REVIEW (Unit 3) - Sensation and Perception

Sensation

Sensation

The process by which we receive physical energy from the environment and encode it into neural signals.

Perception

The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Gestalt

A movement/school of thought in psychology founded in Germany in 1912, seeking to explain perceptions in terms of gestalts (or an organized whole) rather than by analyzing their constituents (or individual parts).

Gestalt Laws of Perceptual Organization

Provide a set of principles for understanding some of the ways in which perception works.

Similarity

Similar things tend to appear grouped together (both visual and auditory stimuli).

Pragnanz ("Good Figure" or Simplicity)

Objects in the environment are seen in a way that makes them appear as similar as possible.

Proximity

Things that are near each other seem to be grouped together.

Continuity

Points that are connected by straight or curving lines are seen in a way that follows the smoothest path.

Closure

Things are grouped together if they seem to complete some entity.

Common Region/Grouping

Elements that are grouped together within the same region of space tend to be grouped together.

Figure-Ground

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

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

Cues that help us judge distance and require the use of both eyes.

Retinal Disparity

Each eye sees a slightly different image because they are about 6 cm apart (on average).

Convergence

When looking at a close-up object, your eyes angle inwards towards each other.

Monocular Cues

Cues that help us judge distance and only require the use of one eye.

Linear Perspective

Parallel lines appear to converge at a vanishing point on the horizon.

Interposition

The partial blocking of one object by another object, leaving the viewer with the perspective that the blocking object is closer.

Relative Size

If two objects are roughly the same size, the object that looks the largest will be judged as being the closest to the observer.

Relative Height

We perceive objects higher in our field of vision as farther away.

Relative Clarity

Clear objects appear closer than blurry or fuzzy objects.

Light and Shadow

Nearby objects reflect more light to our eyes than distant ones.

Texture Gradient

When looking at an object that extends into the distance, the texture becomes less and less apparent the farther it goes into the distance.

Motion Parallax

Objects closer to us appear to move faster than those farther away.

Phi Phenomenon (Stroboscopic Movement)

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

Relative Motion

As we move, objects that are actually stable may appear to move.

Perceptual Constancy

Our ability and need to perceive objects as unchanging even as changes may occur in distance, point of view, and illumination.

Color Constancy

Perception that the color of an object remains the same even if lighting conditions change.

Size Constancy

Tendency for the brain to perceive objects as the same apparent size regardless of their distance from us.

Shape Constancy

When our viewing angle changes or an object rotates and we still perceive the object as staying the same shape.

Lightness Constancy

When our perception of the whiteness, blackness, and grayness of objects remains constant no matter how much the illumination has changed.

Top-Down Processing

Information processing guided by our thoughts or higher-level mental processes - we move from the general concept to the specific example.

Bottom-Up Processing

Information processing that starts by noticing individual elements and then zooms out to appreciate the whole picture.

Transduction

The conversion of one form of energy into another. In sensation, this is the transformation of sights, sounds, and smells into neural impulses our brain can interpret.

Absolute Threshold

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

Difference Threshold (Just Noticeable Difference or JND)

The minimum difference between two stimuli required for detection 50% of the time.

Signal Detection Theory

Your ability or likelihood to detect some stimulus is affected by the intensity of the stimulus and your physical and psychological state.

Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation.

Gustav Fechner

German philosopher and psychologist who founded the field of psychophysics and studied synesthesia.

David Hubel and Torsten Wiesel

Harvard University researchers who received the Nobel Prize for their discoveries about information processing in the visual system.

Ernst Weber

Noted for Weber's Law, which states that stimuli must differ by a constant "proportion" to be perceived as different.

Perceptual Set

A mental predisposition to perceive or notice some aspects of the available sensory data and ignore others.

Schema

Mental filters or maps that organize our information about the world.

Context Effects

Describes the influence of environmental factors on one's perception of a stimulus.

Cultural Effects

Not all cultures perceive the same stimuli in the same way.

Divided Attention

Focusing on two or more tasks or stimuli.

Selective Attention

The process of directing our awareness to relevant stimuli while ignoring irrelevant stimuli in the environment.

Cocktail Party Effect

The ability to focus your hearing on one specific thing even though noise is all around you.

Stroop Effect

Our brains recognize the color of the word first, which interferes with our ability to read the word aloud.

Inattentional Blindness

Failing to see visible objects when our attention is directed elsewhere.

Change Blindness

The inability to see changes in our environment when our attention is directed elsewhere.

Wavelength

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

Amplitude

The wave's height, which measures the intensity of the wave.

Pupil

The adjustable opening in the center of the eye through which light enters.

Iris

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

Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

Retina

The light-sensitive inner surface of the eye that contains the receptor rods and cones.

Rods

Retinal receptors that detect black, white, and shades of gray.

Cones

Retinal receptors that detect colors and details.

Fovea

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

Bipolar cells

Specialized neurons that connect the rods and cones with the ganglion cells.

Ganglion cells

Specialized neurons that connect to the bipolar cells and form the optic nerve.

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 there are no receptor cells located there.

Feature Detectors

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

Parallel processing

The brain's natural mode of information processing many things at once, such as color, motion, form, and depth.

Young-Helmholtz trichromatic theory

The theory that the retina contains three different color receptors (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 enable color vision.

Acuity

Sharpness of vision.

Nearsightedness/Myopia

A condition in which nearby objects are seen clearly but distant objects are blurred.

Farsightedness/Hyperopia

A condition in which distant objects are seen clearly but nearby objects are blurred.

Prosopagnosia/Face Blindness

A neurological condition characterized by the inability to recognize faces.

Agnosopsia/Blind Sight

A perceptual phenomenon that occurs when people who have blindness due to damage to the primary visual cortex can still respond to visual stimuli.

Cataracts

A clouding of the eye's lens which results in vision difficulties.

Illusion

A sensory distortion that can fool a person's senses.

Frequency

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

Pitch

A tone's highness or lowness.

Amplitude

The strength of a wave.

Audition

The sense of hearing.

Outer ear

The part of the ear that traps sound waves and channels them through the auditory canal to the eardrum.

Pinna

The fleshy outside part of the ear.

Auditory canal

The canal in the outer part of the ear down which sound waves travel.

Eardrum

The tight membrane that vibrates when sound waves hit it.

Middle ear

The part of the ear that transmits the eardrum's vibrations to the cochlea.

Inner ear

The innermost part of the ear that contains the cochlea, semicircular canals, and vestibular sacs.

Basilar membrane

A membrane inside the cochlea that vibrates in response to sound.

Auditory nerve

The nerve that sends neural messages to the temporal lobe's auditory cortex.

Place theory

Links pitch we hear with the place where the cochlea’s membrane is stimulated.

Frequency theory

States that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

Volley principle

Neural cells alternate firing in rapid succession to achieve a combined frequency.

Conduction hearing loss

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.

Sensorineural hearing loss

Hearing loss caused by damage to the cochlea's receptor cells or auditory nerves.

Cochlear implant

A device for converting sounds into electrical signals and stimulating the auditory nerve.

McGurk Effect

A perceptual phenomenon demonstrating an interaction between hearing and vision in speech perception.

Gustation

The sense of taste, including the 5 basic tastes:sweet, salty, sour, bitter, and umami.

Papillae

Structures on the tongue where taste buds are located.

Sensory Interaction

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

Olfaction

The sense of smell.

Odorants

Chemical compounds that have smell.