AP Psychology Unit IV: Sensation & Perception

Sensation

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

Bottom-up processing

Processing that begins in the sensory preceptors, then works up to the brain for integration and analysis of information. (Sensory preceptors → higher levels of processing.)

Top-down processing

Perceptions constructed from sensory input that draw on our experiences and expectations.

Selective attention

The focusing of conscious awareness on a particular stimulus. EX: hearing your name called from the crowd at a party.

Unintentional blindness

Failing to see visible objects when your attention is elsewhere.

Change blindness

Failing to notice change in your environment.

Transduction

The processing of receiving sensory stimulus and converting that stimulus into energy (neural impulses), and then delivering that information to the brain.

Psychophysics

The study of the relationships between physical characteristics of stimuli and our psychological experience of them.

Absolute threshold

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

Signal detection theory

Predicts how and when we detect presence of faint stimuli amid background stimulation. There is no level for everyone, it depends on peoples’ experiences, expectations, motivation, and level of fatigue.

Subliminal

Stimulus below one’s threshold for conscious awareness.

Priming

The (usually) unconscious activation of certain associations that influence one’s perception, memory, and response.

Difference threshold

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

Weber’s law

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

Sensory adaptation

Diminished sensitivity to a stimulus due to constant stimulation. Allows us to focus on informative changes in our environment.

Wavelength

Distance from peak to peak of a wave. Determines the hue of color.

Intensity

Amount of energy in a sound/light wave, what allows us to perceive it as loud/bright.

Cornea

Where light first enters the eye.

Pupil

A small, adjustable opening in the eye.

Iris

The colored muscle that controls the pupil and allows us to respond to our environment and emotions.

Lens

Transparent structure behind the pupil that changes shape to help focus the retina.

Retina

Light-sensitive inner surface of the eye, contains rods and cones and layers of neurons that help process visual information.

Accomodation

Process where the eye’s lens changes shape to focus on objects close to the retina.

Rods

Located in the retina, detect black & white, necessary for peripheral and night vision when cones don’t respond.

Cones

Concentrated near center of retina, function in well-lit conditions. Allow for fine detail and color sensations.

Bipolar cells

Neurons found in the retina, transmit signals from rods/cones to ganglion cells. Responsible for integrating and modulating signals from rods/cones.

Ganglion cells

Found in the retina, receive information from bipolar cells and transmit to the brain via the optic nerve. Responsible for color, contrast, and motion.

Optic nerve

Nerve that carries neural impulses from the eye to the brain.

Blind spot

The point where the optic nerve leaves the eye.

Fovea

Central focal point of the retina. (Cones cluster around it.)

Feature detectors

Nerve cells in the brain that respond to specific characteristics of stimulus such as shape or angle. Pass info along to supercell clusters.

Supercell clusters

Receive information from feature detectors, respond to more complex information. Certain clusters respond to particular types of stimulus.

Parallel processing

Processing multiple aspects of an issue simultaneously. Natural mode of processing for many functions.

Young-Hemholtz trichromatic theory

States the retina contains 3 different color receptors (red, green, and blue). When stimulated in combination they can produce any hue of a color.

Opponent-processing theory

States that opposing retinal processes enable color vision. EX: stimulated by red → seen as green.

Gesalt

Organized whole. The whole exceeds the sum of its parts.

Figure-ground

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

Grouping

Perceptual tendency to organize stimuli into coherent groups: proximity, continuity, closure.

Depth perception

The ability to see objects in 3 dimensions.

Visual cliff

A lab device used for testing depth perception in babies and animals.

Binocular cues

Depth cues such as retinal disparity that depend on the use of both eyes.

Retinal disparity

By comparing images from retinas of two eyes, the brain can figure out distance. The smaller the disparity the greater the distance.

Monocular cues

Depth cues such as interposition and linear perspective that are available to either eye alone.

Interposition

When one object is covering another object, it gives the perception that the partially covered object is further away.

Linear perspective

Visual cue where two parallel lines appear to meet together in the distance (like a railroad, for example).

Phi phenomenon

An illusion of movement created when lights are flickered on and off.

Perceptual constancy

Perceiving objects as unchanging even as illumination and retinal images change.

Color constancy

Perceiving familiar objects as having a consistent color even if changing illumination alters their wavelength.

Perceptual adaptation

The ability to adjust to an artificially displaced or invented visual field.

Foveal vision

Focused vision, visual acuity, sharp vision.

Audition

The highly adaptive sense/act of hearing.

Amplitude

Part of wave that determines volume.

Frequency

Part of wave that determines pitch.

Outer ear

Visible part of the ear, channels sound waves through the auditory canal.

Ear drum

Receives sound waves through auditory canal, vibrates to send them to the middle ear.

Middle ear

Receives sound vibrations from the middle ear and transmits them to the cochlea. The chamber between the eardrum and cochlea that contains 3 tiny bones (hammer, anvil, and stirrup) that concentrate vibrations.

Cochlea

Receives vibrations via the oval window from the middle ear, and jostle fluids to fill the baislar membrane and trigger neural impulses.

Hair cells

Bend due to vibrations from the baislar membrane and trigger nearby neural impulses that converge to form the auditory nerve.

Auditory nerve

Triggered by hair cell movement. Sends messages to the auditory complex of the temporal lobe via the thalamus.

Inner ear

Contains the cochlea, semicircular canals, and vestibular sacs.

Sensorineural hearing loss

Caused by damaged to the cochlea’s receptor cells or the auditory nerve. Also known as nerve deafness. Usually due to genetics, aging, or pro-longed exposure to loud noises (such as music).

Conduction hearing loss

Caused by damage to the system that conducts sound waves to the cochlea.

Cochlear implant

Converts sounds into electrical signals and stimulates the auditory nerve via electrodes threaded through the cochlea.

Place theory

Links the pitch we hear to the place where the cochlea is stimulated. Brain recognizes pitch by determining where the membrane generates the neural impulse, does not explain how we hear low-pitch sounds because they’re not so localized.

Frequency theory

States that the rate of nerve impulses travelling up the auditory nerve matches the frequency of the tone, and thus, the pitch. Doesn’t account for frequencies that are over 1,000 waves/second because a neuron cannot fire that fast.

Volley principle

By rapid succession, neurons can achieve a combined frequency of 1,000+ fires/second, helps to explain frequency theory.

Locating sounds

Sound waves strike one quicker and more intense the author which allows us to determine location.

Nociceptors

Sensory receptors that detect hurtful temperatures, pressure, or chemicals.

Gate-control theory

States that spinal chord contains neurological “gate” that blocks or allows pain signals to pass to the brain.

Opening the gate

Pain signals travelling up small nerve fibers.

Closing the gate

Large fibers or information coming down from the brain.

Biological influences of pain

Activity in spinal chord, genetic differences in endorphin production, brain’s interpretation of CNS activity.

Psychological influences of pain

Attention to pain, learning based on experience, expectations.

Socio-cultural influences of pain

Presence of others, empathy towards others’ pain, cultural expectations.

Basic tastes

Salty, sweet, sour, bitter, umami.

Kinesthesia

System that allows us to sense body position and movement of an individual body part.

Vestibular sense

Sense of body movement and balance.

Semicircular canals

Part of the inner ear that contains fluid that moves when your head tilts. Related to vestibular sense.

Vestibular sacs

Sacs that connect the semicircular canals to the cochlea. Helps stimulate hair cells and send messages about balance/movement to the cerebellum.

Sensory interaction

The principle that one sense may influence another.

Embodied cognition

Influence of body sensations, gestures, and other states on cognitive preferences and judgement.

Perceptual set

A mental predisposition to perceive one thing and not another.

Schemas

Concepts formed through experience that organize and allow us to interpret unfamiliar information.

Organ of Croti

Structure in the cochlea that produces nerve impulses in response to vibrations.

Papillae

Taste buds

Motion parallax

A type of depth perception cue in which objects that are closer appear to move faster than objects that are far away. A monocular cue.