AP Psychology Unit 1B: Perception and Sensation

Absolute Threshold

Minimum stimulation needed to detect stimulus 50% of the time

Weber’s Law

Able to tell the difference between degrees of stimulation; two stimuli must differ by constant minimum percentage

• Light: change intensity of 8%

• Weight: change by 2%

• Frequency: change by 0.3%

Transduction

 The transformation of one form of energy to another

Thalamus

Filters and integrates sensory information

Sensory Interaction

One sense can influence another– can alter perception or “mix”

Attention

Process of focusing on one aspect of an environment (while ignoring the rest)

Selective Attention

Conscious awareness on particular stimulus (voluntary focus)

Divided Attention

Processing two or more demands/focuses at the same time

Cocktail Party Effect

Ability to attend to only one voice within a group or many

Inattentional Blindness

Failing to see objects when our attention is directed elsewhere

Change Blindness

Failing to  notice changes in the environment

Basic Eye Anatomy

CORNEA; eye’s color and protective outer-layer, PUPIL; small opening (hole) where light enters, IRIS; ring of muscles tissue that forms color portion of the eye (contracts/expands=size of pupil), lens, and retina

Lens

Transparent structure behind pupil that focuses images into retina

Retina

Contains receptor rods and cones (also layers of neurons); light waves transduce into neural impulses via rods and cones

Rods

Receptors detecting black, white, and ray, and are sensitive to movement

Cones

Bear center of eye, interprets light as color, and functions best during daylight

Fovea

Focal point of retina where most cones are located

Blindspot

Optic disk is point at which the topics nerve leaves the eye; area where no respectors are to interpret light

Occipital Lobe (Visual Cortex)

Receives, processes, and interprets visual information from the eyes

Color Vision Theories

Trichromatic theory and opponent-process theory

Color Deficiency

Person has difficulty distinguishing color(s) because of the absences of certain cones

Opponent-Process

Seeing the opposite of the stimulus; green → red, blue → orange, etc.

Afterimages

When looking at a bright/colored image, your brain adjusts to the intensity, when you look away your brain readjusts to the new background, but the adjustment time creates the afterimages as the colors linger

Dichromatism

A colorblind individual can see two different colors, but not the rest

Trichromatic

A person can see all three colored visions (red, green, and blue); “normal” vision

Monochromatism

A person can see one color but the whole spectrum of said color; light gray, gray, dark gray.

Light-Dark Adaptation

Eyes adjust to both light/lack of light by decreasing/increasing the sensitive of photoreceptors

Nearsightedness (Myopia)

Lens focuses in front of retina

Farsightedness (Hyperopia)

Lens focuses light past the retina

Accommodation

Lens changes curvature and thickens to focus rays

Prosopagnosia

Neurological disorder preventing peope from recognizing faces

Blindsight

People with damage to visual cortex can still respond to stimuli without being consciously aware of seeing something

Basic Ear Anatomy

Cornea (protective layer + focus light), iris (control light entry), pupil (hole for light), lens (further focuses light to retina), retina (light converted to neural signals via rods and cones)

Hair Cells

Special sensory receptors in inner ear (cochlea) used for hearing and balance

Cochlea

Consisting of tiny hairs which transduce vibrations → electrical signals 

• Signals → thalamus → auditory cortex

Ossicles

Three tiny bones (malleus, incus, and stapes) that make up the inner ear; amplify sound and transmit vibrations to inner ear

Tympanic Membrane (Eardrum)

Collects sound waves

Sound Localization

Brain’s ability to determine origin of sound

Sound Waves

Vibrations carrying pitches and volumes

Wavelength

Distance between peaks of sound and light waves

Amplitude

Volume of sound

Hearing Impairment

Hearing loss (damage to outer/middle ear) or sensorineural hearing loss (damage to inner ear/auditory nerve)

Conduction Deafness

Motion through outer or middle ear hindered or bones became too rigid to carry sound)

Sensorineural Deafness

Damage to cochlea, hair cells, or auditory nerve

Pitch Theory

Sound waves frequency/wavelength

• Higher pitch = shorted wavelength

Frequency Theory

Rate of nerve impulse traveling in auditory nerve indicates tonal frequency

Place Theory

Pitch related to where cochlea is stimulated explains high pitches

Volley Principle

Neural cells can alternate firing to reach frequencies above 100 waves per second any sound over 100 hertz

Touch

 Skin receptors transduce touch stimulus 

• “Hot” sense triggers both hot and cold receptors

• Same receptors creates different sensations; tickled v. itches

Gate-Control Theory

Spinal cord contain “gate” that either blocks pain signals or allows them to send to the brain (opened by small fibers, closed by activity in large fibers

Phantom Pain

Brain misinterprets information to interpret movement or pain from last limb

Vestibular Sense

Sense of balance; calcium crystal filled vestibular sacs; movement → hair-like receptors → message to cerebellum

Semicircular Canals

Fluid filled space in ears

Kinesthetic Sense

Sense of movement and coordination; interactions between sensors in muscles, tendons, joints, and vision; largely directed by the cerebellum

Gustatory Sense(s)

Sweet, salty, sour, bitter, umami (meat), and oleogustus (fat)

Olfactory Sense

Receptors at top of each nostril detect odor molecules; bypasses the thalamus

Anosmia

Not being able to smell; loss of smell

Pheromones

Chemical messages detected by your olfactory system

Synesthesia

Experience a stimulus as another stimulus; color as sound

Sensations

Sensory receptors and NS represent and interpret stimulus

Perception

Organize stimuli and interpret information which enables recognition of objects and events

Sensory Adaptation

Lesser sensitivity as consequence of constant stimulation

Habituation

Learned ability to ignore a stimulus

Perceptual Set(s)

Tendency to perceives things based on past experience, expectation, and current mental state

Schemas

Frameworks from which we understand the world; understanding of how the world should work; world expectations

Gestalt Principles

An organized image; full picture

Figure-Ground Perception

Distinguish object (figure) from a background (ground); separating elements into near/fa

Closure

Gestalt principle; brain perceives incomplete visual information as a whole; fills in the blank

Similarity

Tendency to group objects that share similar features

Proximity

Tendency to group objects that are close to each other

Visual Cliff Research

Babies “walk off” cliff/onto glass because pattern is the same; teaches us that depth perception is LEARNED

Perceptual Constancy

Perceive objects as unchanging even as illumination and retinal images change (top-down processing)

Size Constancy

Objects as having an unchanging size

Shape Constancy

We perceives form of familiar objects the same

Color Constancy

Perceiving familiar objects as having constant color, even when illumination changes; the color physically stay the same even when the lights are turned off, our brain knows that

Monocular Depth Cues

Perceives depth using only one eyes

Relative Clarity

Hazy/blurry objects are typically further away than sharp/clear objects

Relative Size

Far objects appear small; Close objects appear big

Texture Gradient

Gradual change from distinct features to indistinct features when increasing distance

Linear Perspective

Parallel lines converge as they go into the distance → creates depth

Interposition

An object blocking another must be closer to you

Binocular Depth Cues

Both eyes see in three dimension

Retinal Disparity

Difference between eyes

Convergence

Eyes move inward as objects move closer to you

Reversible Figure

Seeing two images from one image; old lady v. young lady

Color Afterimages

Seeing the opposite of a color as an afterimage when you look away

Illusions of Apparent Motion

Things appear to move, even when they aren’t movin

Phi Phenomenon

Perceives two adjacent (stationary) lights blinking on/off quickly as one movement (back/forth)

Stroboscopic Movement

Brain perceives rapid series of slightly varying images as continuous movement