Sensation and Perception Flashcards
Response Bias
tendency of subjects to respond in a particular way due to non-sensory factors
Smell
- also comical sense (molecules of stimulus actually have to come in contact with receptors)
- receptors: located in olfactory epithelium (upper part of nasal passage)
- smell travels to olfactory bulb in the brain which is connected to amygdala and hippocampus which is why smell is connected to memory
Wever and Bray
Proposed volley theory of pitch perception in response to criticism of the frequency theory of perception
iris
- colored part of the eye
- has involuntary muscles and nerve fibers
- controls the pupil (and therefore the amount of light entering the eye)
Figure vs. Ground
- Figure: object that stands out at the center of attention in the visual field
- Ground: the background
- they can change! (ex: face vase illusion)
Vestibular Sense
- has to do with our sense of balance and bodily position relative to gravity
- semicircular canals in inner ear (above and behind cochlea) hold receptors for balance
Habituation
- research method for studying visual perception in infants
- a stimulus is presented to an infant and they eventually stop attending to it; a different stimulus is presented and if the infant attends to it, then it is inferred that the infant can perceive the difference between the two stimuli
Auto-kinetic Effect
- when viewed in a dark room, a stationary point of light appears to move, probably because of involuntary eye movements
Proprioception
- general term for our sense of bodily position; includes aspects of both vestibular and kinesthetic senses
E. Gibson and Walk
Developed the visual cliff apparatus, which is used to study the development of depth perception (experiments done on infants and animals)
Signal Detection Theory
- suggests that other, non sensory factors influence what we sense (factors include things like experiences, motives, and expectations)
- gives us a way to measure both how well subjects can sense stimuli (sensitivity) and response bias
- basic signal detection experiment: stimulus is either presented or it isn’t. Trials where it is NOT presented are called noise trials (or catch trials); trials where it is presented are called signal trials. Subject is asked to indicate whether or not a stimulus is presented.
- Four possible outcomes: Hits (++), Misses (+-), False Alarms (-+), and Correct Negatives (–)
- responses are graphically summarized by ROCs
Touch
- four broad categories: pressure, pain, warmth and cold
- at least 5 different tyoes of receptors:
1) Pacinian Corpuscles (displacement of skin such as deep pressure or vibration)
2) Messiner Cospuscles
3) Merkel Discs
4) Ruffini Endings
5) Free nerve endings - information processed in somatosensory cortex in parietal lobe
Trichromatic Theory
- aka Young-Helmholtz Theory
- suggests that the retina contains three different kinds of cones (color receptors), each of which is maximally sensitive to one of the three primary colors (green, blue, or red)
- light hits the retina and these three types of cones are stimulated to varying degrees. it is the RATIO of this activity that determines color.
- Young showed that you could mix the three primary colors and produce all of the other colors on the spectrum
- EXTRA Q: Where else do we see Helmholtz?
- developed place resonance theory of pitch perception
Distal vs. Proximal Stimulus
- distal: actual object or event out there in the world
- proximal: information our sensory receptors receive about the object
Fechner’s Law
- derived from Weber’s Law
- purpose: to relate the intensity of the stimulus to the intensity of sensation.
- determined that sensation increases more slowly as intensity increases
Gate Theory of Pain
- Melzack and Wall
- theory that there is a gating mechanism in the spinal cord that turns pain signals on and off
Shape constancy
- tendency for the perceived shape to remain constant regardless of variations in the retinal image
- ex: we see a door as rectangular even when as we open and close a door its retinal image can be anywhere between a line and a trapezoid
Moon Illusion
- also has to do with size constancy
- the moon looks bigger when on the horizon then when up in the sky (at its zenith*) despite the fact that the moon is the same size in both scendarios
- because on the horizon we have things to compare it too but we dont in the sky (relative size to buildings / etc. vs. to the blank sky)
temporal fibers
- fibers from temporal half of retina (away from the nose, closer to the temples)
- these do not cross over
ciliary muscles
- control the lens, allow it to accommodate in order to focus an image on the retina
Four Visual Constancies
- size constancy: tendency for the perceived size of an object to remain constant despite variations in the size of its retinal image
- shape constancy: tendency for the perceived shape of an object to remain constant despite variations in the shape of its retinal image
- lightness constancy: tendency for the perceived lightness of an object to remain constant despite changes in illumination
- color constancy: tendency for the perceived color of an object to remain constant despite changes in the spectrum of light falling on it
Taste
- chemical sense; molecules of stimulus actually have to come in contact with receptors
- receptors are tastebuds held in the papillae (little bumps on the tongue)
- information is sent to taste center in thalamus
Photoreceptor cells
- rods and cones
- responsible for sensory transduction through the chemical alteration of photopigments
Gestalt laws of perception:
1) Proximity: elements close to one another tend to be perceived as a unit
2) Similarity: objects that are similar tend to be grouped together
3) Good Continuation: tend to perceive continuous patterns in stimuli rather than abrupt changes
4) Closure: tend to be perceive figures as complete, and will even fill in gaps / perceive figures as more complete (or closed) then they really are
5) Prägnaz: encompasses the other laws; says that perceptual organization will always be as regular, simple, and symmetric as possible.
Cocktail Party Phenomenon
- you could be having a conversation with someone and totally tuned in but still hear your name from across the room in another conversation
Hering
Developed opponent process theory of color vision
J. Gibson
Studied depth cues (specifically texture gradients) that help us to perceive depth
Receiver Operating Characteristic (ROC) curve
- used to graphically summarize a subject’s responses in a signal detection experiment
- refined by Swets
Emmert’s Law
- describes the relationship between size constancy and apparent distance
- later generalized into size-distance invariance principle
- says that size constancy depends on apparent distance. the farther away an object appears to be, the more the scaling device in the brain will compensate for its retinal size by enlarging our perception of the object
Broadbent
Proposed filter of attention theory which argued that attention was an all-or-nothing process (which has now been proven to be incorrect)
Binocular Disparity
- binocular depth cue (requires both eyes)
- distance between the two eyes make our eyes see slightly different pictures of the world, degree of disparity between the two eyes is called binocular parallax
- when our brain combines these two images we get STEREOPSIS
- 10% of the population cant take advantage of this so rely on monocular depth cues
- use stereoscopes (tool) to research this (give impression of depth to a flat picture by presenting the eye with slightly different images like they would get in 3D)
Fovea
- mid section of the retina, contains only cones
- as you move farther away from retina, number of rods increases and number of cones decreases
- most sensitive in normal daylight vision
- visual acuity is best here
Duplexity (or duplicity) theory of vision
- states that the retina has two kinds of photoreceptors (rods and cones)
Single-cell recording
- used by Hubel and Wiesel to measure cell responses for Feature Detection Theory
- method involves placing a microelectrode (so small that the tip cannot be seen with an ordinary microscope) in the cortex so sensitive that it could record responses of a single cell.
- sometimes called “recording from single nerve fibers”
Light is composed of:
photons and waves; measured by brightness and wavelengths
Theory of Isomorphism
- suggests 1-to-1 correspondence between the object in the perceptual field and the pattern of stimulation in the brain
- hasn’t fared well empirically but sometimes appears on the test
Important factors in Brightness Perception:
- (dark) adaptation: regeneration of rhodopsin in rods (from bleaching), allowing you to see better in darkness. takes time, which is why it takes a second to adapt to a dark room such as a movie theater.
- lateral inhibition: adjacent retinal cells inhibit one another; sharpens and highlights borders between light and dark areas
Illumination vs. Brightness
Illumination is a physical, objective measurement that is simple the amount of light falling on a surface. Brightness is the subjective impression of the intensity of light stimulus.
Auditory Projection areas in the Brain:
- superior olivary complex
- inferior colliculus
- medial geniculate nucleus (in thalamus)
- temporal cortex
Projection Areas
brain areas that further analyze sensory input
cornea
- clear protective coating on outside of the eye
- gathers and focuses incoming light
Difference Threshold
how different two stimuli must be (in magnitude) before they are perceived as different
related to JND
Physiological 0
- a neutral temperature of skin perceived to be neither cold nor hot
standard vs. comparison stimulus
compare to find difference threshold
standard: first stimulus
comparison: second stimulus
brain areas important for processing visual information:
- lateral geniculate nucleus (thalamus)
- visual cortex (occipital lobe)
- superior colliculus
Stevens’ Power Law
Stevens’ suggested that Fechner’s law may be incorrect, so created another equation (this law) that also relates intensity of the stimulus to the intensity of sensation
Helmholtz
Developed place-resonance theory of pitch perception and, along with Young, the Young-Helmholtz trichromatic theory of color vision
Traveling Wave Theory
- Békésky
- basilar membrane vibrates together but movement is maximal at different parts of the membrane for different frequencies (higher frequencies closer to oval window, lower frequencies closer to tip of cochlea)
- also found that very low frequencies (> 400 Hz) maximally vibrated a very broad part of the membrane
lens
- located behind the iris
- helps control the curvature of light coming in and can focus near or distant objects on the retina (called accommodation)
- controlled by ciliary muscles
Inner Ear
- Oval window: gateway to inner ear
- Cochlea: looks like a snail shell; filled with cochlear fluid
- Basiliar membrane: runs the length of the cochlea, organ of corti rests on top of it
- Organ of Corti: tiny hair cells that are the receptors for hearing. when they bend, transduction happens and these signals are sent out of the cochlea on nerve fibers to the auditory nerve
Monocular Depth Cues
Monocular –> needs only one eye
1) Interposition (aka overlap): object A overlaps w/ object B; we perceive object A to be in front of object B
- founded by Berkeley
2) Relative Size: as you move farther away from an object, its image gets smaller on the retina, so the size is perceived to be smaller.
- founded by Berkeley
3) Linear Perspective: convergence of parallel lines in the distance
- founded by Berkeley
4) Texture Gradient: textures will seemed more blurred together / less detailed the farther away you are from them
- founded by JJ Gibson
5) Motion Parallax: when observer moves, objects in a stationary environment appear to move in the same direction as the observer
- Kinetic Depth effect: when object rather than perceiver moves
Cones
- used for color vision and for perceiving fine detail
- most effective in bright light
- allow us to see chromatic and achromatic colors
- concentrated at the center of the retina in the fovea
- see better than rods because there are fewer cones per ganglion cell than rods per ganglion cell
pupil
- hole in the iris
- contracts / expands in order to let in more / less light
Objective Dimensions of Sound
- Frequency: number of cycles per second; measured in Hertz (Hz)
- Intensity: the amplitude of the sound wave; measured in decibels (tenths of a bel)
Fechner
Built upon Weber’s Law and developed Fechner’s Law, which expresses the relationship between the intensity of the stimulus and the intensity of the sensation
Absolute Threshold
minimum of stimulus energy needed to activate a sensory system (at least 50% of the time)
Kinesthetic sense
- awareness of body movement and position
- receptors are at or near muscles and joints
Dichotic listening
- technique used to study selective attention in the lab
- two ears are simultaneously presented with different stimuli, subject is asked to shadow (repeat one of the messages presented)
- shows that observes can indeed attend to one message and damped the other
Bottom-Up processing
- data-driven processing
- responds directly to components of incoming stimulus and then sums up components to arrive at the whole pattern
Retina
- located on the back of the eye
- receives light images from the lens (inverted and upside down)
- composed of ~132 million photoreceptor cells and of other cell layers that process information
Steps of sensory information processing and explanation of each
1) Reception (receptors react to physical external stimulus energy)
2) Transduction (translation of physical energy into neural impulses or action potentials)
3) Electrochemical energy is sent to various projection areas in the brain along various neural pathways to be processed by the nervous system
Afterimages
- visual sensation that appears after prolonged or intense exposure to a stimulus
- ex: if you stare at a red square for several minutes and then transfer your gage to a white piece of paper, you will see a green square
- have been used to support Hering’s opponent process theory
Lateral Inhibition
- important factor in brightness perception
- explains simultaneous brightness contrast (the idea that a target area appears brighter when surrounded by a darker stimulus than when surrounded by a lighter stimulus)
- basically, if a cell is excited, neighboring cells will be inhibited, therefore they do not fire as often, and then their corresponding area does not appear as bright.
- this is important because is sharpens and highlights borders between dark and light areas
Brightness
physical intensity of light
Animal Experiments for Visual Perception
- unethical to deprive newborn babies of visual stimuli so we do it to mice
- most find that experience plays an important role in development of visual system and that there is a sensitive period during which this experience is maximally effective
nasal fibers
- fibers from nasal half of the retina (closer to the nose)
- these cross paths at the optic chiasm
Opponent-process theory of color vision
- Hering’s criticism of trichromatic theory
- says that yellow is also a primary color, and that the FOUR primaries (green, blue, red, AND yellow) were arranged in opposing pairs: red/green and blue/yellow.
- also included one more opposing pair to code brightness: black/white
- essentially, one color (ex: red) excites the cell and the other (ex: green) inhibits the cell, and because a cell cant be both excited and inhibited at the same time, you would never have a greenish-red.
- AFTERIMAGES support this theory
- modern research shows that this theory applies to other cells in the visual system (ex: cells in the lateral geniculate nucleus) while trichromatic theory was right about the three different kinds of cones.
Two-point threshold
The minimum distance necessary between two points of stimulation on the skin such that the points will be felt as two distinct stimuli
Lightness constancy
- tendency for perceived lightness to remain the same despite changes in illumination
- this occurs because levels of ilumination for both the object and the background remain the same
- ex: when the sun goes behind dark clouds, a sail on a sailboat still remains bright white instead of dimming to gray
- has to do will illumination / brightness while color constancy has to do with wavelengths of light
Berkeley
Developed a list of depth cues that help us to perceive depth (specifically interposition, relative size, and linear perspective)
Yerkes Dodson Law
- performance is at its worst at extremely high or extremely low levels of arousal, best performance is at moderate level of arousal
just noticeable difference (JND)
measure the same thing as difference threshold but in different units
EX: if 2 ounces is how much is necessary to notice a difference in weight, then 1 JND = 2 ounces; 2 JND = 4 ounces; etc.
Place- Resonance Theory
- Helmholtz
- different pitches cause different parts of basilar membrane to vibrate which is why we hear distinctions in pitch
Visual angle
- determines the size of the image on the retina
- determined by size of object and distance between the object and the eye
- helps explain size constancy
Middle Ear
- Eardrum acts as a gateway to Ossicles
- Ossicles: smallest bones in the body; submit vibrations from eardrum to inner ear
1) Hammer (malleus)
2) Anvil (Incus)
3) Stirrup (stapes) - edge of Stirrup rests on Oval Window, which is the gateway to the inner ear
Rods
- particularly sensitive to dim light; used for night vision
- concentrated along the sides of the retina (so are extremely important for peripheral vision)
- allow perception only of achromatic colors (not used in color vision)
- low sensitivity to detail
- many more rods than cones in the human eye
Frequency Theory
- basilar membrane vibrates as a whole; rate of vibration equals frequency of stimulus. This vibration rate is directly translated into appropriate number of neural impulses (ex: 500 Hz = 500 impulses per second), so pitch is determined by frequency of impulses traveling up the nerve
- cannot be applied above 1000 Hz so Wever and Bray modified the theory by adding the Volley Principle (states that high rates of neural firing can be maintained if nerve fibers work together)
Hubel and Wiesel
Studied feature detection in the visual cortex and discovered simple, complex, and hypercomplex cells
Stevens
Developed Stevens’ power law as an alternative to Fechner’s law
Optic Array
all the things person sees; trains people to perceive
Motion aftereffect
- if a moving object is viewed for an extended period of time, it will appear to move in an opposite direction when the motion stops
Subjective Dimensions of Sound
- Pitch: subjective experience of the frequency of sound
- Loudness: subjective experience of intensity of sound
- Timbre: refers to quality of sound; related to the complexity of the wave or the mixture of the frequencies
- ex: same note (same pitch / loudness) played on a clarinet sounds different then the played on the piano
Color Perception
- related to the wavelength of light entering the eye
- human eye can see wavelengths from ~ 400 - ~ 800 nanometers
- if a stimulus does not emit its own light, we perceive it by processing the light reflected off of it. An apple appears red because the wavelengths that appear red to us are reflected by the apple while all the other wavelengths are absorbed.
Subjective contours
- perceiving contours and therefore shapers that are not present in physical stimulus
- some researchers argue this phenomena arises from law of good continuation
Hue
- also known as color
- dominant wavelength of light
Outer Ear
- Pinna: outer, fleshy part of the ear who’s main function is to channel sound waves into the auditory canal
- Auditory Canal: channels sound to the eardrum
- Eardrum: also called Tympanic Membrane; is the gateway to the middle ear. Vibrates in phase with the incoming sound waves and sends those vibrations to ossicles.
Top-down processing
- conceptually driven processing
- guided by conceptual processes such as memories and expectations that allow the brain to recognize whole objects and then the components
Feature detection theory
- Hubel and Wiesel
- suggests certain cells in the cortex are maximally sensitive to certain features of stimuli
- used single-cell recording to measure cell responses
- three different types of cells:
- simple: responds to info about orientation / boundaries of an object
- complex: responds to more advanced info like movement
- hypercomplex: respond to more abstract concepts like shape
Köhler
Developed the theory of isomorphism (which suggests one-to-one correspondence between object in the perceptual field and the pattern of stimulation in the brain). This theory hasn’t fared well empirically but has appeared on the GRE anyways.
Apparent motion / Phi phenomenon
- also called phi phenomenon
- when two or more stationary lights flicker in succession, they tend to be perceived as a single moving light
Ames Room
- room is very much not a normal rectangular room but looks like it when you look through a peep hole so can distort depth perception (think: that room in the illusion museum where people the same height look drastically different heights)
- relates to size constancy and Emmert’s law (because apparent distance is closer / farther than actual distance which distorts image)
Induced motion
- stationary point of light appears to move when the background moves
Preferential Looking
- research method for studying visual perception in infants
- designed by Fantz
- two different stimuli are presented side by side; if infant looks longer at one of them, it is inferred that the infant can perceive the difference between the stimuli
layers of neurons between receptors and optic nerve
- information travels to horizontal cells to bipolar cells to amacrine cells to ganglion cells
- ganglion cells group together to form the optic nerve
- each ganglion cell represents combined activity of many receptors (the more receptors per ganglion cell = more difficulty in making out fine details)
Color constancy
tendency of a perceived object to remain the same color despite changes in the spectrum of light falling on it
- ex: when you put on amber sunglasses, you still know what colors things are
Visual Cliff
- designed by Gibson and Walk
- an apparatus to assess infant depth perception
- there is a clear glass slate over the illusion of a cliff and infants as young as 6 months won’t cross it to see their mom because they see the depth
Swets
Refined ROC curves in signal detection theory
Selective Attention
- Broadbent said that selective attention acts as a filter between sensory stimuli and our processing systems
- He said it was all or nothing which has since been proven false
optic chiasm
- nasal fibers cross paths and join the optic nerve from the other eye
- ensures that input from each eye will come together for a full picture of the brain
- therefore, stimulus in the left visual field is processed in the right side of the brain and vice versa
Békésky
Research led to traveling wave theory of pitch perception which partially supported Helmholtz’s place-resonance theory
Yerkes and Dodson
Developed Yerkes-Dodson Law which states that performance is best at intermediate levels of arousal (but what constitutes intermediate levels of arousal is also dependent on the difficulty of the task at hand)
Sensitivity
measures how well a subject can sense the stimulus
Weber’s Law
? I / I = K
where ? I = delta I
K = Weber’s constant
what’s important in producing a JND is not the absolute difference between the two stimuli but the ratio of them
Subtractive vs. Additive Color Mixtures
- Subtractive: occurs when we mix pigments. Think art class and finger painting. Color combos we think of off the bat are subtractive (ex: blue + yellow = green)
- Primary Colors: Yellow, Blue, Red
- Additive: has to do with / how our eyes see lights.
- Primary Colors: Green, Blue, Red
- ex: if you were to mix red and green lights, you would get yellow. (to remember: think of a stoplight. What is in-between red and green? yellow!)
Melzack and Wall
Proposed gate theory of pain
