Sensation and Perception Psychology Flashcards
Ernst Weber
Published De Tactu which introduced Just Noticeable Differences in sensation.
Wertheimer
Founded Gestalt Psychology
Absolute Thresholds
The minimum of stimulus energy needed to activate a sensory system.
Limen
Another word for threshold.
i.e. subLIMINAL perception means perception below the threshold of conscious awareness.
Difference Thresholds
How different two stimuli must be in magnitude before they can be perceived to be different.
Just Noticeable Difference (JND)
The amount of change necessary to predict the difference between two stimuli.
Weber’s Law
The change in stimulus intensity needed to produce a JND divided by the stimulus intensity of the standard stimulus is constant. Sometimes referred to as Weber’s Fraction/Weber’s Constant.
Fechner’s Law
Expresses the relationship between the intensity of the sensation and the intensity of the stimulus. Generally finds that sensation increases more slowly than intensity.
Steven’s Power Law
Disproves Fechner’s law and replaces it with a new theory regarding how sensation and intensity interact.
Signal Detection Theory
Suggests that there are other nonsensory factors which influence what the subject says they sense (i.e. if they’re overly cautious).
Response Bias
The tendency of subjects to respond in a particular way due to nonsensory factors.
Receiver Operating Characteristic (ROC)
Curves which researchers use to summarize a subject’s response by measuring the sensitivity characteristics of a subject receiving signals.
John A Swets
Refined the use of ROC curves.
Steps to Sensory Info Processing
Reception
Transduction
Sent to projection areas/Processed by nervous system
Transduction
The translation of physical energy into the neuro impulses or action potentials
Parts of the Eye
Cornea- clear dome window gathers and focuses light
Pupil- hole in iris which contracts in light/expands in dim
Iris- colored part of eye, controls light entering eye through pupil
Lens- behind the iris, controls the curvature of light and focuses retina
Retina- screen filled w neural elements (image detecting)
Fovea- middle of retina with only cones. Best visual acuity.
Rods v Cones
Cones = color vision, fine details. most effective in bright light, allow us to see chromatic and achromatic colors
Rods = perceive achromatic colors, most effective in dim light, low sensitivity to details, no color vision.
Connection of cells in eyes
Rods/Cones connect to bipolar neurons
Bipolar neurons connect to ganglion cells
Ganglion cells group together to become optic nerve
Ratio of ganglion to cones much smaller than to rods, which is why cones are better at details.
Optic Chiasm
place where the fibers from the nasal half of retina cross paths (but not the fibers from the temporal fibers). Leads to all info from left visual field going right hemisphere and visa versa.
Where Optic Chiasm info goes
Lateral Geniculate Nucleus (in thallamus)
Visual Cortex in Occipital Lobe
Superior Colliculus
Hubel and Wiesel
Found the neural basis for feature detection theory.
Feature Detection Theory
Suggests that certain cells in the cortex are maximally sensitive to certain features of stimuli.
Three types of cells for feature detection
Simple - respond to orientation
Complex- respond to movement
Hypercomplex- respond to shape
Illumination v Brightness
Illumination - physical/objective measurement of the amount of light on a surface
Brightness - subjective impression of the intensity of light.
Factors in how we perceive Brightness
Adaption - When you become accustomed to the environment and see better
Photopigment
When the rods have a photochemical called rhodopsin
Rohodopsin
Made up of Vitamin A derivative, called retinal, and opsin (a protein).
Bleaching
When rhodopsin absorbs light, the pigment decomposes, (splits into retinene and opsin). Once you’re in the dark, the pigments regenerate leading to you seeing better and adapting to the dark. Vitamin A is crucial in this process.
Simultaneous Brightness Contrast
Target Area of a particular luminance appears brighter if surrounded by darker stimulus. Explained by lateral inhibition.
Lateral Inhibition.
When adjacent retinal cells inhibit eachother. If one cell is excited, the neighboring cells are inhibited. This leads to simultaneous brightness contrast and helps us to sharpen the borders between light and dark areas.
Opponent-Process Theory
Developed by Hering to criticize trichromatic theory. Suggests there were 3 opposing pairs, which signal the presence of colors which signal what the eye is seeing. The pairs were: red-green, blue-yellow, and black-white.
This theory implies you can never see a color mix of opposing pairs (ie a red-green).
Later found to be incorrect in direct vision, but applies to cells in the lateral geniculate nucleus.
Young-Helmholtz Theory
AKA: the trichromatic theory. Suggests that there are three different types of color receptors (cones), which are differentially sensitive (one to red, one to blue, and one green). Proposes that all colors are produced by combining the varying stimulation of these receptors.
Found to be correct later when there were better methods to analyze this.
Afterimages
Inspired Hering’s Theory. True in multiple things (color, motion, etc). When you have prolonged/intense exposure to a stimulus, then look at something blank, you see an afterimage of the “opposite” of the original stimuli.
George Berkeley
In 1700s, listed the various cues for depth and explained how we see depth from the 2-dimensional retina. Proposed: interposition, relative size, and linear perspective.
Depth Cue: Interposition
AKA overlap. Refers to when one object covers/overlaps with another so we see object on top as being in front and closer.
Depth Cue: Relative Size
We can tell how far something is from the relative size of various items on the retina (the father away something is, the smaller it is)
Depth Cue: Linear Perspective
The convergence of parallel lines in the distance (the appearance that parallel lines converge at the horizon). Since we know they don’t actually converge, we use how close they look to be how far they are.
Depth Cue: Texture Gradients
Comes from work of Gibson. The variations in perceived texture as a function of distance. Generally, the more distant something is, the smaller and more packed the elements are. Additionally sudden changes occur at corners or other changes in direction/distance.
Depth Cue: Motion Parallax
Objects closer to you than your fixation point appear to move in the same direction as you are. The speed of those items varies based on how close they are to your fixation point.
Depth Cue: Kinetic Depth Effect
Part of motion parallax when the objects are moving and not the perceiver. The relative speed of the items give us cues to how far it is.
Depth Cue: Stereopsis
AKA binocular disparity. The slight differences in location of our eyes leads to slight differences in our vision which gives us cues to location and depth. Depends on the binocular parallax (which is the fact that we see slightly different from both eyes).
Called a binocular depth cue since requires two eyes.
Two concepts of Form Perception
Figure and ground.
Figure is what stands out as center of attention. Ground is the background.
Gestalt Laws of Organization
Laws which explain form perception proximity similarity good continuation subjective contours closure
Law of proximity
Items close to each other are perceived as a unit.
Law of Similarity
Objects that are similar tend to be grouped together.
Law of Good Continuation
Elements that appear to follow the same direction tend to be grouped together. We like to see continuous patterns and not abrupt changes.
Law of Subjective Contours
Figures often appear more complete/closed then they actually are based upon the information surrounding it.
Law of Closure
Even if lines are not complete we perceive them as so
Law of Prägnanz
Encompasses all the gestalt laws of organization- saying that perceptual organization will always be as “good” as possible- as regular, simple, and symmetric as possible.
Theory of Isomorphism
Proposed by Kohler. Suggests there is a 1-1 correspondence between the objects in the perceptual field and the pattern of stimulation in the brain.
Not empirically based.
Bottom-Up Processing
Data driven processing. object perception that responds directly to the components of incoming stimulus on the basis of fixed rules. Then sums up the components to find the whole pattern and detect the features.
Top-Down Processing
Conceptually Driven Processing. Refers to object perception that is guided by conceptual processes such as memories/expectations. Allows us to recognize the whole object, and then notice the components.
Types of Motion Perception
Real Motion Apparent Motion Induced Motion Autokinetic Effect Motion Aftereffect
Real Motion
When we perceive light that is actually moving.
Apparent Motion
The illusion that occurs when two dots flashed in different locations seconds apart appear to be one moving dot.
Induced Motion
The illusion of movement occurring when everything around the spot of light is moved.
Autokinetic Effect
The illusion that occurs when a stationary spot of light appears to move erratically in the dark room, because there is no frame of reference.
Motion Aftereffect
When you view a moving pattern, then look at the spot of light, it will appear to move in the opposite direction. Aka the waterfall illusion.
Proximal vs Distal Stimuli
Distal Stimulus: the actual object in the world
Proximal Stimulus: the information our sensory receptors receive on the object
The Four Major Constancies in Vision
Size
Shape
Lightness
Color
(So She Likes Color?)
Size Constancy
Visual angles help us determine the size of objects. Constancy and distance is described by Emmert’s Law
Emmert’s Law
AKA: The Size-Distance Invariance Principle. The size constancy depends on apparent distance. The father away the object appears to be, the more the scaling device in the brain will compensate for retinal size by enlarging our perception of the object.
Ames Room and the Moon Illusion
Illusions which demonstrate Emmert’s Law.
Ames room is a constructed room which makes it so people appear to be different sizes, but it’s just do to the perception they’re standing next to eachother and not far apart.
Moon Illusion is that it looks bigger on the horizon then in the sky. This is due to the distance cues like buildings, which make it appear larger.
Shape Constancy
We see shapes as constant, even if the retinal image changes (ie if we open a door, we still see it as a rectangle, even though the retinal image is of a trapezoid).
Lightness Constancy
Despite changes in the light falling on an object, the apparent lightness of the object remains unchanged. This occurs because the levels of illumination are the same for both objects and the backgrounds.
Color Constancy
The perceived color of an object does not change when we change the wavelength of the light we see.
Common Visual Illusions
Muller-Lyer: lines w arrows on ends
Hering: parallel lines with background circle (look malformed)
Ponzo: equi-lengthed lines in a triangle look different sizes
Wundt: similar to Hering
Poggendorff: diagonal line is blocked from view, looks separate but is actually straight.
Reversible Figures: stimulus patterns in which two perceptions are accurate (AKA necker cube)
Methods for studying infant visual perception
Preferential Looking: seeing if/how long the infant looks at multiple items to see what they prefer (generally complex and social images are preferred)
Habituation: Infants always orient towards new stimuli. This helps us tell if the infant can determine differences between two images (do they look to the new one?)
Animal Experiments: sometimes we use animals to try to assess nature vs nurture in the development of vision. Findings have suggested that experience is vital during a sensitive period for vision.
Visual Cliff
Developed in 1960s by Gibson and Walk. Helps us see if an infant can see depth. This is the illusion where one area of a table looks like a cliff (covered in clean glass), and generally it’s used to see if the baby will go over it or be scared bc of the cliff.
Objective Dimensions of Sound
Frequency: the number of cycles per second (measured in Hz). The shorter the wavelength, the higher the frequency.
Intensity: the amplitude/height of the waves (measured in decibels). The more decibels, the louder something is. (140+ is painful).
Three Subjective Dimensions of Sound
Loudness: the subjective experience of the intensity of a sound
Pitch: The subjective experience of the frequency of the sound. (low v high tones).
Timbre: The quality of the sound. (complexity of the sound wave).
Structure/Function of Ear
The outer ear, the fleshy visible part of ear, sound first reaches this area called the pinna which channels sounds into the canal. This channels waves to the eardrum (aka the tympanic membrane). This vibrates w new sounds. The middle ear has the ossicles (malleus, incus, and stapes/hammer, anvil, stirrup) which transmit the vibrations of the eardrum to the inner ear. Then goes through the oval window to reach the inner ear. The inner ear has the cochlea (with cochlear fluid) and the basilar membrane. The organ of corti rests on the membrane, which has thousands of hair cells, which are the receptors for hearing. The bends of the hair cells become electrical charges (no one knows how) which is then transmitted along the nerve fiber to the auditory nerve and to the brain. The auditory nerve projects to the superior olivary complex, the inferior colliculus, the medial geniculate nucleus (in the thalamus) and finally the temporal cortex.
Helmholtz’s Place Resonance Theory
Theory that each different pitch causes different parts of the basilar membrane to vibrate, in turn causing different hair cells to bend and us to perceive sounds of different pitches. Operative for tones higher than 4,000Hz in addition to normal range.
Frequency Theory
Alternate to Place-Resonance Theory. Suggests that the basilar membrane vibrates as a whole, and that the rate of vibration translates to the frequency of the stimulus. This is then translated to the number of neural impulses, which then determines our perception of the pitch. However, this cannot be applied to tones about 1000 Hz (which led to the volley principle, which suggests that high rates of neural firing can be maintained if the fibers work together). Operative for tones up to 500Hz in addition to normal range.
Bekesy’s Traveling Wave Theory
1960s, Bekesy found that movement of the basilar membrane is maximal at different places for different frequencies (even though the whole membrane vibrates for every stimulus).High frequencies vibrate cloest to the oval window, and low frequencies vibrate closest to the apex (tip of the cochlea). Also found that very low frequencies are maximally vibrating in a very large area.
Taste and Smell basics
Chemical senses. Require the receptors to have actual contact with the molecules of the stimulus.
Taste: taste center is in thalamus, and receptors are taste buds on the tongue called papillae.
Smell: Olfactory bulb is center in brain, and receptors are olfactory epithelium in the upper nasal passage.
Touch Transduction
Receptors of touch transduce the information (pressure, pain, warmth, cold) and then information travels to the somatosensory cortex in the parietal lobe.
Types of Tactile Receptors
Pacinian Corpuscles: Deep pressure
Meissner Corpuscles: Touch
Merkel Discs/Ruffini Endings: Warmth
Free nerve endings for everything else.
Two Point Thresholds
AKA Two Point Theory. refers to the minimum distance necessary between two points of stimulation on the skin for us to feel them as distinct stimuli. The size of the threshold depends on the density of nerves in that body area.
Physiological Zero
The way we judge temperature on the skin, physiological zero is the temperature of our skin at any given time. Cold/Hot feelings are all in reference to our physiological zero.
Gate Theory of Pain
Associated with Melzack and Wall. Proposes there is a gating mechanism that turns signals on or off, thus affecting if we perceive pain. The “gate” is in the spinal cord and can block sensory input before the brain receives the pain signals
Proprioception
The general term for our sense of bodily position and includes aspects of both vestibular and kinesthetic senses.
Vestibular Sense
The sense of balance and our body position in relation to gravity. Balance receptors are the semicircular canals in the inner ear.
Kinesthetic Sense
Our awareness of body movement and position in relationship to muscles, tendons, and joint positions (since receptors are near/at these areas.).
Donald Broadbent
Known for proposing that selective attention acts as a filter between sensory stimuli and our processing systems. He hypothesized it was an all or nothing process, so that if we attend to a stimuli we process it, but if we aren’t attending we don’t.
Later empirically proven wrong.
Cocktail Party Phenomenon
Example of how we attend to what we are interested in while not fully ignoring the background noise. For example at a cocktail party you can be fully attending to a conversation, and so the rest of the noise is dampened. But if across the room someone says your name you immediately attend to that. This shows that even though we were fully attending to our conversation, we were still processing the background noise (since you heard your name). Therefore, selective attention cannot be an all or nothing filter.
Dichotic Listening Technique
Used to study selective attention in the lab. This is when two ears are simultaneously presented with different messages. Participants can usually attend to one ear and dampen the other.
Yerkes-Dodson Law
Maintaining attention depends partially on arousal. Law states that performance is worst at extremely low or high levels of arousal, and that optimal performance occurs at an intermediate level of arousal.
