Psychology Unit 3- Sensation and Perception

Gate-control theory

- the theory that the spinal cord contains a neurlogical "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming to the brain - explains how we experience pain-->some pain messages have a higher priority than others, when a high-priority message is sent, the gates swing open for it and shut down for low-priority messages, which will not be felt

Lens

- the transparent stucture behind the pupil that changes shape to help focus images on the retina. - focuses light that enters the pupil - curved and flexible in order to focus the ligth - as the light passes through the lens, the image is flipped upside down and inverted- the focused inverted image projects on the retina

Sound waves

- vibrations in the air. they travel through the air and are collected by our ears. - sound waves have amplitude and frquency.

Brightness constancy

- we perceive objects as being a constant color even as the light reflecting off the object changes

Fovea

- the central focus point in the retina, around which the eye's cones cluster -When light is focused onto your fovea, you see it in color. - foveal vision, focusing light on the fovea, results in the sharpest and clearest visual perception - your peripheral vision, especially at the extremes, relies on rods and is mostly in black and white

Middle ear

- the chamber between the eardrum and cochlea containing three tiny bones (anvil, hammer, stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

Extrasensory Perception (ESP)

- the controversial claim that perception can occur apart from sensory input. Said to include telpathy, clairvoyance, and precognition

Hue

- the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green and so forth

Wavelength

- the distance from the peak of one light or sound wave to the peak of the next. Shows hue in vision and pitch in sound.

Retina

- the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information - like a screen on the back of your eye - as the light passes through the lens, the image is flipped upside down and projected on the retina. - special neurons in the retina (rods and cones) are activated by light and send impulses along the optic nerve to the occipital lobe of the brain

Difference Threshold (just-noticeable difference)

- the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticable difference - computed by weber's law

Absolute Threshold

- the minimum stimulation needed to detect a particular stimulus 50 percent of the time. - for example, the absolute threshold for vision is the smallest amount of light we can detect, which is estimated to be a single candle flame about 30 miles away on a perfectly dark night

Optic Nerve

- the nerve that carries neural impulses from the eye to the brain (occipital lobe) - it is divided into two parts. Impulses from the left side of each retina (right visual field) go to the left hemisphere of the brain, and those from the right side of each retina (left visual field) go to the right side of the brain

Frequency

- the number of complete wavelengths that pass a point in a given time (for example, per second)- determines pitch, measured in megahertz

Figure-Ground

- the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground)

Grouping

- the perceptual tendency to organize stimul into coherent groups

Blind Spot

- the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there. - we do not really notice it because the movement of our eyes accommodates for the blind spot

Sensory interaction

- the principle that one sense may influence another, as when the smell of food influences its taste

Weber's Law

- the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount) - named after psychophysicist Ernst Weber - change needed is proportional to the original intensity of the stimulus. The more intense the stimulus is, the more it will need to change before we notice a different

Sensation

- the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. - process occuring when one of our senses is activated by something in our environment. - occurs before the process of perception

Parallell Processing

- the processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrasts with the step-to-step processing of most computers and conscious problem solving

Vestibular sense

- the sense of body movement and position, including the sense of balance - semicircular canals in the inner ear give the brain feedback about body orientation (fluid moves in the canals when position of head changes, causing sensors in the canals to move which sends impulses to the brain)

Chemical Senses

- the senses of taste and smell - these senses work by gathering chemicals

Parapsychology

- the study of paranormal phenomena, including ESP and psychokinesis

Visual Capture

- the tendency of vision to dominate the other senses

Opponent-Process Theory

- the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others ares stimulated by red and inhibited by green - If one sensor is stimulated, its pair is inhibited from firing. - this theory explains afterimages and colorblindness - most researchers think that color vision is explained by a combination of both theories

Young-Helmholtz trichromatic (three color) theory

- the theory that the retina contains three different color receptors- one most sensitive to red, one to green, one to blue- which when stimulated in combination can produce the perception of any color - these cones are activated in different combinations to produce all the colors of the visible spectrum - theory has some research support and makes sense intuitively, it cannot explain afterimages and colorblindness - most researchers think that color vision is explained by a combination of both theories

Visible light

-color is perceived due to a combination of different factors: 1. light intensity- how much energy the light contains determines how bright the object appears. 2. light wavelength- the length of the light waves determines the particular hue we see. We see different wavelengths within the visible light spectrum as different colors.

Transduction

-conversion of one form of energy into another -translation of incoming stimuli into neural signals - neural impulses from the senses travel firs to the thalamus and then on to different cortices of the brain (except smell)

Kinesthetic Sense (kinesthesis)

-system for sensing the position and movement of individual body parts - receptors in our muscles and joints send information to our brain about our limbs - this information, combined with visual feedback, lets us keep track of our body.

Acuity

-the sharpness of vision.

Nearsightedness

A condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina

Phi Phenomenon

An illusion of movement created when two more more adjacent lights blink on and off in succession

Binocular cues

depth cues, such as retinal disparity and convergence, that depend on the use of two eyes

Monocular cues

distance cues, such as linear perspective and overlap, available to either eye alone

Perceptual Adaptation

in vision, the ability to adjust to an artifically displaced or even inverted visual field

Accommodation

The process by which the eye's lens changes shape to focus near or far objects on the retina

Light and Shadow

We assume that light comes from the top so objects with light on top appear closer to us.

Texture gradient

We can see texture on a 2-D surface by changing density and sizes of shapes

Relative motion

We perceive motion outside of a window when we are moving, even though those objects are stable.

Stereophonic Hearing

When a noise occurs on your right, the sound wave comes to both ears, but is reaches your right ear a fraction of a second before it reaches your left. It is also slightly louder in the right ear. These differences tell you from which direction the sound is coming (This is why dogs cock their heads)

Retinal disparity

a binocular cue for perceiving depth: by comparing images from the two eyeballs, the brain computes distance- the greater the disparity (difference) between the two images, the closer the object

Convergence

a binocular cue for perceiving depth; the extent to which the eyes converge inward whe looking at an object

Cochlear Implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

Iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.

Pupil

adjustable opening in the center of the eye through which light enters. - similar to the shutter of a camera. - muscles that control the pupil (called the iris) open it (dilate) to let more light in and also make it smaller to let less light in.

Stimulus

any aspect or change in the environment to which an organism responds

Color Constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

Cornea

protective covering on the front of the eye that helps focus the light

Selective Attention

the focusing of conscious awareness on a particular stimulus. At any moment we focus our awareness on only a limited aspect of all that we experience.

Audition

the sense of hearing

Psychophysics

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them

Cocktail-Party Phenomenon

- If you are talking with a friend and someone across the room says your name, your attention will probably involuntarily switch across the room - ex of selective attention

Hearing

- Occurs in several steps 1. sound waves, vibrations in the air, travel through the air, and are then collected by our ears 2. sound waves have amplitude and frequency 3. amplitude is the height of the wave and determines the loudness of the sound, which is measured in decibels 4. frequency, measured in megahertz, referes to the length of the eaves and determines pitch. 5. vibrations enter the ear and vibrate the eardrum, which connects with three bones in the middle ear: the hammer (malleus), anvil (incus), and the stirrup (stapes) 6. the vibration is trasnferred to the oval window, a membrane very similar to the eardrum 7. the oval window membrane is attached to the cochlea, where the process of transduction occurs and neural messages are sent to the auditory cortex in the temporal lobe.

Sensory Habituation

- Our perception of sensations is partially determined by how focused we are on them. - Ex. No longer hearing traffic from the nearby freeway after having lived in a place for years.

Depth cues

- Researchs divide the cues that we use to perceive depth into two categories: 1. monocular cues 2. Binocular Cues

Energy senses

- Senses of vision, hearing and touch - gather energy in the form of light, sound waves and pressure respectively.

Optic Nerve

- The nerve that carries neural impulses from the eye to the brain

Perception

- The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. - occurs after the process of sensation

Bipolar Cells and Ganglion Cells

- These cells make up different layers in the retina. - In the retina, light activates rod and cone cells - Rods and cones send signals to the next layer of cells in the retina: bipolar cells - Bipolar cells send signals to the next layer of cells in the retina: ganglion cells - ganglion cells send signals to the brain through the optic nerve

Human Factors Psychology

- a branch of psychology that explores how people and machines interact and how machines and physical environments can be adapted to human behaviors

Cochlea

- a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses - the process of transduction (where sound waves are changed into neural impulses) occurs in cochlea -as sound waves move the fluid, hair cells move - neural messages are sent to the auditory cortex of the temporal lobe

Farsightedness

- a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina

Perceptual set

- a mental predisposition to perceive one thing and not another - our experience creates schemata, mental representations of how we expect the world to be. Our schemata influence how we perceive the world - schemata can create a perceptual set

Signal Detection Theory

- a theory predicting how and when we detect the presence of a faint stimulus ("signal") amid background stimulation ("noise"). Assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation and level of fatigue - tries to explain and predict the different perceptual mistakes we make ( such as not seeing a stop sign)

Pitch

- a tone's highness or lowness; depends on frequency

Gestalt

- an organized whole. Gestalt psychologists emphasize our tendency to integrate pieces of information into meaningful wholes - process is believed to be innate and inevitable - describe principles that govern how we perceive groups of objects (proximity, similarity, continuity, closure)

Bottom-Up Processing

- analysis that begins with the sense receptors and works up to the brain's integration of sensory information - We use the features of the object itself to build a complete percetion

Sensory Adaptation

- decreasing responsiveness to stimuli due to constant stimulation. - Ex. we eventually stop perceiving a persistent scent in the room.

Depth perception

- the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

Intensity

- the amount of energy in a light or sound wave, which we perceive as brightness or loudness as determined by the wave's amplitude.

Vision

- dominant sense of human beings. sighted people use vision to gather information about their environment more than any other sense - process of vision involves several steps: 1. light is reflected off objects 2. reflected light coming from the object enters eyes through the cornea and pupil, is focused by the lens, and is projected on the retina where specialized neurons are activated by the different wavelengths of light. 3. transduction occurs when light activates the special neurons in the retina and sends impulses along the optic nerve to the occipital lobe of the brain. 4. impulses from the left side of the each retina (right visual field) go the the left hemisphere of the brain, and those from the right side of each retina (left visual field) go to the right side of the brain. 5. visual cortex receives the impulses from the retina, which activate feature detectors for vertical lines, curves, motion, among others. What we perceive visually is a combination of these featuers.

Sensoineural hearing loss (Nerve Deafness)

- hearing caused by damage to the cochlea's receptor cells or to the auditory nerves - occurs when the hair cells in the cochlea have been damaged usually by loud noise - difficult to treat because no method yet found that will encourage the hair cells to regenerate

Conduction Hearing Loss

- hearing lose caused by damage to the mechanical system that conducts sound waves to the cochlea

Amplitude

- height of the wave and determines the loudness of the sound, measured in decibels

Place Theory

- in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated -explains that hair cells in the cochlea respond to different frequencies of sound based on where they are located in cochlea - accurately describes how hair cells sens the upper range of pitches but not the lower tones

Frequency Theory

- in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch - lower tones are sensed by the rate at which cells fire - we sens pitch because the hair cells fire at different rates (frequencies) in the cochlea

Color blindness

- individuals with dichromatic color blindness cannot see either red/green shades or blue/yellow shades - those who have monochromatic color blindness see only shades of gray

Top-Down Processing

- information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations - we perceive by filling in gaps in what we sense ( by using background knowledge)

Occipital Lobe

- location of the visual cortex - part of the brain that processes vision sensations - receives impulses via the optic nerve

Smell (olfaction)

- molecules of substances rise into the air and are drawn into our nose. - the molecules settle in a mucous membrane at the top of each nostril and are absorbed by receptor cells located there. - as many as 100 different types of smell receptors may exist. These receptor cells are linked to the olfactory bulb, which gathers the messages from the olfactory receptor cells and sends this information to the brain - nerve fibers from the olfactory blub connect to the brain at the amygdala and then to the hippocampus, which make up the limbic systen, which is reponsible for emotional impulses and memory. - this direct connection to the limbic system may explain why smell is such a powerful trigger for memories

Feature Detectors

- nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement - visual cortex has feature detectors for vertical lines, curves, and motion, among others. What we perceive visually is a combination of these features

Taste (gustation)

- nerves involved in the chemical senses (taste and smell) respond to chemicals rather than energy - taste buds on the tongue absorb chemicals from the food we eat - taste buds are located on papillae, the bumps you can see on your tongue. Taste buds are located all over the tongue and on some parts of the inside of the cheeks and roof of the mouth - humans sense five different types of tastes: sweet, sour, salty, umami, bitter - people differ in their ability to taste food. the more densely packed the taste buds, the more chemicals are absorbed, and the more intensely the food is tasted - flavor of food is actually a combination of taste and smell

Size constancy

- objects closer to our eyes will produce bigger images on our retinas but we take distance into account in our estimations of size - we keep a constant size in mind for an object and know that is does not grow or shrink in size as it moves closer or farther away

Shap constancy

- objects viewed from different angles will produce different shapes on our retinas, but we know the shape of an object remains constant

Perceptual Constancy

- perceiving objects as unchanging (having consistent lightness, color, shape and size) even as illumination and retinal images change

Cones

- receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.

Rods

- retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond

Touch

- sense of touch is activated when our skin is indented, pierced, or experiences a change in temperature - some nerve endings in the skin respond to pressure; others respond to temperature - brain interprets the amount of indentation (or temperature change) as the intensity of the touch, from a light touch to a hard blow - we sense placement of the touch by the place on our body where the nerve endings fire - nerve endings are more concentrated in different parts of the body. If we want to feel something, we usually use our fingertip, an area of high nerve concentration, rather than the back of our elbow, an area of low nerve concentration - pain is a useful response because it warns us of potential dangers

Subliminal messages

- stimulti below one's absolute threshold for conscious awareness - research does not support claim that subliminal messages affect our behavior in overt ways

Inner ear

- th einnermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.

Amplitude

Height of the wavelength. Shows brightness in vision and loudness in sound.

Linear Perspective

In order to draw lines on a 2-d surface we can not draw them parallel, we have to draw them converging.

Relative height

Objects that are higher in our visual field, we assume are father away. Ex. Mountains, Skyscrapers

Visual Cliff Experiment

Labratory device testing depth perception in infants and young animals. The glass top table makes it appear that there will be a drop and babies do not crawl onto it.

Interposition

Monocular cue. If one object is blocking another object, the object being blocked is farther and the object doing the blocking is closer.

Relative clarity

Monocular cue. If part of your visual field is blurrier, that is farther away from you.

Relative size

Monocular cue. Objects farther away appear smaller.