AP Psych - Sensation and Perception

Sensation

the activation of receptors in the various sense organs

Absolute Threshold

the smallest amount of energy needed for a person to consciously detect a stimulus 50 percent of the time it is present

Retina

final stop for light in the eye contains three layers: ganglion cells, bipolar cells, photoreceptors that respond to various light waves

Cones

visual sensory receptors found at the back of the retina; responsible for color vision and sharpness of vision

Difference threshold

the smallest difference between 2 stimuli that are detectable 50 percent of the time

Perception

the method by which the sensations experienced at any given moment are interpreted and organized in some meaningful fashion

Rods

visual sensory receptors found at the back of the retina; responsible for noncolor sensitivity to low levels of light

Opponent Process Theory (color)

theory of color vision that proposes four primary colors with cones arranged in pairs: red and green, blue, and yellow

Fovea

Very center of the retina where there are no rods, but there is a large concentration of cones.

Trichromatic theory

theory of color vision that proposes three types of cones: red, blue, and green

Cochlea

the snail-shaped structure of the inner ear that is filled with fluid

Perceptual constancy

refers to the tendency to perceive an object you are familiar with as having a constant shape, size, and brightness despite the stimuli changes that occur.

Monocular cues

(pictorial depth cues): cues for perceiving depth based on one eye only

Pheromones

Chemical signals released by organisms to communicate with other members of their species

Transduction

turning outside stimuli into neural activity

Weber's law

Whatever the difference between stimuli may be, it is always a constant.

Binocular Cues

cues for perceiving depth based on both eyes

Place theory

theory of pitch that states that different pitches are experienced by the stimulation of hair cells in different locations on the organ of Corti

Retinal disparity

differences between the images received by the left eye and the right eye as a result of viewing the world from slightly different angles; binocular depth cue, since the greater the difference between the two images, the nearer the object

Taste buds

taste receptor cells in the mouth; responsible for the sense of taste

Pitch

psychological experience of sound that corresponds to the frequency of the sound waves; higher frequencies are perceived as higher

Bottom-up processing

the analysis of the smaller features to build up to a complete perception

Feature detector

Cells that respond to specific features of a stimulus.

Gate control theory

pain signals must pass through a "gate" located in the spinal cord

Psychophysics

quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce

Sensory adaptation

the tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging

Signal detection theory

Your ability or likelihood to detect some stimulus is affected by the intensity of the stimulus (e.g., how loud a noise is) and your physical and psychological state (e.g., how alert you are).

Top-down processing

the use of preexisting knowledge to organize individual features into a unified whole

Accommodation (perceptual)

what occurs when new information or experiences cause you to modify your existing schemas. Rather than make the new information fit into an existing schema, you change the schema in order to accommodate the new information.

Frequency theory

theory of pitch that states that pitch is related to the speed of vibrations in the basilar membrane

Habituation

the tendency of the brain to stop attending to constant, unchanging information

Lens

another clear structure behind the iris, suspended by muscles; finishes the focusing process begun by the cornea

Optic nerve

Sends visual information to the brain.

Pupil

hole through which light from the visual image enters the interior of the eye

Vestibular sense

the sensations of movement, balance, and body position

Blindspot

the area in the retina where the axons of the three layers of retinal cells exit the eye to form the optic nerve; insensitive to light

Dark Adaptation

the recovery of the eye's sensitivity to visual stimuli in darkness after exposure to bright lights; night blindness

Iris

round muscle (the colored part of the eye) in which the pupil is located; can change the size of the pupil, letting more or less light into the eye; helps focus the image

Olfaction

Sense of smell

Convergence

the rotation of the two eyes in their sockets to focus on a single object, resulting in greater convergence for closer objects and lesser convergence if objects are distant

Hue

is determined by the length of the wave; long wavelengths are found at the red end of the visible spectrum (the portion of the whole spectrum of light that is visible to the human eye); shorter wavelengths are found at the blue end

Shape constancy

the tendency to interpret the shape of an object as being constant, even when its shape changes on the retina

Size constancy

the tendency to interpret an object as always being the same actual size, regardless of its distance

Cornea

Clear membrane that covers the surface of the eye. Bends light waves so the image can be focused on the retina

Subliminal perception

the process by which subliminal stimuli act upon the unconscious mind, influencing behavior

Gustav Fechner

Expanded on Weber's work by studying absolute threshold

David Hubel

Demonstrated that neurons in the occipital lobe's visual cortex receive information from individual ganglion cells in the retina (feature detector cells)

Ernst Weber

Created Weber's law; worked with just noticeable difference/difference threshold.

Torsten Weisel

studied visual information processing and development in the US during the twentieth century. He performed multiple experiments on cats in which he sewed one of their eyes shut and monitored the response of the cat's visual system after opening the sutured eye.

Gibson

believed that perception is direct and meaningful