Sensation and Perception AP Psychology

Sensation

The relationship between physical stimulation and its psychological effects.

Perception

How we recognize, interpret, and organize our sensations.

Detection threshold

Lets us to sense a stimulus.

Discrimination threshold

Lets us distinguish between different stimuli.

Absolute threshold

The minimal amount of stimulation needed to detect a stimulus and cause the neuron to fire 50 percent of the time.

Signal detection theory (SDT)

Predicts how and when we detect the presence of a faint stimulus.

Just noticeable difference (JND)

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

Weber's law

States that two stimuli must differ by a constant minimum percentage to be perceived as different.

Subliminal perception

A form of preconscious processing that occurs when we are presented with stimuli so rapidly that we are not consciously aware of them.

Tip-of-the-tongue phenomenon

Occurs when we try to recall something that we already know that is available but not easily accessible to consciousness.

Receptor cells

Located in sensory organs and are designed to detect specific types of energy.

Receptive field

An area from which our receptor cells receive input.

Transduction

Occurs when the receptors convert the input, or stimulus, into neural impulses, which are sent to the brain.

Contralateral shift

Occurs within the thalamus which redirects information to various sensory cortices in the cerebral cortex for processing.

Sensory encoding

The process by which receptors convey range information to the brain.

Single cell recording

A technique by which the firing rate and pattern of a single receptor cell can be measured in response to varying sensory input.

Visual sensation

Occurs when the eye receives light input from the outside world.

Distal stimulus

The object as it exists in the environment.

Proximal stimulus

The image of that object on the retina.

Cornea

A protective layer on the outside of the eye.

Curvature of the lens

Changes to accommodate for distance.

Retina

At the back of the eye and serves as the screen onto which the proximal stimulus is projected.

Rods

Sensitive in low light and detect black and white colors.

Cones

Sensitive to bright light and color vision.

Optic nerve

Transfers impulses to the visual cortex.

Optic chiasm

Sends information to the opposite side of the brain's visual field.

Serial processing

Occurs when the brain computes information step-by-step in a methodical and linear manner.

Parallel processing

Happens when the brain computes multiple pieces of information simultaneously.

Feature detector neurons

See different parts of the pattern such as a line set at a specific angle to background.

Young-Helmholtz or trichromatic theory

States cones in the retina are activated by light waves associated with blue, red, and green.

Opponent process theory

States that cells within the thalamus respond to opponent pairs of receptor sets.

Afterimage

Occurs when we stare at a set of colors for an extended period of time and the opponent color receptors fire to bring the eyes back into balance.

Color blindness

Occurs more in males and is mostly genetic.

Pinna

The ear lobe that collects sound waves and funnels them into the auditory canal.

Tympanic membrane

Also known as the ear drum, it vibrates due to sound waves.

Ossicles

Transfer vibrations from the tympanic membrane through the oval window.

Cochlea

A snail-shaped structure with cilia and fluid that picks up vibrations.

Auditory nerve

Sends information to the temporal lobe.

Vestibular sacs

Located in the inner ear, responsible for balance and sensation of tilting.

Place theory

Asserts that sound waves generate activity at different places along the basilar membrane.

Frequency theory

States that we sense pitch because the rate of neural impulses is equal to the frequency of a particular sound.

Conductive deafness

Refers to injury to the outer or middle ear structures.

Sensorineural deafness

Involves damage to the cochlea or the auditory cortex.

Olfaction

A chemical sense that sends information to the olfactory cortex and the limbic system.

Gustation

A chemical sense that sends information to the cerebral cortex, the hypothalamus, and the limbic system.

Cutaneous and tactile receptors

Skin receptors that consist of pressure, pain, and temperature receptors sending information to the medulla oblongata, the thalamus, and the somatosensory cortex.

Vestibular sense

Involves sensation of balance and is located in the semicircular canals of the inner ear.

Kinesthesis

Found in the joints and ligaments, transmits information about the location and position of the limbs and body parts.

Adaptation

An unconscious, temporary change in response to environmental stimuli.

Habituation

The process by which we become accustomed to a stimulus and notice it less over time.

Dis-habituation

Occurs when a change in the stimulus causes us to notice it again.

Attention

Refers to the processing through cognition of a select portion of the massive amount of information incoming from the senses and contained in memory.

Selective attention

Occurs when we try to attend to one thing while ignoring another.

Cocktail party phenomenon

Refers to our ability to carry on and follow a single conversation in a room full of conversations.

Divided attention

Occurs when we try to focus on more than one task at a time.

Perceptual process

Refers to how our mind interprets environmental stimuli.

Bottom-up processing

The brain's analysis and acknowledgement of raw sensory data.

Top-down processing

When the brain labels a particular stimulus or experience.

Visual perception

The need to perceive depth, size, shape, and motion.

Monocular depth cues

Cues that we need only one eye to see.

Relative size

Refers to the fact that images that are farther from us project a smaller image on the retina than do those that are closer to us.

Texture gradient

Refers to an object looking denser as distance increases.

Interposition

Occurs when a near object partially blocks the view of an object behind it.

Linear perspective

Occurs when parallel lines seem to draw closer together as the lines recede into the distance.

Binocular depth cues

Cues that rely on both eyes viewing an image.

Binocular disparity

Results from the fact that the closer an object is, the less similar the information arriving at each eye will be.

Visual cliff

Tests depth perception.

Proximity

The tendency to see objects near to each other as forming groups.

Similarity

The tendency to prefer to group like objects together.

Symmetry

The tendency to perceive preferentially forms that make up mirror images.

Continuity

The tendency to perceive preferentially fluid or continuous forms, rather than jagged or irregular ones.

Closure

The tendency to preferentially 'close up' objects that are not complete.