AP Psych - Sensation and Perception

Sensation

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

Perception

The process of organizing and interpreting sensory information

Bottom-up processing

Analysis that begins with the sensory receptors and works up to the brains integration of sensory information

Top-down processing

Information processing guided by higher level mental processes, as when we construct perceptions drawing on our experience and expectations

Psychophysics

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

absolute threshold

The minimum stimulation needed to detect a particular stimulus 50% of the time

Subliminal

Below one’s absolute threshold for conscious awareness

Priming

The activation, often unconsciously, of certain associations, thus predisposing one’s perceptions, memory or response

Difference threshold

The minimum difference between two stimuli required for detection 50% of the time (experienced as just noticeable difference)

Webster’s law

The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage

Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation

Wavelength

The distance from the peak of one light or sound wave to the peak of the next

Hue

The dimension of color that is determined by the wavelength vary from the short blips of cosmic rays to the long pulses of radio transmission (amplitude determines intensity, frequency depends on wavelength)

Intensity

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

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

Accomodation

The process by which the eye’s lense changes shape to focus near on far objects on the retina

Rods

Retinal receptors that detect black, white, and gray, neccesary for peripheral and twilight vision, when cones don’t respond

Cones

Retinal receptors cells concentrated near the center of the retina and that function in the daylight or in well-lit conditions. Detect fine detail and give rise to color sensations

Optic nerve

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

Blind spot

The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there

Fovea

The central focal point in the retina, around which the eye’s cones cluster

Feature detectors

Nerve cells in the brain that respond to specific features of a stimuli (shape, angle, movement)

Paralell processing

The processing of many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions

Young-Hemholtz Trichromatic theory

The theory that the retina contains three different color-receptors - most sensitive to red, green and blue which when stimulated in combination can produce the perception of any color

Opponent-process theory

The theory that opposing retinal processes (red/green, yellow/blue, white/black) enable color vision

Absolute threshold - hearing

A watch ticking 20 ft away

Absolute threshold - smell

Drop of perfume in a 6 room house

Absolute threshold - taste

Teaspoon of sugar in a gallon of water

Absolute threshold - touch

A wing of a fly on your cheek dropped 1 cm

Audition

The sense of act of hearing

Frequency

The number of complete wavelengths that pass a point in a given time

Pitch

A tone’s experienced highness or lowness; depends on frequency. Shorter wavelength = high pitch and small amplitude = softer sound

Middle ear

The chamber between the eardrum and cochlea containing three bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochleas’s oval window

Cochlea

A coiled, bony, fluid filled tube in the inner ear through which sound waves trigger nerve impulses

Inner ear

The innermost part of the ear containing cochlea, semicircular canals and vestibular sacs

Vestibular sense

The sense of a body movement and position, including sense of balance

Kinesthesis

The system for sensing the position and movement of an individual body parts

Gate-control theory

The theory that the spinal cord contains a neurological “gate” that blocks pain signals travelling up small nerve fibers and is closed by activity in large fibers or by info coming from the brain

Taste sensations

sweet, sour, salty, bitter, umami

Sensory interaction

the principle that one sense may influence another (like when smell influences taste)

Just noticeable difference for light

8%

Just noticeable difference for sound

0.3%

Just noticeable difference for weight

2%

Just noticeable difference for taste

20%

Subliminal stimulia

The stimuli is there, but doesn’t reach the 50% threshold

Gestalt

An organized whole

Figure-ground

The organization of the visual field into objects that stand our from their surrounding (ground)

Grouping

The perceptual tendency to organize stimuli into coherent groups by proximity, similarity, continuity, connectedness, closure

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

Visual cliff

A laboratory device for testing depth perception in infants and young animals

Binocular cues

Depth cues, such as retinal disparity, that depend on the use of two eyes

Retinal disparity

A binocular cue for perceiving depth: by comparing images from the retinas in the two eyes, the brain computes distance the greater the disparity between the two images, the closer the object

Monocular cues

Depth cues, such as interposition and linear perspective

Horizontal-verticle illusion

We perceive verticle dimensions as longer than horizontal

Relative height

We perceive objects high in our field of vision as far away

relative size

If we assume 2 objects are similar in size, we usually perceive the one that cases the smaller retinal image as farther away

Interposition

If something blocks our view of something we perceive it as closer

Linear perspective

The more paralell lines converge, the farther away they seem

Light and shadow

Dimmer objects seem more far away, shading can also create a sense of depth

Relative motion

Objects beyond a fixation point appear to move backwards

Perceptual consistency

Perceiving objects as unchangning even as illumination and retinal images change (shape constancy)

Size-distance relationship

Perceived distance and perceived size

Lightness constancy

We perceive an object as having constant lightness even while illumination varies

Relative luminace

Amount of light an object reflects to its surroundings

Color constancy

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

Perceptual adaptation

In vision, the ability to adjust to an artificially displaced or even inverted visual field

Perceptual set

A mental predisposition to perceive one thing and not another

Extrasensory perception

The controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance and precognition

Parapsychology

The study of paranormal phenomena including ESP and kinesis

Proprioception

Vision, vestibular sense, kinesthetic sense

Texture gradients

Monocular cue, things closer look coarser and things farther away look finer