Comparing temporal, spatial, and resolution of different techniques:
      • fMRI
      • Single unit recordings
      • Lesion experiments

    Summary

    • Reference: Barlow, H (1972): Single units and sensation: A neuron doctrine for perceptual psychology. Perception 1:371-394.
    • Reference: Mather, G (2016): Foundations of perception. Psychology Press Ltd., Hove. Chapter 1.

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    Related Documents

    Perception Lecture 1.3 PDF
    Perception Lecture 1.4 Senses PDF
    Perception Lecture 1.5 Depth PDF
    Perception Lecture 1.6 Motion (PDF)
    PSYCH_2006 Lecture Foundations of Perception and Cognition PDF
    Foundations of Perception and Cognition Lecture Notes PDF

    Description

    Learn about the foundations of perception and cognition, covering topics such as intro to sensation and perception, methods, and spatial vision. Acknowledging the traditional custodians of the Kaurna people's ancestral lands.

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