Perception Flashcards
(280 cards)
1
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Perception
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The acquisition of knowledge by an organism about its environment
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Sensory Phenomena
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General feelings, urges, or bodily sensations (raw sensory input)
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Vision
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Electromagnetic radiation
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Hearing
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Mechanical vibrations
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Touch
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Mechanical perturbations of the skin
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Smell
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Chemical properties of gases
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Taste
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Chemical properties of solids and liquids in contact with the tongue
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Temperature
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Heat
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Sensory Perception
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The acquisition of this knowledge via the senses
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Perceptual Phenomena
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The way individuals organize, identify, and interpret sensory information, ultimately leading to the understanding of the presented information or environment (conscious experience and interpretation)
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Top-Down
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How the brain interprets sensory information by applying prior knowledge, expectations, and context
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Bottom-Up
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A perception process that begins with raw sensory data and moves upwards to higher-level cognitive processing, relying on the stimulus itself to create meaning
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Psychophysics
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The scientific study of matter and energy related to the mind and brain; try to relate a precisely defined physical stimulus, with a precisely measured behavioral response
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Method of Limits
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The stimuli start low enough to be undetectable and gradually increase over time until they can be detected
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Method of Adjustment
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The subject is asked to control the level of the stimulus and to alter it until it is just barely detectable against the background noise, or is the same as the level of another stimulus
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Staircase Methods
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A variable stimulus is presented repeatedly and is adjusted upwards whenever it is not perceived and downwards whenever it is perceived
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Method of Constant Stimuli
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Presenting variable stimuli in random order and determining the smallest intensity that can be detected in the case of an absolute threshold or the smallest difference from a standard stimulus that can be detected in the case of a difference threshold
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Absolute Threshold
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The smallest amount of stimulus energy necessary for an observer to detect a stimulus
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Difference Threshold
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The smallest amount something must change in order for a person to notice the change 50% of the time
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Psychometric Function
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A graph that illustrates the relationship between a stimulus’s intensity or parameter and an observer’s response or decision-making
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JND
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The smallest amount something must change in order for a person to notice the change 50% of the time
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Weber’s Law
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The ratio of the JND (Δl) to the intensity of the stimulus (l)
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Weber Fraction
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Δ l/l = k
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Magnitude Estimation
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A method where participants assign numerical values to stimuli to reflect their subjective perception of intensity or magnitude (grey circle example)
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Theories of Perception
Levels of explanation like anatomical and physiological, behavioral and psychological, theoretical and philosophical; perceptual theories like physiological approach (indirect), ecological approach (direct), computational approach (indirect)
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Physiological Approach (Barlow)
Understanding neurones, how they react to perceptual stimuli and they interact with each other, is the key to understanding perception; chief techniques were single-unit electrophysiology coupled with psychophysics and now its neuroimaging
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Ecological Approach (Gibson)
Little to be gained from laboratory experiments, perception must be studied in the “real world”; chief techniques are observation of behavior in natural environments, analysis of how “the optic array” changes as observers move around the world, the use of virtual environments
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Computational Approach (Marr)
Perception is information processing, the successive transformation of sensory data from one form to another; chief techniques are computer-based analysis of information content of stimuli from which properties of perceptual systems can be inferred
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Phenomenological Approach
A qualitative research method that focuses on understanding human experiences from the perspective of the individual
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Optic Array
The patterns of light that reach the eye and contain all the visual information available at the retina (the visual scene as perceived); determined by sources of light and reflectors of light
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Visual System
Light -> eye -> retina -> optic chiasm -> LGN -> striate cortex -> extrastriate cortex; converts a structured pattern of light to a perception of a solid three-dimensional world
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Intensity
Characteristic of light; intensity increases as the number of photons per second increases
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Visual Encoding
The process of converting visual sensory information into a form that can be stored and retrieved in memory (there are encoding principles)
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Principle of Least Commitment
Don’t throw away any information that you might need later on
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Principle of Least Redundancy
Encode information as efficiently as possible
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Principle of Graceful Degradation
If the system breaks, it should still be usable
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Retina
The light-sensitive tissue at the back of the eye that receives images and transforms them into electrical signals
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Receptive Fields
The region of retina that, when stimulated, influences the firing rate of the neuron
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Phototransduction
Turning light into electricity; photons of light are absorbed by visual pigment molecules, the subsequent chemical changes result in an electrical signal
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Photoreceptor
Rods and cones; involved in phototransduction
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Rods and Cones
Photoreceptors; rods are highly sensitive to light and primarily responsible for vision in low light conditions; cones enable color vision and help with shard visual detail in bright conditions; operates at a large range of light levels; retains information about wavelength content of light by differential activation of L,M,S cones; position and intensity also encoded
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L, M, and S Cones
Color space which represents the response of the three types of cones of the human eye (long, medium, small)
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Spectral Sensitivity
The ability of a photoreceptor to convert light into a physiological signal that induces a biological, visual, or non-visual response
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Visual Electrophysiology
Experiments normally performed on animals; tiny electrode placed close (or sometimes inside) a visual neurone; visual stimuli are presented to the animal and the electrical signals in the neurone are recorded
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Metamer
A stimuli that, while physically different, is perceived as the same by the human eye under specific conditions, particularly related to color
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Bipolar Cell
Type of neuron found in the retina; receive input from photoreceptors and transmit signals to retinal ganglion cells
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Spike Train
A sequence of recorded times at which a neuron fires an action potential
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Lateral Geniculate Nucleus (LGN)
Bilateral nucleus, 6 layers (1,4,6 from contralateral eye in opposite hemisphere and 2,3,5 from ipsilateral eye in same hemisphere), retinotopic organization; similar (centre-surround) receptive fields to ganglion cells, little modification of the response, may regulate information flow from retina to cortex; position encoded retinotopically
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Retinal Ganglion Cell
Act as a bridge between where light is captured and the brain’s visual processing centers; respond with a series of nerve impulses (spike train) and more stimulation means increased firing rate; responds to contrast between center and surround
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Centre/Surround Structure
Central ON area in which stimulation tends to excite neural responses and a surrounding OFF area in which stimulation tends to suppress neural responses by lateral inhibition
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Retinotopy
The organized mapping of visual information from the retina onto neurons in the brain, particularly within the visual cortex
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M, P and K Cells
Used in LGN parallel processing; fast temporal changes (M pathway), fine detail and red-green color (P pathway), blue-yellow color (K pathway
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Simple Cells
Neurons in the V1 that respond selectively to specific orientations of lines or edges; have receptive field with distinct excitatory and inhibitory regions and their responses are linear and spatially localized (orientation selective)
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V1/Striate Cortex/Primary Visual Cortex
Striate means stripey, 6 layered structure (different from LGN); still hotly debated (as highly complex), probably no conscious access, probably not the “seat” of visual perception, more refined responses than LGN, essentially blind without it
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End-Stopped Cells
Respond most strongly to a line of a specific length or a corner of a stimulus, have weaker or no response when line/corner extends beyond a certain point; help perceive shapes/objects more accurately (length tuned, respond to moving angles and corners)
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Complex Cells
Respond to bright and dark bars/edges; insensitive to their position in the receptive field (direction and orientation selective)
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Hierarchal Structure
The receptive field units at one level of the hierarchy are constructed by combining inputs from units at a lower level
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Orientation Tuning
The degree to which a neuron or a population of neurons responds selectively to a specific orientation of a stimulus (line/edge); way of filtering out and emphasizing certain orientations
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V2
Color, form depth (encoding in extra-striate cortex)
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Extra-Striate Cortex
A brain region central to mental representations of motion, situated along the perception-cognition continuum in neuroscience; a large number of separate areas of the brain have a visual input; beyond V1 receptive fields get bigger and more specialized
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IT
Complex form (encoding in extra-striate cortex)
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V3
Motion, form (encoding in extra-striate cortex)
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V5/MT
Motion, depth (encoding in extra-striate cortex)
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V4
Color, shape (encoding in extra-striate cortex)
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MST
Motion in depth (encoding in extra-striate cortex)
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Inferotemporal Cortex (IT)
Critically involved in the recognition of visual objects, scenes, faces, and written words (temporal lobe)
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Dorsal/Action Pathway
Computes the location of visual objects and the actions related to those objects (parietal pathway)
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Ventral/Perception Pathways
Responsible for processing visual information about objects and their characteristics such as shape, color, and texture (temporal pathway)
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Spatial Frequency
The rate of change in luminance or contrast across space, typically measured in cycles per degree of visual angle; describes how rapidly an image changes
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Binocular Disparity
Difference in receptive field position between the eyes, helps in depth perception
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Scene Perception
A view of a real-world environment, contains background elements, contains multiple objects, these objects are organized in a meaningful way (relative to each other and the background); scenes are acted within
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Gestalt Rules
Rules that explain how the human mind organizes visual information, grouping elements into meaningful wholes rather than individual parts
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Object Perception
Making sense of visual information enabling us to recognize and categorize objects in our environment; objects are acted upon; combine elementary features into extended contours and shapes, Gestalt rules (grouping rules)
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Natural Scene
A visual stimulus that contains multiple elements arranged in a spatial layout, typically resembling scenes found in the natural world
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Illusory Contours
Visual illusions where perceived edges or borders are present, despite the absence of a physical edge or change in luminance or color
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Grouping
The human tendency to organize information and stimuli into coherent groups or categories
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Similarity
Elements perceived as similar are grouped together, despite their physical separation
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Good Continuation
Gestalt principle about how there is an innate tendency to perceive a line as continuing its established direction; lines, curves, and shapes continuous rather than disconnected elements
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Proximity
Things that are close together appear to be more related than things that are spaced farther apart
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Perceptual Segregation
The process of distinguishing individual objects or figures from their background or other objects
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Kanicza Triangle
Example of illusory contours; the three circles and v’s that create a triangle illusion
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Viewpoint Invariance
The ability to recognize an object, regardless of the viewing angle or orientation (viewpoint invariance, 3-D model vs multiple views)
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Object Categorization
The way we sort objects into groups, known as cognitive categories, that help us organize knowledge; super-ordinate (animal), basic (dog), subordinate (golden retriever)
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Scene Gist
General description of a scene; available after only a fraction of a second (degree of naturalness, openness, roughness, expansion, color)
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Perceptual Inference
The ability to infer sensory stimuli from predictions that result from internal neural representations built through prior experience
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Superstitious Perception
When no natural cause can explain a situation, attributing an event to a superstitious cause may give people some sense of control and ability to predict what will happen in their environment
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TE, TEO
Sub-regions of the inferotemporal cortex; seen as the endpoint of the “ventral” or “what” processing stream
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Cognitive Toponymy
The study of what place names can tell us about how people conceptualize their environment
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Fusiform Face Area (FFA)
Primarily involved in perception and recognition of faces (structure in the temporal cortex)
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Extra-Striate Body Area (EBA)
Highly sensitive to the perception of human bodies and body parts (structure in the temporal cortex)
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Occipital Face Area (OFA)
Specifically involved in early, low-level processing of facial features (structure in the temporal cortex)
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Parahippocampal Place Area (PPA)
Crucial role in processing and recognizing scenes and spaces, particularly spatial layout (structure in the temporal cortex)
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Visual Word Form Area (VWFA)
Primarily responsible for processing the visual shapes of words, rapid recognition of units rather than individual letters (structure in the temporal cortex)
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Lateral Occipital Complex (LOC)
Responds more strongly to a variety of object shapes, as compared with textures, noise patterns, scrambled objects...
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Diagnosticity
The extent to which a source of data can discriminate between a particular hypothesis and its alternatives
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Grandmother/Jennifer Aniston Neuron
A hypothetical neuron that responds only to a highly complex, specific, and meaningful image, such as the image of one’s grandmother
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Affordance
The potential actions that an object or environment offers to a perceiver
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Pre-Attentive Stage
The unconscious, rapid processing of basic features of a stimulus before focused attention is directed to it
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Divided Attention
Paying attention (or trying to pay attention) to more than one thing at a time; common in everyday life (driving)
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Exogenous Attention
Guided by the environment
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Selective Attention
Focusing on specific objects and ignoring others
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Inattentional Blindness
We often do not perceive an object or event if we do not attend to it (especially for dynamic events)
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Endogenous Attention
Guided by the attender (internally)
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Change Blindness
When scenes change between two discrete views we are not sensitive to large differences between scenes; can be alleviated if location of change is cued, motion is sensitive to these changes
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Spotlight of Attention
Focuses on how we consciously process specific stimuli, much like a flashlight in a dark room
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Continuity Error
Sometimes film-makers make mistakes called continuity error; can be due to inattentional blindness (glaring errors go unnoticed in a single scene) or change blindness (an error that occurs following a cut in the action)
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The Binding Problem
Early vision is modular, analyzing separate features separately (color, orientation, motion), but when we see an object, all of these attributes are attached to it (is it attention that binds them together)
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Modularity
Idea in early vision where features were analyzed separately
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Feature Integration Theory (FIT)
Object -> pre-attentive stage (features free-floating) -> focused attention stage (features bound together) -> perception
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Focused Attention Stage
The subject combines individual features of an object to perceive the whole object
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Parallel Search
A process where the brain simultaneously assesses multiple items or stimuli in a visual display, searching for a target
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Illusory Conjunction
The phenomenon where individuals mistakenly perceive or combine different features from two different objects as belonging to a single object
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“Pop-Out”
The phenomenon where a unique target stimulus is quickly and easily detected among a group of similar distractors
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Conjunction Search
A process where the target object is identified by combining two or more features
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Serial Search
A cognitive process where information or objects are examined one by one, sequentially, until a target is found or a decision is made about its absence
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Binding by Synchronization
The hypothesis that the brain integrates information from different area by synchronizing the firing patterns of neurons
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Gamma Band Oscillation
Control the connectivity between different brain regions (important for perception, memory, movement, and emotion)
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Photoreceptor Distribution
Rods outnumber cones by a ratio of 20:1 or greater in the retina, but in the fovea the cone density is the highest and correlated with visual acuity
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Central Vision
The ability to see objects directly in front of you, typically with clear detail and focus
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Apparent Motion
The perceptual illusion of movement where stationary objects appear to be moving, typically due to the brain’s interpretation of a sequence of stimuli
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Peripheral Vision
Encompasses the visual field to the sides and above/below without needing to move your head
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Eye Movement
Involved in directing our attention to different parts of a scene
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Stimulus Salience
The degree to which a stimulus stands out or grabs attention, making it more likely to be noticed and processed; we direct our eyes to the most “salient” object; works on a computer screen, but not always in the real world
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Autism
Typically the eye gaze is allocated to the right place and at the right time to guide actions, however, this can be different in some neurodivergent conditions
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Monotropism
A theory of autism which has emerged from the experiences of autistic people; the tendency for an autistic person’s interests to draw them in more strongly than a non-autistic person (“interest” model); in a “monotropic mind” fewer interests are aroused, and they attract more processing resources so it is harder to deal with things outside of these interests
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Attentional Enhancement
Attention can enhance perception, we respond faster to attended objects/locations and in some cases, contrast is also enhanced; attention enhances physiological responses, in the parietal cortex, firing rates of visual neurons increase if an object in the receptive field is attended
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Delay and Compare
Measure image at one place and time and then later at another place and time
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Motion Perception
Motion of objects in the 3D world causes changes in the retinal image; instead of a blurry smeared mess we typically perceive the movement of solid objects
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Motion (Reichardt) Detector
Human motion detector activity; our perception of motion depends on the outputs of these motion detectors
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Static Motion Illusion
Any optical illusion in which a static image appears to be moving due to the cognitive effects of interacting color contrasts, object shapes, and position (spiral disks)
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Correspondence Problem
The challenge of identifying corresponding elements or features between different images or frames when those images are taken from different perspectives or at different times
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Nearest Neighbor Matching
Preferred by the visual system to solve the correspondence problem (think of the squares in a box)
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Common Fate
A Gestalt principle of organization that describes how people tend to perceive visual elements that move together as a single unit, even if they are not physically connected
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Aperture Problem
The area seen by any one motion detector is small, this causes problems for determining the direction of motion of a moving object
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Barber Pole Illusion
The stripes on a barber pole look like they are going up, but they are really just going around; ambiguous motion at center of stripe and unambiguous motion at edge
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Optic Flow
The pattern of retinal motions that we see if we move towards or away from an object; gives useful information about speed and direction of “heading”
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Heading
Direction of movement
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Corollary Discharge
A neural signal, essentially a “copy” of a motor command, that is sent to sensory areas of the brain
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Area V/MT
Think that the fields in V5/MT are built up from component motion detectors with smaller receptive fields; direction of motion
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Areas MST, FST
MSTd (self motion), MSTv (trajectories), FST (actions)
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Self-Motion
The perception and experience of one’s own body moving through space (MSTd)
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hMT+, V3
Core region involved in motion perception (hMT+); relates to dynamic form and processing motion (V3)
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Action Perception
The idea that our perception of the environment is influenced by our ability to act within that environment, and conversely, our actions are guided by what we perceive (FST)
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Vestibular Form
Our experience of motion, balance, and body position
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Superior Temporal Sulcus (STS)
Involved in understanding others’ actions, recognizing emotions from body movements, and processing social information (like gaze direction)
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Biological Motion
The visual perception of a living being’s movement, including actions like changes in facial expression, eye gaze, and body movements Attaching lights to joints and film a human moving in a dark room (can see properties of action, identity, emotion, gender and scrambling the dots makes the motion more difficult to see)
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Point-Light Display
Attaching lights to joints and film a human moving in a dark room (can see properties of action, identity, emotion, gender and scrambling the dots makes the motion more difficult to see)
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Wavelength
We associate a particular wavelength of electromagnetic radiation with a particular color sensation
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Benham’s Disc
A rotating black-and-white disk produces the illusion of color
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Color Diagnosticity
The degree to which a specific color is associated with or symbolizes a particular object; this can make us confused/uncomfortable if the color isn’t right; also, can help us narrow down the search or identify specific exemplars
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Spectral Reflectance
The measurement of the amount of light reflected by a surface at different wavelengths across the electromagnetic spectrum; important for color constancy
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Memory Colors
The color an individual associates with a specific object based on their experience and knowledge of that object; prior knowledge of an object’s characteristic color affects its appearance
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Trichromacy
The ability of the human eye to perceive a wide range of colors due to the presence of three different types of cone cells in the retina (three cone types with three cone pigments)
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Young-Helmholtz Theory
Vision is based on how every combination of color perceived by the brain is a combination of blue, green, and red (picked up on by different cones)
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Spectral Sensitivity
The ability of a photoreceptor to convert light into a physiological signal that induces a biological visual or non-visual response
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Color Matching
How every color can be made by combining blue, green, and red (from different cones)
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Metamer
A psychophysical color match between two patches of light that have different sets of wavelengths; activate cones by same amounts; most color measurement is via metameric matching; this is how we can stimulate colors on computers, televisions, etc.
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Blob/Interblob
Blobs are groupings/clusters of similar-colored pixels they contain wavelength-sensitive cells; interblobs are the most responsive to high spatial frequencies
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Opponent-Process Theory
Proposes that some colors are perceived in opposite pairs; when one color is perceived, its opponent color is suppressed
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Forbidden Colors
Composed pairs of hues whose light frequencies automatically cancel each other out in the human eye, they’re supposed to be impossible to see simultaneously
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Ocular Dominance
The brain’s preference for visual information from one eye over the other, even when both eyes are open
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Color Contrast
The difference in visual perception between two colors, particularly in terms of their lightness or darkness, and how that difference impacts how we see and interpret elements within a visual composition
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Double Opponent Neuron
Respond only to color contrast; thought to be in V1; existence controversial; maybe basis for simultaneous color contrast
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Simultaneous Color Contrast
The phenomenon where the perceived color of a patch is affected by the colors surrounding it
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Unique Hue
Pure, unmixed colors that serve as fundamental building blocks of color perception; perceived when one of the two chromatic processes is polarized in one direction and the other opponent process is at equilibrium
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Spectral Power Distribution
Specifies the amount of power it contains at each wavelength in the visible spectrum, often taken to lie roughly between 400 and 700 nm
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Object Color
Determined by spectral distribution of reflected light (spectral power distribution of illuminant, spectral reflectance function of object); but we don’t want objects to look different when the illumination changes
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Color Constancy
Colors stay “constant” under changes of illuminant; colors do not appear to change moving from daylight to artificial light or at different times of day; this is achieved through chromatic adaptation, effects of context, memory effects
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Chromatic Adaptation
The process by which the visual system adjusts its sensitivity to color in response to changes in the spectral composition of light
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Lightness Constancy
We tend to calibrate using the lightest and darkest things we can see; what we see as white and black is relative; lightness constancy also helps us to distinguish shadows from material changes
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“The Dress”
Is it blue and black, or white and gold
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“Color as Material” Assumption
Color adds information for detection, identification, grouping, memory; object boundaries (color and lightness changes), shadows and shading (lightness but not color), are color changes more reliable indicators of object boundaries than lightness ones
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Proprioception
Sense of position of the limbs
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Tactile Perception (Somaesthesis)
Sense of objects touching the skin
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Kinesthesia
Sense of movement of the muscles
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Somatosensory System
Includes receptors, spinal pathways, and brain regions
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Merkel Receptors
Respond to continuous pressure (sustained response); involved in sensing fine details
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Meissner Corpuscles
Respond to application and removal of stimulus (transient response); involved in handgrip control
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Pacinian Corpuscles
Respond to stimulus onset and offset (transient response); detect vibration and also fine texture (by moving fingers)
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Ruffini Endings
Respond to continuous pressure (sustained response); detect stretching of skin; controversial (Yantis says “unknown here”)
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Sustained/Transient
Sustained is held over periods of time and transient is not
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Fast Adapting/Slow Adapting
Fast happens very quickly the response is strong, brief, and response rapidly decreases when stimulus is sustained; slow happens over longer periods and the response maintains as long as the stimulus is present
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C-Tactile (CT) Mechanoreceptors
Nerve receptors in mammalian skin that generally respond to non-painful stimulation such as light touch
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Free Nerve Endings
Unspecialized sensory nerve receptors that detect various stimuli, including pain, temperature, and pressure
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Glabrous/Non-Glabrous
Glabrous skin is smooth, having a surface without hairs or projections (palms of the hands), and non-glabrous is the opposite
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Myelinated/Non-Myelinated
Non-myelinated fibers are slow conducting
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Tactile Receptive Field
The specific area of the skin surface where a tactile stimulus will evoke a response in a sensory neuron
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Two-Point Discrimination Threshold
The smallest distance between two stimuli such as tactile stimuli on the skin, that a person can perceive as two distinct sensations rather than one
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Sensory Homunculus
The cortical area for different body parts is roughly equivalent to sensitivity
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Somatosensory Cortex
Area of the brain responsible for processing sensory information; maps in somatosensory cortex can change by increasing the amount of stimulation to a part of the map; receptor axons -> spinal pathways
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Plasticity
Expert string players have more cortex devoted to their left hand than their right, suggests the adult brain is flexible
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Medial Lemniscal Pathway
Spinal pathway responsible for fine touch
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Spinal Pathway
Includes the medical lemniscal pathway and the spinal-thalamic pathway
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Spinal-Thalamic Pathway
Spinal pathway responsible for pain, itch, crude touch
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S1, S2
The cortical areas in the somatosensory cortex; Somatosensory receiving area (S1) is responsible for processing sensory information related to touch, temperature, pain, body position; secondary somatosensory cortex (S2) integrates discriminative information from S1 with noxious input directly received from subcortical structures
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Itch, Pain
Follow the same neural pathways to the brain; itch stimuli evoke scratching while pain stimuli induce withdrawal reflex; itch originates from the skin and pain from all body parts; itch is inhibited by pain
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Ventro-Posterior Nucleus (VPN)
Part of the thalamus that receives ascending sensory information from the spinal cord’s lateral column and sends somatosensory information to the neocortex
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Thermoreception
The process by which an organism perceives and responds to changes in temperature, specifically the sensation of hot and cold
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Haptics
Investigates how we use our somatosensory system to evaluate the world around us; results are active touch is more sensitive than passive touch, and standard exploratory techniques used
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Active Touch
When we actively use our hands to explore objects in the world, we are more efficient at gaining information than when an object is moved passively across our hands
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Phases of Pain
Two phases of pain, like stubbing a toe vs touching a hot plate
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Exploratory Procedures
The way we explore objects with our hands is tailored to the amount of information that we hope to gain (lateral motion, pressure, enclosure, contour following)
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A-Delta/C-Fibres
A-delta are myelinated, fast conducting, and deal with initial, sharp pain; C-fibre are unmyelinated, slow conducting, and deal with more prolonged and less intense pain
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Affective/Discriminative Dimensions
Discriminative dimension locates and classifies; affective dimension is the unpleasant, emotional response
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Nociceptor
Receptors that are sensitive to stimuli which are potentially damaging to skin; thermal, mechanical, chemical, “silent”; pain cannot simply be explained by application of nociceptors
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Gate Theory
Proposes that pain signals are modulated in the spinal cord, acting as a “gate” that can either open or close, allowing pain signal to reach the brain and be perceived; influenced by the balance of activity in nerve fibers and emotional and cognitive states
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Phantom Limb
Pain reported in amputated limbs; similar brain response to hypnotically and physically induced pain
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Endorphin
Endogenous brain chemicals modulate pain
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Auditory Perception
Percepts loudness, pitch, timbre
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Pitch
Derived from sound wave frequency; percept associated with sound frequency; metameric percept (like color); the same sensation of pitch can be elicited by very different sounds; sounds separated by an octave perceived similarly (chroma)
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Loudness
Derived from sound wave pressure level; 10dB SPL increase approximately doubles perceived loudness; perceived loudness is measured by comparing two tones and deciding which one is louder, also varies with sound frequency
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Timbre
Derived from sound wave shape; that attribute of auditory sensation in terms of which a listener can judge that two sounds, similarly presented and having same loudness and pitch are different; everything that is not loudness, pitch, or spatial perception; multidimensional percept; related to relative amplitude of harmonics (integer multiples of fundamental frequency) as observed in Power Spectrum
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Sound Pressure Level (SPL)
Pressure waves, vibrations of the molecules of the medium (like air)
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Decibel (dB)
Measure of sound amplitude or of SPL
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Phon
A unit of perceived loudness, distinct from physical decibel measurements
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Frequency
A physical measure of sound oscillation rate
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Hertz (Hz)
Unit for measuring frequency; 1 Hz = 1 oscillation per second
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Outer Ear
Pinna, concha; gather sound energy and focus it via the auditory meatus on the tympanic membrane (eardrum); selectively filter sound frequencies to provide cues about source elevation
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Middle Ear
Role in impedance matching; match low-impedance airborne sounds to higher impedance fluid of the inner ear; pressure boosts up to 200x; 3 ossicles (malleus, incus, stapes)
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Pinna/Concha
Pinna is the funnel-shaped part of the external ear and the concha is the shell-shaped structure, they collect and focus sounds towards auditory canal
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Inner Ear
Contains the cochlea; where pressure waves are transformed into neural signals
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Auditory Meatus/Canal
The passageway that directs sound waves from the outer ear to the eardrum
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Tympanic Membrane (Eardrum)
Membrane that separates the outer ear from the middle ear; transforms the pressure waves of sounds into mechanical vibration of the ossicles
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Impedance Matching
Transference of energy from the air of the middle ear to the inner ear fluid
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Ossicle
The three tiny bones located in the middle ear (stapes, malleus, incus)
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Stapes, Malleus, Incus
Transmit and amplify sound vibrations from the eardrum to the inner ear
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Stirrups, Hammer, Anvil
Relate to the three ossicles; stirrups (stapes), anvil (incus), hammer (malleus)
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Cochlea
A snail-shaped, fluid filled structure in the inner ear that is responsible for converting sound waves into electrical signal that the brain can interpret as sound
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Basilar Membrane
Part of the cochlea that is responsible for separating and encoding different sound frequencies
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Semicircular Canal
Three fluid-filled, looped tubes within the inner ear that are part of the vestibular system, which is responsible for balance and spatial orientation
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Organ of Corti
The sensory organ (equivalent of retina); runs along the whole basilar membrane; contains hair cells with stereocilia (transducers that convert motion into neural signals); start of the auditory nerve
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Inner/Outer Hair Cell
Inner hair cells are sensory receptors that send information to higher cerebral levels, 95% of the fibers in auditory nerve; outer hair cells receive projections from upper cerebral levels
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Auditory Nerve
Responsible for transmitting auditory information from the inner ear to the brain; each nerve fires near peak displacement of the basilar membrane
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Phase Locking
The consistent firing of neurons at a specific phase of a periodic stimulus, like a sound wave; each auditory nerve fiber is tuned to a best frequency
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Frequency Decomposition
Basilar membrane is narrow/stiff at base and wide/flexible at apex; different parts of BM are tuned to different frequencies; frequency decomposition, high frequencies at the base and low frequencies at the apex; topographic organization by frequency preserved up to level of auditory cortex
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Tonotopy
The organized arrangement of neurons in the auditory system based on their response to different frequencies of sound
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Place Model
Posits that different sound frequencies are perceived based on the location where the basilar membrane and the cochlea vibrate the most; the higher the pitch, the closer to the base of the basilar membrane
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Rate Model
Precise timing of individual spikes
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Cochlear Nucleus
Receives all the coded information about sound from the cochlea and is the source of auditory information for the rest of the central auditory system
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Superior Olivary Complex
Collection of brainstem nuclei in the pons; functions in multiple aspects of hearing, important component of the ascending and descending auditory pathways
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Inferior Colliculus
Paired structure in the midbrain, which serves as an important relay point for auditory information as it travels from the inner ear to the auditory cortex
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Medial Geniculate Body
The information bottleneck, in the thalamus, for neural representations of sounds being sent to to auditory cortex
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Auditory Cortex (A1)
Part of the temporal lobe that processes auditory information
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Characteristic Frequency
The frequency of a sound at which the threshold of a single fiber of an auditory nerve is lowest and to which it is therefore most responsive
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Frequency Tuning
The selectivity of neurons to specific sensory stimuli, particularly related to frequency in the auditory system; describes how neurons respond more strongly to certain frequencies which determines pitch perception
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Basic Taste
Sweet/sour/bitter/salty/umami
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Gustation
The sense of taste, the act or process of tasting
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Magnitude Estimation
In a typical experiment, participants are asked to estimate the magnitude of each “basic” taste in a given chemical applied to the tongue
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Taste Bud
Organs on the tongue that have a cluster of taste receptor cells; responsible for detecting and transmitting taste information to the brain
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Papillae
Small bumps or projections on the surface of the tongue that contain taste buds
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Labelled Lines
Posits that quality-specific taste receptor cells synapse only with primary sensory afferents that are dedicated to that same quality
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Taste Receptors Cells
As soon as an appropriate tastant molecule attaches to the receptor the cell depolarizes and sends a signal down one of the gustatory nerves
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Tastant
Glucose, sucrose, fructose (sweet); acids like citric/lemon, acetic/vinegar (sour); sodium chloride (salty); quinine/tonic water, caffeine (bitter); monosodium glutamate (umami)
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Nucleus of the Solitary Tract (NST)
Part of the taste pathway; signals from taste cells travel along different nerves and make connections to the brain stem in the NST which then move to the thalamus
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Insula
Part of the taste pathway; takes signals from the thalamus
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Frontal Operculum
Part of the taste pathway; takes signals from the thalamus; in the frontal lobe
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Orbito-Frontal Cortex (OFC)
Fibers from the taste system also reach the OFC, also receives olfactory signals; first place where taste and smell combine
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Pheromone
A secreted or excreted chemical that triggers a social response in other members of the same species
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Anosmia
The complete inability to detect odors
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Olfaction
The sense of smell, specifically the process of perceiving and identifying odors through the olfactory system
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Detection vs. Identification
Can measure different detection thresholds for different odorant concentrations; recognition threshold normally requires about 3x the concentration compared to simple detection; it’s often easier to detect the presence of a smell when you can give it a name
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Olfactometer
Used to help control air flow and humidity when controlling concentrations in stimulus presentations; device used to present controlled odor stimuli to subjects
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Sniffin’ Sticks
Used to control concentrations is stimulus presentations
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Olfactory Mucosa
Odorants are inhaled and flow over the olfactory mucosa
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Olfactory Receptor Neurone (ORN)
Odorant molecules stimulate the ORNs embedded in the mucosa which produce a neural signal
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Olfactory Nerve
Transmits information about odorants from the nasal cavity to the brain, allowing us to perceive and identify different smells
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Glomerai
Located in the olfactory bulb; receive input from ORNs and act as the first step in processing olfactory signals, where odorant molecules are converted into neuronal activity
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Olfactory Bulb
The brain’s initial processing center for smell information, receiving signals from the olfactory nerve and relaying them to other brain regions
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Pyriform Cortex (PC)
Receives signals from the olfactory bulb and passes them to the OFC
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Amygdala
Receives signals from the olfactory bulb and passes them to the OFC; associated with emotion processing, and may play a role in the emotional reactions that odors often elicit
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Hippocampus
Stores and organizes memories, including those related to smells
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Perceptual Organization
How we are able to segregate odorants in the morning like coffee, bacon, and orange juice (similar to perceiving overlapping objects as separate and individual instruments in an orchestra)
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Olfactory Encoding
Different odorants cause neural activity across a range of olfactory receptor classes, this pattern of activity is thought to underlie olfactory recognition (similar to encoding of color across L, M, S, but there are more types of ORN)
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Bimodal Neurones
Respond to taste and smell, or taste and vision; located in the OFC; some evidence that activity in these neurones reflects the pleasantness of flavors
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Flavor Perception
What we call “taste” is actually “flavor” (combination of gustation and olfaction); deteriorates when the nose is blocked, factors like the burning of peppers can contribute
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Retronasal Route
Odorant molecules released by food travel to the nasal cavity via this route
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Mouth Feel
Contributes to flavor; includes texture, temperature, spiciness, coolness, dryness
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Super Taster/Non-Taster
Supertasters are individuals with a heightened sensitivity to flavors, particularly bitterness, while non-tasters have significantly reduced sensitivity to taste
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Synesthesia
Neurological phenomenon where stimulation of one sense triggers involuntary experiences in another sense
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Gastrophysics
Scientific discipline that focuses on investigations of aspects of gastronomy and cooking that relates to phenomena
