Chapter 6: Sensation and Perception

Sensation

Sensation

Sensory receptors and nervous system detecting physical energy from the environment and encoding it as neural signals

Bottom-Up Processing (Feature Analysis)

Analysis that begins with basic senses, then works up to the brain’s interpretation (detecting lines, angles, colors)

Perception

Selecting, organizing, and interpreting our sensations as meaningful objects and events

Top-Down Processing

Perceiving things based on personal prior knowledge, experiences, and expectations (considering background information)

Perceptual Interpretation/Adaptation

Ability to adjust to an artificially displaced or inverted visual field (prism glasses cause disorientation, then the brain adjusts after 1–2 days)

Psychophysics

The study of how physical energy relates to our psychological experience

Transduction

Conversion of one form of energy into another; stimulus energy goes from the senses to the thalamus, then to the brain as neural impulses

Absolute Threshold

The minimum stimulation needed to detect a particular stimulus, 50% of the time (increases with cataracts)

Difference Threshold (Just Notable Difference)

The minimum difference a person can detect between any two stimuli, 50% of the time

Weber’s Law

Difference thresholds differ by a constant percentage rather than amount; harder to detect change in larger stimulus (weight must differ by 2%, light intensity by 8%)

Signal Detection Theory

Predicts when we will detect weak stimuli amid background noise; certain senses can be affected more by motivation, experience, expectations, or physical state

Subliminal Messages

Unconsciously sensing stimuli below our absolute threshold, which can prime later behavior to a very small degree (must already have the intention to do so)

Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation to help us focus on changes in our environment

Wavelengths

The distance from the peak of one light or sound wave to the peak of the next; gives us its hue/color (longer = red, shorter = blue)

Pupil

Adjustable opening in the center of the eye, which lets light in

Iris

A ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening (brighter = contracts, darker = enlarges)

Cornea

Protects the eye from debris and bends light to provide focus

Lens

Transparent structure behind pupil that changes shape through accommodation to bend light and focus images on the retina

Retina

The light-sensitive inner surface of the eye, containing receptor rods, cones, and layers of neurons that begin the processing of visual information (shows images upside down)

Optic Nerve

Nerve that carries neural impulses from the eye to the brain

Blind Spot

Point at which the optic nerve leaves the eye, creating a lack of perception because there are no receptor cells located there

Fovea

Central point in the retina, around which the eye’s cones cluster (too far in front = nearsightedness, too far behind = farsightedness)

Vision Correction

Glasses, contact lenses, or LASIK surgery reshape the cornea to correct the problem

Acuity

The sharpness of vision, which can be affected by distortion in the eye's shape

Nearsightedness

Condition in which nearby objects are seen more clearly than distant objects because the image of distant objects is focused in front of retina

Farsightedness

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

Rods

120 million retinal receptors along the peripheral of the retina, which detects black, white, and gray in twilight or low light vision

Cones

6 million retinal receptor cells near the center of the retina, which detects fine detail and color vision in daylight or well-lit conditions

Feature Detectors

Nerve cells in the visual cortex that respond to specific features shape, angle, movement)

Amplitude

The amount of energy/height in a light or sound wave; gives us its intensity/brightness/loudness (greater = bright, smaller = dull)

Accommodation

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

Parallel Processing

Processing of several aspects of an object simultaneously (color, motion, form, depth)

Young-Helmholtz’s Trichromatic Theory of Color Vision

The theory that the retina contains three types of cones most sensitive to red, blue, and green; which can produce the perception of any color when stimulated in combination, but does not explain afterimages

Color-Deficient Vision

Red-green blindness causes trouble perceiving the number within the design, lacking functioning red or green sensitive cones, or sometimes both (monochromatic or dichromatic instead of trichromatic)

Opponent-Process Theory of Color Vision (Afterimage Effect)

The theory that sensory receptors come in pairs and the opposing retinal processes (red-green, yellow-blue, white-black) enables color vision; and if one color is stimulated, the other is inhibited

Sclera

Protective white outer layer of the eye that maintains the shape of the eyeball and shields the inner structures

Bipolar Cells

Interneurons in the retina that transmit signals from rods and cones to ganglion cells

Ganglion Cells

Interneurons in the retina that transmit visual information from bipolar cells to the optic nerve

Visual Capture

Vision dominates other senses, influencing our perception of the world and our reliance on visual information

Transduction in the Eye

Light enters the eye through the cornea, passes through the pupil and iris, and gets focused by the lens onto the retina, which contains rods and cones; bipolar and ganglion cells process the visual information, and the optic nerve transmits signals to the thalamus, which relays them to the visual cortex in the brain, enabling the perception of sight

Decibels

The measuring unit for sound energy; prolonged exposure above 85 decibels produces hearing loss

Conduction Deafness

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea (such as a damaged eardrum); can replace the bones or get a hearing aid

Sensorineural (Nerve) Deafness

Hearing loss caused by damage to the cochlea’s hair cells or to the auditory nerves, which can be caused by loud noises; no way to replace cells, but cochlear implant is possible

Selective Attention

Focus of conscious awareness on a particular stimulus; shifting our attention from one thing to another

Cocktail Party Effect

A form of selective attention, the ability to attend to one voice among many

Transduction in the Ear

Sound waves enter the outer ear, travel through the auditory canal, and make the eardrum vibrate, setting the hammer, anvil, and stirrup bones in motion; vibrations travel to the oval window, creating fluid movement in the cochlea, stimulating the basilar membrane (mucus) and hair cells, and sending impulses through the auditory nerve to the thalamus and auditory cortex for sound perception; the semicircular canals and Eustachian tube contribute to balance and pressure regulation

Hair Cells

Sensory receptors in the cochlea that convert sound wave vibrations into neural signals for the brain, allowing for auditory perception

Outer Ear

Consists of the auditory canal and eardrum; collects and funnels sound waves toward the eardrum

Auditory Canal

A tube-like structure in the outer ear that channels sound waves from the external environment to the eardrum

Eardrum

A thin, membrane-like structure in the outer ear that vibrates in response to sound waves, transmitting them to the middle ear

Middle Ear

The chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window and transmits them to the inner ear

Hammer, Anvil, Stirrup

Three small bones in the middle ear responsible for transmitting sound vibrations from the eardrum to the inner ear

Oval Window

A membrane-covered opening in the middle ear that transmits vibrations from the middle ear to the fluid-filled cochlea in the inner ear

Eustachian Tube

Part of the middle ear; helps equalize air pressure between the ear and the environment, contributing to optimal hearing function

Inner Ear

The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs; converts sound vibrations into neural signals for hearing and maintaining balance

Cochlea

A spiral-shaped, fluid-filled structure in the inner ear responsible for converting sound vibrations into neural signals

Basilar Membrane

A fluid located in the inner ear within the cochlea; detects different frequencies of sound vibrations

Semicircular Canals

Located in the inner ear; maintain balance and spatial orientation

Vestibular Sacs

Located in the inner ear; detects changes in head position and movement, contributing to sense of balance and spatial orientation

Place Theory

The pitch we hear depends on the place where the cochlea’s membrane is stimulated; some hairs vibrate when they hear high or low pitches (best determines highest pitches)

Frequency Theory

The pitch we hear depends on the rate of nerve impulses traveling up the auditory nerve; the hairs vibrate but at different speeds (best determines lowest pitches)

Sensory Interaction

The principle that one sense may influence another; smell, taste, and touch work together

Taste (Gestation)

Experience of taste depends on internal state (taste better when hungry), past experiences (familiar foods), genes (different sensitivities to certain tastes), effects of adaptation (clashing taste sensations), smell and texture (touch)

Smell (Olfaction)

Sense of smell (linked to taste and emotion), the only sensation that does not go to the thalamus first; fragrance molecules reach receptors at the top of the nose, then the brain’s olfactory bulb, and to the limbic system (memory and emotion)

Touch

Receptors located in our skin, essential to development (skin contact); four skin senses include pressure (only sense with receptors), warmth, pain, and cold

Gate Control Theory of Pain

The theory that the spinal cord contains a neurological “gate” that can allow or block pain signals from passing through (small fibers = open, large fibers = close)

Kinesthetic Sense

The system for sensing the position and movement of individual body parts; ability to be coordinated (vision plays a role)

Vestibular Sense

Tells us where our body is oriented in space, our sense of balance; located in our semicircular canals in our ears and guided by cerebellum

Inattentional Blindness

Failing to see visible objects when our attention is directed elsewhere; we see very little when we are not paying attention

Change Blindness

Failing to notice a visual change when our attention is directed elsewhere

Gestalt Psychology

Developed in Germany early in the 20th century, focuses on how we group objects together and not as isolated elements

Gestalt Principle of Closure

The tendency to complete figures that are incomplete or to integrate pieces of information into meaningful wholes

Gestalt’s Figure Ground Relationship

The tendency to perceive objects, or figures, as existing on a background; cannot see both at once

Gestalt Principle of Proximity

The tendency to perceive objects that are close to each other as part of the same grouping

Gestalt Principle of Similarity

The tendency to group things together that appear similar to each other

Gestalt Principle of Continuity

The tendency to see continuous and smooth flowing lines rather than broken or jagged ones

Gestalt Principle of Connectedness

The tendency to group elements when they are connected to each other (hand holding and relationship assumptions)

Gestalt Principle of Grouping

The perceptual tendency to organize stimuli into coherent groups

Depth Perception (Visual Cliff Experiment)

The ability to see objects in three dimensions, which allows us to judge distance; can see if old enough to crawl

Monocular Cues

Depth cues used by either eye alone to judge depth perception (linear perspective, interposition, relative size, relative height, relative motion, light, shadow)

Linear Perspective

A monocular cue that involves the convergence of parallel lines, creating distance in two-dimensional images

Interposition

A monocular cue that occurs when one object partially obscures another, suggesting that it is farther away

Relative Size

A monocular cue that refers to the visual perception that objects appearing larger are closer, while smaller ones are perceived as more distant

Relative Height

A monocular cue that involves perceiving objects higher in the visual field as more distant

Light and Shadow

Monocular cues that interpret the way light falls on objects, allowing us to distinguish their shapes and positions in the environment

Binocular Cues

Depth cues used by both eyes to judge depth perception (retinal disparity, convergence)

Retinal Disparity

A binocular cue where the differences in images between our eyes becomes greater as an object comes closer to us

Convergence

A binocular cue where our eyes have to come together to keep focused on the object as an object comes closer to us

Phi Phenomenon

Illusion of movement created when two or more adjacent lights blinks on and off in quick succession

Perceptual Constancy

Perceiving objects as unchanging even as illumination and retinal image change (color, shape, size, lightness)

Perceptual Set

A mental predisposition to perceive one thing and not another; tend to notice only certain aspects of an object or situation while ignoring other details

Color Constancy

The ability to perceive the consistent color of an object under varying lighting conditions, allowing individuals to recognize objects with stable colors despite changes in illumination

Shape Constancy

The tendency to perceive an object as maintaining its shape despite changes in the viewing angle, providing a stable representation of the object's form

Size Constancy

The ability to perceive an object as having a constant size, regardless of variations in its distance from the observer, ensuring that the perceived size remains consistent

Lightness Constancy

The ability to perceive an object's lightness as relatively constant, regardless of alterations in illumination conditions, enabling a stable perception of the object's visual characteristics

Schemas

What you see in the center is influenced by perceptual set

Face Schemas

Our face recognition capabilities are mostly attuned to the eyes and mouth

Human Factors Psychology

A branch of psychology that explores how people and machines interact; how machine and physical environments can be adapted to human behaviors

Parapsychology

The study of paranormal phenomena, including ESP and psychokinesis

Extrasensory Perception (ESP)

The controversial claim that perception can occur apart from sensory input (telepathy, clairvoyance, precognition, psychokinesis)