Studied by 1 person
Computers + Object Perception
-Poor object perception -stimulus on receptor is ambiguous -objects can be hidden or blurred
Viewpoint invariance
-Object properties don't change when viewed from different angles -How humans recognize objects from different angles
Perceptual Organization
Small objects become perceptually grouped into larger objects
Gestalt psychology
-Principles of perceptual organization and figure-ground segregation -"Whole is different than the sum of its parts"
Structuralism
-Wundt -Perception results from the summation of sensations
Apparent movement
-Illusion of movement when two objects separated in space are presented rapidly, one after another, separated by a brief time interval -Perceptual organization creates movement (contradicts structuralism)
Illusory contours
Contour that is perceived even though it is not present in the physical stimulus
Principle of good continuation
Points, when connected, result in straight or smoothly curving lines seen as belonging together, following the smoothest path
Principle of Pragnanz/Good Figure/Simplicity
Every stimulus pattern is seen in a way that the resulting structure is as simple as possible
Principle of Similarity
Similar things appear to be grouped together
Principle of Proximity/Nearness
Things that are near each other appear to be grouped together
Principle of Common Fate
Things that are moving in the same direction appear to be grouped together
Principle of Common Religion
Elements that are within the same region of space appear to be grouped together
Principle of Uniform Connectedness
Connected regions of a visual stimulus are perceived as a single unit
Figure-ground segregation
The perceptual separation of an object from its background
Reversible figure-ground
-A figure-ground pattern that perceptually reverses as it is viewed (figure and ground switch) -Ex Rubin's vase-face pattern
Border ownership
When two areas share a border (in figure-ground displays) the border is usually perceived as belonging to the figure
Gibson and Peterson experiment
-Standing woman in a doorframe -Meaningfulness of stimulus matters
Scene
-A view of real-world environments -contains background elements -contains objects organized in meaningful ways relative to each other and the background
Gist of a scene
General description of a scene, can be perceived in 1/4 seconds
Persistence of vision
-Perception of any stimulus persists for about 250ms after the stimulus is physically terminated -Can be disrupted by visual masking
Visual masking stimulus
Visual pattern presented after a visual stimulus to decrease a person's ability to perceive the stimulus. Stops persistence of vision and effective duration of the stimulus
Global image features
Degree of naturalness, openness, roughness, expansion, and colour
Degree of naturalness
-Natural scenes have textured zones and undulating contours -Man-made scenes have horizontal and vertical straight lines
Degree of openness
Open scenes typically have a visible horizon line and contain few objects (Ocean and streets)
Degree of roughness
Smooth scenes (ocean) contain fewer small elements, whereas high roughness contain many small elements and are more complex
Degree of expansion
Convergence of parallel lines (ex. railroad tracks that appear to vanish in distance) have high degree of expansion. Dependent on observers, viewpoint
Physical regularities
-Regularly occurring physical properties of the environment -vertical + horizontal orientations more common than diagonals
schema
Observer's knowledge about what is contained in typical scenes
Likelihood Principle
Helmholtz; we perceive the object that is most likely to have caused the pattern of stimuli we have received
Unconscious Inference
Helmholtz; some perceptions are the result of unconscious assumptions that we make about the environment
Bayesian inference
-Perception determined by accounting for probability -Probability based on past experiences in perceiving properties of objects and scenes
Prior probability
In Bayesian inference, a person's initial estimate of the probability of an outcome
Likelihood
In Bayesian inference, the extent to which the available evidence is consistent with a particular outcome
Binocular Rivalry
-One image presented to OS, one image presented to OD, and perception alternates back and forth between the two images -Attention activates one brain area over another
Brain areas and facial responses
Occipital cortex: initial processing of face information FFA: Face identification Amygdala: Emotional aspects of faces + reactions to facial expressions STS: Evaluate where a person is looking + mouth movements Frontal cortex: Evaluate a face's attractiveness
Visual scanning
Moving the eyes to focus attention on different locations, on objects, or in scenes
Fixation
The brief pause of the eye that occurs between eye movements as a person scans a scene
Saccadic eye movement
Rapid eye movement between fixations that occurs when scanning a scene
Overt vs Covert attention
Overt: involves looking directly at attended object Covert: attention without looking
Visual salience
Characteristics that cause stimuli to stand out and therefore attract attention
Spatial attention
Attention to a specific location
Precueing
A cue stimulus is presented to direct an observer's attention to a specific location where a test stimulus is likely to be presented. Posner used this to show attention enhances processing of a stimulus presented at cued location
Binding
Features (colour, form,motion, location) are combined to create our perception of a coherent object. Occurs across senses
Binding problem
Problem of how neural activity in many separated areas in the brain is combined to create a perception of a coherent object
Feature integration theory (FIT)
Anne Treisman; explains how an object is broken down into feature and how these features are recombined to result in a perception of the object
Preattentive stage (FIT)
Automatic and rapid stage of processing, during which a stimulus is decomposed into individual features
Focused attention stage (FIT)
Stage of processing in which features are combined (requires focused attention)
Balint's Syndrome
Damage to parietal lobe, causing inability to focus attention on individual objects
Inattentional blindness
A stimulus that is not attended is not perceived, even though the person is looking directly at it
Change blindness
Difficulty detecting differences between two visual stimuli presented one after another. Also occurs when part of a stimulus is changed very slowly (Continuity errors)
Load theory of attention
Lavie; the amount of perceptual capacity that remains as a person is carrying out a task determines how well the person can avoid being distracted by task-irrelevant stimuli
Perceptual capacity
The resources a person has for carrying out perceptual tasks
Perceptual load
The amount of a person's perceptual capacity needed to carry out a particular perceptual task
Low-load vs high-load tasks
Low-load: uses small amount of person's perceptual capacity High-load: involve more processing and therefore use more of a person's perceptual capacity
Perceptual completion
Perception of an object as extending behind occluding objects
Habituation vs dishabituation
Habituation: Paying less attention when same stimulus is presented repeatedly Dishabituation: increase in responding that occurs when a stimulus is changed
Task-irrelevant stimuli
A stimulus that does not provide information relevant to the task at hand
Ecological validity
Gibson; An ecologically valid experiment matches its stimuli, conditions, and procedures to those present in the natural world
Optic flow
Flow of stimuli in the environment that occurs when an observer moves relative to the environment (gradient of flow and FOE are important characteristics)
Gradient of flow
Gradient created in optic flow by movement of an observer through the environment
Focus of Expansion (FOE)
The point in the optic flow pattern caused by observer movement in which there is no expansion (Where you are looking towards)
Invariant information
Environmental properties that do not change as the observer moves relative to an object or scene
Self-produced information
Environmental information that is produced by actions of the observer. (Ex: somersaults by experts vs beginner)
Swinging room experiment
Lee and Aronson; posture is corrected by vision
Visual direction strategy
A strategy used by moving observers to reach a destination by keeping their body oriented toward the target
Car Driving Experiment
Land and Lee; drivers don't look at FOE, instead look at the road where they are headed, and look at curves when turning
Wayfinding
Navigating through the environment by perceiving and remembering objects in the environment and their relation to the overall scene, knowing when to turn and in what direction (using landmarks)
Landmarks
Objects on a route that serve as cues to indication where to turn (used in way finding)
Topographical Agnosia
Patients unable to recognize landmarks in real-world environment due to parahippocampal gyrus damage
Cognitive Map
Mental map of the spatial layout of an area of the environment (Tolman; rat experiment in maze with cheese)
Affordances
Information specified by a stimulus pattern that indicates how the stimulus can be used
Parietal Reach Region (PRR)
In parietal cortex, involved in reaching behaviour
Monkey grasp experiment
Fattori; visuomotor grip cells: responds when an object is scene and also when hand grasps same object
Mirror neurons
Neuron in premotor area that respond when monkey grasps an object and when monkey observes someone else grasping the object
Audiovisual mirror neurons
Respond to actions that produce sound
Action-specific perception hypothesis
People perceive their environment in terms of their ability to act on it (perception changes based on skills and difficulty level)
Event
A segment of time at a particular location that is perceived by observers to have a beginning and an end
Event boundary
The point in time when one event ends and another begins
Akinetopsia
Damage to an area of the cortex involved in motion perception causes blindness to motion
Real motion
The physical movement of a stimulus
Illusory motion
Perception of motion when there actually is none
Induced motion
The illusory movement of one object that is caused by the movement of another object that is nearby
Motion aftereffects
Illusion that occurs after a person views a moving stimulus and then sees movement in the opposite direction when viewing a stationary stimulus immediately afterward (ex. waterfall illusion)
Optic array
The structured pattern of light created by the presence of objects, surfaces, and textures in the environment
Local disturbance in the optic array
Occurs when one object moves relative to the environment, so that the stationary background is covered/uncovered by the moving object. Indicates object is moving relative to the environment
Global optic flow
Information for movement that occurs when all elements in a scene move. Indicates the observer is moving and not the scene
Reichardt detector
Neural circuit in which signals caused by movement of a stimulus across the receptors are processed by a delay unit and an output unit so that signals are generated by movement in one direction but not the opposite direction
Output unit
Component of Reichardt detector; compares signals received from 2+ neurons. Activity in this unit is necessary for motion perception
Delay unit
Component of Reichardt detector; explains how neural firing occurs to different directions of movement. Delays transmission of nerve impulses as they travel from receptors towards brain
Corollary discharge theory
Explains motion perception as being determined both by movement of the image on the retina and by signals that indicate movement of the eyes
Image displacement signal (IDS)
In corollary discharge theory, the signal that occurs when an image moves across the visual receptors
Motor signal (MS)
In corollary discharge theory, the signal that is sent to he eye muscles when the observer moves or tries to move their eyes
Corollary discharge signal (CDS)
A copy of the motor signal that is sent to the eye muscles to cause movement of the eye. Copy is sent to the hypothetical comparator of corollary discharge theory
Comparator
Structure hypothesized by the corollary discharge theory. the CDS and IDS meet at the comparator to determine whether movement will be perceived
Real-motion neuron
Neuron in monkey's cortex that responds when movement of an image across the retina is caused by movement of a stimulus, but does not respond when movement across the retina is caused by movement of the eyes
Coherence
In movement perception research when arrays of moving dots are used as stimuli, the degree of correlation between the direction of the moving dots
Transcranial magnetic stimulation (TMS)
Presenting a strong magnetic field to the head that temporarily disrupts the functioning of a specific area of the brain
Aperture problem
A portion of the moving stimulus is seen through a narrow aperture or "field of view" of a neurons' receptive field, causing misleading information about the direction the stimulus is moving
Shorts path constraint
In apparent motion perception, the principle that apparent movement tends to occur along the shortest path between two stimuli (ex: women with hand infront vs behind head)
Note
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