4: Sensation and Perception

Flashcard maker : Lily Taylor
Sensation
our sense organs’ detection of and responses to external stimuli and the transmission of these responses to the brain
Perception
the brain’s processing, organization, and interpretaion of sensory signals, resulting in an internal representation of the stimulus that forms a conscious experience of the world
From Stimulus to Perception:
Sensory Coding
physical properties of stimuli coded into patterns of neural impulses
Transduction
process by which sensory receptors produce neural impulses when they receive physical or chemical stimulation
The Stimuli, Receptors, and Pathways for Each Sense
Qualitative and Quantitative Sensory Information
two types of information that are both necessary for our brain to code and process a stimulus
Qualitative Information
type of information causing our sensory receptors to respond to qualitative differences by firing in different combinations
Quantitative Information
type of information causing our sensory receptors to respond to quantitive differences by firing at different frequencies
Psychophysics
subfield of psychology developed during the 19th century by Ernst Weber and Gustav Fechner, examines our psychological experiences of physical stimuli
Absolute Threshold
minimum intensity of stimulation that must occur before one experiences a sensation
Difference Threshold
the minimum amount of difference required for someone to just barely notice a change in stimuli
Approximate Absolute Sensory Threshold for Each Sense
Weber’s Law
law stating that the just noticeable difference between two stimuli is based on a proportion of the original stimulus rather than on a fixed amount of difference; our ability to perceive a change is directly related to the difference between two stimulus’ average and the change between them
Signal Detection Theory (SDT)
theory of perception based on the idea that the detection of a faint stimulus requires a judgment about the presence or absence of the stimulus based on a subjective interpretation of ambiguous information
Example of Signal Detection Theory
example of this theory, in which a radiologist is looking at a CAT scan for the kind of shadow that signals an early-stage cancer. Her judgement will likely be affected by her knowledge of the patient, training, experience, motivation, attention, and the knowledge of the consequences of being wrong
Signal Detection Research
type of research that involves a series of trials in which a stimulus is presented in only some trials. in each trial, the participant must state whether he or she sensed the stimulus
Hit
term used in signal detection research to describe a trial in which a signal is presented and the observer detects the signal
Miss
term used in signal detection research to describe a trial in which a signal is presented and the observer fails to detect the signal
False Alarm
term used in signal detection research to describe a trial in which a signal is not presented and the observer falsely “detects” the signal
Correct Rejection
term used in signal detection research to describe a trial in which a signal is not presented and the observer correctly does not detect the signal
Response Bias
term referring to a participant’s tendency to report detecting the signal in an ambiguous trial
Payoff Matrices for Signal Detection Theory
Sensory Adaptation
term describing a decrease in sensitivity to a constant level of stimulation; if a stimulus is presented continuously, the responses of the sensory systems that detect it tend to diminish over time; when a continuous stimulus stops, the sensory systems usually respond strongly as well
Gustation
the sense of taste
Taste Buds
sensory organs mostly on the tongue that come in the form of tiny, mushroom shaped structures called papillae which transduce taste information. there are anywhere from 500 to 10,000
Five Basic Qualities of Taste
sweet, sour, salty, bitter, and umami
Umami
taste sensation described as savory or yummy, and is marked by the detection of glutamate, an excitatory neurotransmitter that occurs naturally in foods such as meat, some cheese, and mushrooms
How We Taste
Supertaster
term used to describe someone who has more taste buds than normal and is very sensitive to particular tastes
Olfaction
the sense of smell which has the most direct route to the brain, but may be the least understood sense scientifically partly because the intensity of smell is processed in brain areas also involved in emotion and memory
Olfaction Epithelium
the think layer of tissue, within the nasal cavity, that is embedded with smell receptors
Olfactory Bulb
the brain centre responsible for perceiving the information on smell transmitted by smell receptors which is located below the frontal lobes
How We Smell
Haptic Sense
the sense of touch conveying sensations of temperature, pressure, pain, and where our limbs are in space
Tactile Stimulation
type of stimulation resulting from contact with our skin and giving rising to an integrated experience of touch
How We Experience Touch
Gate Control Theory of Pain
theory stating that for us to experience pain, pain receptors must be activated and a neural “gate in the spinal cord must allow the signals through to the brain
Pain
major part of a warning system that stops you from continuing activities that may cause harm
Fast Nerve Fibers
one of two types of nerve fibers identified with pain, this nerve fiber, characterized by myelinated axons, creates sharp, immediate pain and is activated by strong physical pressure and temperature extremes to lead us to recoil from harmful actions and therefore is protective and/or preventative
Slow Nerve Fibers
one of two types of nerve fibers identified with pain, this nerve fiber, characterized by my nonmyelinated axons, creates dull, steady pain and is activated by chemical changes in tissue when are is damaged to keep us from using the affected body parts and therefore helps in recuperation
How We Experience Pain
Audition
the sense of sound perception resulting from when the movements and vibration of objects cause the displacement of air molecules
Sound Wave
the pattern of changes in air pressure by movements and vibration of objects causes the displacement of air molecules though time which results in the perception of sound
Amplitude
term used to describe the loudness of a sound wave
Frequency
term used to describe the pitch of a sound wave
Hertz
system used to measure a sound’s frequency
Eardrum
a thin membrane stretched across the ear canal which is vibrated by sound waves and marks the beginning of the middle ear
Middle Ear
the air-filled central cavity of the ear behind the eardrum
Ossicles
three tiny bones in the middle ear that are vibrated by the vibration of the eardrum and transfer this vibration to the oval window
Oval Window
membrane located in the beginning of the coclea
Cochlea
a fluid-filled tube that curls into a snail-like shape, containing the basilar membrane, hair cells, and the primary auditory signal
Basilar Membrane
membrane running through the the centre of the cochlea and upon which the hair cells are located
Hair Cells in the Cochlea
the primary auditory receptor; cells located on the basilar membrane that are bent by pressure waves in the cochlea and cause the basilar membrane to fire
How We Hear
Cochlear Implant
hearing aid that works by directly stimulating the auditory nerve in the cochlea, not by amplifying the sound because the sound is picked up by a tiny microphone behind the ear, sent through a computer processor, and then transmitted to the implant’s electrodes inside the cochlea
Auditory Localization
process in which the brain integrates the different timing as well as quantitative and qualitative information coming from each of our two ears
Cornea
the clear out covering of the eye that focuses incoming light in a process called refraction
Retina
the thin inner surface of the back of the eyeball and contains the photoreceptors that transduce light into neural signals
Pupils
the small opening in the eye that lets in and determines how light waves enters the eye
Lens
part of the eye that is bent farther inward after the cornea which focuses the light to form an image on the retina
Rods
retinal cells that respond to low levels of illumination and result in black-and-white perception and are found on the outer edges of the retina
Cones
retinal cells that respond to higher levels of illumination and result in color perception
Fovea
the centre of the retina where cones are densely packed
Photopigments
chemical that initiate the transduction of light waves into electrical neural impulses
Retinal Cells
bipolar, amacrine, and horizontal cells that converge on about a million retinal ganglion cells
Ganglion Cells
the first neurons in the visual pathway with axons, which are gathered into a bundle called the optic nerve
Optic Nerve
nerve which exits the eye at the back of the retina and has no rods or cones which results in a blind spot in each eye
Optic Chiasm
the x-shaped structure formed at the point below the brain where the two optic nerves cross over each other and half of the axons in the optic nerves cross
Lateral Inhibition
a visual process in which adjacent photoreceptors tend to inhibit one another
Three Dimensions of Color
hue, saturation, and brightness
Subtractive Color Mixing
a way to produce a given spectral patter in which the mixture occurs within the stimulus itself (usually pigments) and is actually a physical, not psychological, process and the physical mixing of colors makes the colors absorb (subtract) each other’s wavelengths. the resulting color we see corresponds to the wavelengths that are “left over”
Subtractive Primary Colors
red, yellow, and blue, because together these pigments absorb nearly all the colors of the visible spectrum and when mixed, produce almost black
Additive Color Mixing
a way to produce a given spectral pattern in which different wavelengths of light are mixed. The perception is determined by the interaction of these wavelengths with receptors in the eye and is a psychological process
Additive Primary Colors
red, green, and blue, because mixing these colored lights wields white light
Opponent-Process Theory
theory that different types of ganglion cells, working in opposing pairs, create the perception of opposite colors
Trichromatic Theory
theory stating that there are three types of retinal cone cells that each respond best to a different wavelength of light called “S” (short wavelengths most sensitive to blue light), “M” (medium wavelengths most sensitive to yellow-green light), and “L” (long wavelengths most sensitive to red lights), therefore our perception of colors is determined by ratio of activity among the three types of cone receptors
Kinesthetic Sense
perception of the body’s position in space and movements of our bodies and our limbs by gathering information from receptors in muscles, tendons, and joints (some include this with the sense of touch)
Vestibular Sense
perception of balance gained by information from receptors in the semicircular canals of the inner ear
Primary Sense Regions
Primary Auditory Cortex (A1)
cortex to which all auditory neurons in the thalamus extend their axons to code the frequency of auditory stimuli
Primary Somatosensory Cortex (S1)
cortex to which all tactile neurons in the thalamus project their axons
Primary Visual Cortex (V1)
cortex in the occipital lobe responsible for processing visual information, yet up to half of this part of the brain may participate in visual perception
Visual Areas Beyond V1
areas of the brain containing neurons that appear to process specific aspects of a visual stimulus and categorized in one of two processing streams: either the ventral or dorsal stream
Ventral Stream
one of two processing streams that appears to be specialized for determining “what” an object is by perceiving and recognizing objects, such as determining their shapes and colors
Object Agnosia
neurological disorder characterized by the inability to recognize objects. sufferers cannot identify an object but could draw it from memory
Dorsal Stream
one of two processing streams that appears to be specialized for determining “where” an object is and relating it to others in a scene
Blindsight
a condition in which people who are blind have some some visual capacities in the absence of any visual awareness
Illusions
an image that deceives the visual senses by showing how our brains try to make something two-dimensional instead three-dimensional, and interpret something static as moving and is therefore believed by psychologists to reveal the operations of the mechanisms that help our visual systems determine the sizes and distances of objects in the visual environment
Gestalt Principles
series of laws to explain how our brains group the perceived features of a visual scene into organized wholes
Principle of Proximity
Gestalt law stating that the closer two figures are to each other, the more likely we are to group them and see them as part of the same object
Principle of Similarity
Gestalt law stating that we tend to group figures according to how closely the resemble each other, whether in shape, color, or organization
Principle of Good Continuation
Gestalt law stating that we tend to interpret intersecting lines as continuous rather than as changing direction radically
Occluder
anything that hides a portion of an object or an entire object from view, which is visually reconciled by the good continuation principle by completing an object behind the obstructed view
Principle of Closure
Gestalt law stating that we tend to complete figures that have gaps
Principle of Illusory Contours
Gestalt law stating that we sometimes perceive contours and cues to depth even though they do not exist
Figure vs. Ground
one of the most basic visual organizing principles, and example of which is the figure illusion where the background and the object switch back and forth but cannot exist simultaneously because the brain cannot identify which is which
Bottom-Up Processing
a hierarchical model of pattern recognition in which data are delayed from one processing level to the next, always moving to a higher level of processing
Top-Down Processing
a hierarchical model of pattern recognition in which information at higher levels of processing can also influence lower, “earlier” levels in the processing hierarchy
Example of the Importance of Context in Object Recognition
Prosopagnosia
neurological deficits in the ability to recognize faces
Fusiform Gyrus
area of the brain thought to be specialized for facial recognition
Binocular Depth Cues
cues of depth perception that arise from the fact that people have two eyes and contribute to bottom-up processing
Stereoscopic Vision
the ability to determine an object’s depth based on that object’s projections to each eye
Binocular Disparity
a cue of depth perception that is caused by the distance between a person’s eyes, creating two slightly different views of the world which the brain can use to compute distances to nearby objects
Monocular Depth Cues
cues of depth perception that are available to each eye alone for top-down processing
Pictorial Depth Cues
Motion Parallax
cues from the relative moment of objects that are at various distances from the observer used by the brain to determine depth perception
Example of Motion Parallax
example where as you move, nearby objects pass quickly in your opposite direction while intermediate objects pass more slowly in the opposite direction of the nearby object, and farther away objects appear to match your speed moving in the same direction relative to the intermediate-distance object
Size Perception Depends of Distance Perception
relationship stating that the size of an object’s retinal image depends on that object’s distance from the observer
Ames Box
optical illusion in which a diagonally cut room appears rectangular by using cooked windows and floor tiles so that when one child stands in a near corner and another (of similar height) stands in a far corner, the room creates the illusion that they are equidistant from the viewer; therefore, the closer child looks like a chi ant compared to the farther child
Ponzo Illusion
optical illusion caused by monocular depth cues that make the two-dimensional figure seem three-dimensional. as the parallel lines appear to converge in the distance, the top line looks farther away and therefore smaller, when in reality they are the same size, which shows how much the brain defaults to using depth cues even when depth is absent
Three Phenomena on How the Visual System Perceives Motion
motion after-effects, compensation for head and eye motion, and stroboscopic motion perception
Waterfall Effect
effect describing what happens if you stare at a waterfall and then turn away, the scenery you are no looking at will seem to move upward for a moment because when you stare at a moving stimulus long enough, these direction-specific neurons adapt to the motion and become fatigued and when the stimulus is removed, other motion detectors that respond to all other directions are more active than the fatigued motion detectors
Compensation for Head and Eye Movement
phenomenon that answers the question: when you see what appears to be a moving object, how do you know whether the object is moving, you are moving, or your eyes are moving?
Image Movement System
one of two ways in which the visual system detects movement
Eye Movement System
one of two ways in which the visual system detects movement
Stroboscopic Movement
a perceptual illusion that occurs when two or more slightly different images are presented in rapid succession
Phi Movement
phenomenon in which when two vertical lines are placed close together at intervals the lines appears to move continuously as one line with no breaks
Perceptual Constancy
term describing the tendency for the brain to correctly perceive objects as constant despite sensory data that could mislead perception
Size Constancy
perception of an object obtained by understanding our distance from an object
Shape Constancy
perception of an object obtained by understanding the angle to which we see the object
Color Constancy
perception of an object obtained by understanding the wavelengths of light reflected from the object with those reflected from wits background
Lightness Constancy
perception of an object obtained by understanding how much light is being reflected from the object and from its background
Relative Magnitude
ratio used by perceptual systems to understand an object based on detecting changes from baseline condition and not just responding to sensory outputs

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