Psychology chapter 3; Unit 2 Sensation and Perc

Sensation

The process through which we detect physical energy from the environment and code that energy into specific neural signs

Perception

Process in which the brain selects, organizes, and interprets sensory information.

Receptor cell

A cell in a sensory organ stimulated by energy, leading to sensation.

Transduction

A process through which physical energy, such as light or sound, is converted into an electrical (neural) change.

Psychophysics

The study of a relationship between physical characteristic of stimuli and the sensory experiences that accompany them.

Absolute threshold

The smallest amount of energy needed to detect a stimulus (light, sound, pressure, taste, or odor) at least 50% of the time.

Difference threshold

The minimum difference between two stimuli needed to detect the difference at least 50% of the time.

Weber’s Law

Law in psychophysics; the difference between two objects varies proportionally to the initial size of stimulus

Signal detection theory

A theory explaining differences in people’s responses to stimuli based on varying circumstances.

Subliminal perception

When sensation falls below the absolute threshold

Subliminal persuasion

Using subliminal techniques to influence people’s behaviors

Subliminal adaptation

Occurs when your senses are exposed to an unchanging stimulus and eventually stop registering the existence of that stimulus

Wavelengths

The distance between the peak of each wave of energy; measured in nanometers

Hue

Color, which is derived from wavelengths of light that hits the eye.

Brightness

A characteristic of color derived from the amplitude, or height of wavelengths

Saturation

Refers to the richness of color

Cornea

The protective cover over the eye; refracts light and focuses on objects

Pupil

Small hole in the middle of the eye that allows light to enter.

Iris

A colored muscle that dilates (gets bigger) or constricts (gets smaller) the pupil in response to light

Lens

A flexible structure in the eye that changes shape to refract and focus light.

Visual accommodation

A process that involves the lens of the eye changing shape to best refract and focus the light on the retina

Presbyopia

A hardening of the lens of the eye that leads to blurred near vision, typically occurs around the ages of 35 and 60

Retina

Multilayered tissue at the back of the eye responsible for visual transduction, or the conversion of light stimuli into neural communication leading to vision.

Rods

Retinal receptors that respond to varying degrees of light and dark; work best in dimly lit conditions.

Fovea

A depressed spot in the retina that occupies the center of the visual field.

Cons

Visual receptors specializing in the perception of color; found primarily in the fovea

Optic nerve

Nerve that carries the neural messages from the eye to the brain to be processed.

Blind spot

Receptorless area at the back of the eye where the optic nerve exits; images focused on this part of the retina are not seen in the visual field.

Optic chiasm

An area in the brain where a portion of both optic nerves cross over and continue to the visual cortex

Feature detector

Neurons that respond to specific types of features in the visual field.

Parallel processing

The ability of the brain to simultaneously perceive many aspects of an object at one time.

Blindsight

Blindness in part of the visual field due to damage to the primary visual cortex; despite not being able to consciously see, individuals are often aware of the characteristics objects in the blind spot.

Subtractive color mixture

When adding additional colors removes wavelengths of light, eventually resulting in black

Additive color mixture

A process involving the mixing of light, where additional wavelengths are added together and reflected, eventually creating white light.

Trichromatic theory of color vision

A theory that there are three different types of retinal receptors that are each sensitive to varying wavelengths of light, also called young Helmholtz theory of color vision.

Short wavelength cones

Absorb up to 419-nm (blue cones)

Medium wavelength cones

Absorb up to 531-nm (green)

Long wavelength cones

Absorb up to 558-nm (red)

After image

An image that remains in the visual field once the stimulus has been removed

Negative after image

An after image where the colors seen are the opposite of those originally presented

Opponent process theory

Theory of color vision stating there are three special visual receptors that work in pairs and in an opposing manner

Microsaccades

Small, jerky movements of the eye, which allows neurons to reset therefore preventing exhaustion

Soundwave

A change in air pressure caused by molecules of air or fluid colliding and moving apart.

Frequency

The rate of a sound wave measured in cycles per second, or hertz (Hz), determines the pitch of sound.

Timbre

Referring to sound; the purity and complexity of tone.

Sound shadow

The absorption of sound by the head; sound waves hit one ear first, then are dampened by the head, which aids in location of sound.

Eardrum

Part of the outer ear that vibrates in response to sounds in the environment.

Cochlea

A fluid filled structure in the inner ear that receives vibrations from the small bones of the middle ear. (Hammer, anvil, stirrup)

Basilar membrane

Hair cell receptors

Place theory

Frequency theory

Volley principle

Sensorineural hearing loss

Cochlear emplant

Conductive hearing loss

Mixed hearing loss

Amplitude

Olfaction

Taste buds

21 square feet

The amount of skin on body

Gate control theory of pain

Theory suggesting information about pain in conveyed through two different nerve fibers (a thin fiber for pain and a thicker fiber relaying touch, pressure, and vibration) pain can be inhibited by activating large nerve fibers which closes the smaller pain gates.

Proprioceptors

Sensory receptors that provide info about body position and movement

Bottom up processing

Method of perception that involves processing information from the raw data, or environmental stimuli, up to the brain.

Top-down processing

Perception that relies heavily on previous knowledge and experience; also known as knowledge based processing.

Perceptual constancy

The perception of a stimulus remains the same even though some of its characteristics may have changed.

Size constancy

The perception of an objects size doesn’t change, regardless of changes in distance.

Color constancy

Recognizing that the color of an object doesn’t change even though the reflected wavelengths of light change in different environments; for example, knowing a red apple is red regardless of whether or not it is seen during the day or night.

Shape constancy

Objects are perceived as the same shape even though the retinal image may change as a result of different view point.

Perceptual set

The tendency for previous experiences and expectations to influence how situations or objects are perceived.

Illusory contour

A visual illusion where lines or contours are perceived but do not exist.

Proximity

Tendency to perceive objects close to one another as part of the same group

Similarity

Tendency to perceive objects that are the same shape, size, or color as part of a pattern

Closure

Gestalt (form or whole) principle of perception involving the tendency to perceive images as complete objects

Continuity

Gestalt principle of perception involving the tendency to view intersecting lines as part of a continuous pattern rather than a series of separate lines.

Depth perception

The ability to judge distances of objects and to see them in three dimension

Oculomotor cues

Depth perception cues involving the activity within the eyes

Convergence

Monocular cue of depth perception; the inward movement of the eyes that occurs when looking at something up close

Monocular cues

Cues that indicate depth or distance that can be seen within just one eye

Pictorial cues

Monocular cues that provide information about depth communicated through two dimensional pictures

Linear perspective

A depth perception cue where covering parallel lines suggest distance

Relative size

A pictorial cue based on size constancy suggesting that smaller objects are further away

Relative height

A pictorial cue based on the principle of size constancy , suggesting that taller objects are further away

Interposition

A depth perception cue, when an object or person blocks another, the one in the back is perceived to be further away

Texture gradient

A pictorial cue that assumes that objects within visible structure appear closer than those with little or no texture

Motion parallax

A depth perception cue, the sense that objects further away are moving more slowly

Binocular cue

A depth perception cue that involves the use of both eyes

Retinal disparity

Referring to the slightly different images seen by the right and left eye (due to distance between the two retinas) a primary binocular cue for depth perception

Perceptual illusions

An experience where the perception of a stimulus is different than the actual evoking stimulus

Literal visual illusions

Illusions that create images different from the objects or situations that make them

Physiological illusions

Illusions that result from excessive stimulations to the eyes or brain

Cognitive illusions

A type of visual illusion that involves higher order thinking, such as an individuals knowledge and assumptions about the world; examples include ambiguous or impossible pictures

The Müller-layer illusions

Perceptual illusion that has been shown to vary across cultures and as a result is one of the most well known and extensively researched perceptual illusions