Sensation and Perception

Receptors

Specialized cells that convert physical energy in the environment to electrical energy that can be transmitted as nerve impulses to the brain

Transduction

Conversion of 1 form of energy to another (sensory receptors are biological transductors)

Sensory Adaptation

Repetitive/unchanged stimulation eventually disappears due to adaptation (ex.: perfume smell, cold water in a pool, food smells at a restaurant, noise of a projector, etc.)

Sensory Interaction

How senses influence one another (smell & taste have the most interaction between each other)

McGurk Effect

“Ba vs. Fa;” seeing mouth movements helps dictate what we hear (interaction between vision & hearing)

Synesthesia

Brain circuits of 2+ senses are jointly d& stimulation from 1 sense triggers an experience in another (ex.: auditory-tactile, Grapheme-color, sound-color, number-form); could be cause by genetics, faulty pruning, etc.

Light & the Visual Spectrum

• The color something appears is the light that is reflected off of it

• Light waves=energy from environment

Cornea

Part of eye; transparent, protective outer coating; works w/ lens to collect and focus light rays

Pupil

Part of eye; opening in eye (lets light in)

Iris

Part of eye; controls amnt. light that enters eye (like a camera shutter)

Lens

Part of eye; focuses incoming light on retina (contacts/glasses assist the lens)

Accommodation

Process of curving lens to project images on retina; muscles behind iris change lens shape (flattens to focus on distant objects; thickens to focus on closer objects)

Retina

Photoreceptive portion of eye

Rods

Type of photoreceptor in retina; about 100 million/eye; VERY light sensitive; deals with night vision; deals with black & white info; concentrated at periphery of eye

Cones

Type of photoreceptor in retina; about 6.5 million/eye; good in bright light (NOT in dark); helps perceive color (150-200 diff. colors); good with discerning details; concentrated in fovea (center of eye)

Fovea

Center of macula (pt. of retina that provides sharp, central vision); only contain cones; sharpest pt. of vision in eye

Bipolar cells

Connect rods/cones to ganglion cells

Ganglion Cells

Neurons in retina that gather info from receptor cells; axons of ganglion cells make up optic nerve

Optic Nerve

Part of eye; nerve tat leads to thalamus & then brain’s occipital lobe (occipital lobe is located @ back of head & intérprete optic nerve impulses)

Blindspot

Area on retina w/o receptors (place where optic nerve is in eye)

Feature Detectors

Cells in visual cortex that are sensitive to specific features (horizontal, vertical, angled lines); image that reaches brain is combination of lines/angles that somehow form a pattern that makes sense to brain

Normal Vision

Rays of light converge on retina of normal eye

Nearsightedness

Eyeball is longer than normal—>visual info focuses closer in front of retina—>faraway objects are blurry

Farsightedness

Eyeball is shorter than normal—>visual info focuses behind retina—>nearby objects are blurry

Trichromatic Theory

Color vision theory; all colors of light are made up of red, green, and blue; retina only has 3 cone types that correspond to these colors of light

Opponent Process Theory

Color vision theory; as the visual image leaves receptor cells, we analyze it in terms of 3 sets of opposing colors (red-green, blue-yellow, black-white); visual systems treat pairs of colors as opposing/antagonistic; when fatigued, the opposite color fills in

Afterimage Effect

Burst of neuron firing is produced when a color is removed; opposite color fills in

Monochromatism vs. Dichromatism (Color Blindness)

• Monichromatism=type of color blindness in which one can only see 1 color (instead of “trichromatic”)

• Dichromatism=type of color blindness in which one can only see 2 colors (instead of “trichromatic”)

• Color blindness is a recessive trait carried on X chromosome; b/c males only have 1 X (females have 2), color blindness is much more common in men

• Most common color blindness is red-green color blindness

Prosopagnosia

“Face blindness;” inability to recognize any familiar face

Blindsight

Blind ppl. respond to items displayed in their blind area, where they can’t consciously see them; nerves send visual info to brain areas that don’t help with conscious vision, but may cause blindsight

Pitch

Measure of frequency of a sound wave (Hz or “vibrations/sec”)

Loudness

Measure of amplitude of a sound wave

Function of Outer Ear

Collects sound waves

Pinna

Part of outer ear; outer flap & cartilage that receives sound waves

Auditory Canal

Part of outer ear; canal directly inside ear

Function of Middle Ear

Amplify sound waves

Tympanic Membrane (Eardrum)

Part of middle ear; piece of skin stretched over entrance to ear; vibrates to sound

Ossicles (Hammer (Malleus), Anvil (Incus), Stirrup (Stapes))

Part of middle ear; 3 bones that transfer sound waves to cochlea (also called ossicles)

Eustachian Tubes

Part of middle ear; tube connecting throat & mouth to ear; helps maintain air pressure

Cochlea

Part of inner ear; filled w/ fluid & small hairs that vibrate to incoming sound

Basilar Membrane

Part of inner ear; runs through cochlea; hair cells are attached here

Semicircular Canals

Part of inner ear; help with balance

Conduction Deafness

Happens if hammer, anvil, or stirrup are damaged/become more brittle; often happens w/ age; can be helped w/ hearing aid (amplifies sound)

Sensorineural Deafness

Happens w/ damage to hair cells/auditory nerve; can’t be helped w/ hearing aid; can be caused by loud sounds

Place Theory

Hearing theory; diff. frequencies cause larger vibrations @ diff. locations along basilar membrane; explains that higher pitch sounds are interpreted based on where hair cells are more active

Frequency Theory

Hearing theory; basilar membrane vibrates @ same frequency as the sound wave; explains low frequency/pitch sounds BUT doesn’t explain high-pitch sounds, due to limit in neuron firing speed

Volley Theory

Hearing theory; neurons alternate firing to process highest pitch sounds

Interaction Between Place Theory, Frequency Theory, & Volley Theory

• Place Theory explains high pitched

• Frequency Theory (w/ help from Volley Theory) explains low pitches

• Place Theory & Frequency Theory together help w/ medium pitches

Taste/Gustation Overview

• Taste is a chemical sense

• Taste exists for our pleasure

• Bumps on the tongue=fungiform papille

• Fungiform papille have taste buds that have taste receptors

• Taste receptors reproduce in 1-2 weeks

• We recognize 5 basic tastes: sweet, sour, salty, bitter, umami, oleogustus

• Taste cells respond to all tastes, but certain taste cells are somewhat specialized

Survival Function of Sweet Taste

Energy source

Survival Function of Salty Taste

Sodium; essential to physiological processes

Survival Function of Bitter Taste

Potential poisons

Survival Function of Sour Taste

Potential toxic acid

Survival Function of Umami Taste

Proteins to grow/repair tissue

Survival Function of Oleogustus Taste

Fats for energy, insulation, cell growth

Gustatiry Pathway

• Gustation keeps poisons out of digestive system

• Stimuli from taste are dissolved in saliva

• Short hair-like structures (microvilli) come into direct contact w/ saliva & send electrical signal to brain stem—>thalamus—>gustatory cortex (in the insular cortex, which separates temporal lobe from frontal & parietal)

Testers (Non, Super, Medium)

• Non-tasters=lessened sense of taste

• Super tasters=have more taste buds & can taste more than the average person

• Medium tasters=normal tasters

Smell/Olfaction

• Most direct route to brain (bypasses thalamus)

• Receptor cells (called olfactory cells) are stimulated by gassed dissolved in fluid of membrane

• Olfactory cells regenerate every 30-60 days

• For something to smell, it must be dissolvable in water

• Odors trigger combos of receptors—>patterns interpreted by olfactory cortex

• Nerve impulses—>sent to olfactory bulb (just below frontal lobe; by passes thalamus)—>impulse transfers to area in temporal lobe—>impulse transferred to limbic system

• Large connection between certain smells, emotions, memories

Pressure

• Pacinian corpuscle receptors help us perceive pressure

• If pressure is constant, adaptation takes place & there’s a reduction/halt in signal

Temperature

• ONLY have receptors for warm/cold

• Feeling something cold←hot or cold stimulus

• Feeling something warm←warm stimulus

• Feeling something hot←warm/cold spots simultaneously stimulated

Pain Overview

• Free nerve endings throughout body (called nociceptors) detect hurtful temp., pressure, chemicals, etc. (found in muscles, skin, membranes, around bones, joints, organs, etc.)

• A-delta pain fibers=deal with sharp/immediate pain; myelinated, fast-conducting neurons; activated by strong physical pressure/temp. extremes; conducts info from spinal cord→thalamus→sensory cortex

• C pain fibers=deal with chronic, steady, dull pain; un-myelinated, slow-conducting neurons; activated by chemical changes in tissue when skin is damaged; conducts info from spinal cord→thalamus→many brain areas (including frontal lobe)

Influences on Pain

• Substance P=pain neurotransmitter

• Endorphins can inhibit substance P

• Psychological factors (distraction, expectation, learning, emotions (anxiety, fear, etc. can increase pain/signal gates to open))

• Sociocultural (presence of others, empathy, cultural expectations, etc.)

Gate Control Theory

Pain perception theory; pain is controlled by “gates” in spinal cord (open=pain; closed=no pain)

Phantom Limb Syndrome

When normal sensory input is absent brain may misinterpret & amplify random nervous system stimulation (pain, movement experiences, sensation experiences, etc.); phantoms can impact other senses too

Kinesthetic Sense

• Deals w/ location & position

• Proprioceptors help w/ kinesthetic sense (located in muscles/joints)

Vestibular Sense

• Deals w/ balance/equilibrium

• Vestibular sense responds to changes in gravity, motion, body pos.

• Fluid-filled semicircular canals & vestibular sacs in inner rear respond to changes

• Vestibular sense works w/ eyes; problems arise when info between eyes conflict

Absolute Threshold

Minimum threshold of stimulus needed for the change to be detected (50% of the time)

Difference Threshold/Just Noticable Difference (JND)

Smallest possible difference between 2 stimuli that can be detected ½ the time

Weber’s Law

Size of JND varies depending on its relation to strength of original stimulus; size of JND is proportionate to original stimulus (bigger stimulus needs big change to be noticed; smaller stimulus needs small change to be noticed)

Selective Attention

Focusing of attention on selected aspects of environment & blocking out of others

Cocktail Party Phenomenon

In noisy places, auditory cortex boosts some sounds into help brain prioritize what’s important

Inattentional Blindness

Failing to see visible objects when attention is directed elsewhere

Change Effect/Change Blindness

Failing to notice changes in environment

Priming

Activation (often unconsciously) of certain associations, thus predisposing one’s perception, memory, response

Top Down Processing

Info @ high lvls. of processing can influence lower, earlier levels (expectations guide perception); related to perceptual set, culture, motivations emotions, prior knowledge, etc.

Bottom Up Processing

Lower to higher processing lvls.; NOT influenced by expectations/experiences

Motion Aftereffects

Look @ moving objects for a while→look @ something stationary→illusion of new scene moving in opp. dir. (waterfall effect, etc.)

Motion Parallax

Near objects seem to move more quickly in opp. dir. of our mvmnt., while far away objects seem to move more slowly

Induced Movement

Ex.: if you’re in a parked car & another car next to you moves, you feel like you’re moving (frame of reference is tricked)

Stroboscopic Movement

Movies, etc. that have one rapidly view a series of slightly varied still images

Phi Phenomenon

Illusion of mvmnt. that occurs when 2+ adjacent objects blink on/off in quick succession

Perceptual Constancy

Ppl. correctly perceive objects as constant in shape, size, color, lightness despite raw sensory data that could mislead; brain must compute ratios (size, shape, color, lightness despite raw/brightness, etc.)

Binocular Depth Cues

Depth cues involving both eyes

Binocular Disparity/Retinal Disparity

Type of binocular depth cue; brain has 2 diff., but overlapping retinal images; disparity is used to compute distances of nearby objects (ex.: camera 1/camera 2; looking at object while switching which eye you look through makes it appear to change location; etc.)

Convergence

Type of binocular depth cue; retinal images are combined by brain (ex.: floating sausage finger perception when putting fingers together & looking over top of them)

Monocular Depth Cues

Depth cues involving 1 eye (pictorial depth cues, etc.); often used by artists (da Vinci, etc.)

Interposition/Occlusion

Type of monocular depth cue; near objects block far objects

Relative Size

Type of monocular depth cue; far off objects are smaller than closer ones on retina

Relative Clarity

Type of monocular depth cue; more light passes through object that are farther away→objects are viewed as hazy, blurry, unclear; nearby objects are sharp/clear

Linear Persoective

Type of monocular depth cue; parallel lines appear to converge @ a distance

Texture Gradient

Type of monocular depth cue; there’s a continuous change in uniformly textured structures (as surface recedes, texture becomes denser/viewed almost as smooth)

Gestalt

“Organized whole”

Proximity

Gestalt; when elements are placed close together, they tend to be perceived as a group

Similarity

Gestalt; objects that look similar are perceived as group/pattern (“one of these things is not like the other”)

Continuity

Gestalt; eye is compelled to move through 1 object & continue to another

Closure

Gestalt; when an object is incomplete, we perceive the whole by filling the gaps

Figure/Ground

Gestalt; when identifying a figure, we assign the rest of the scene to background

Ames Boxes/Ames Rooms

Albert Ames created rooms that played w/ linear perspective & other distance cues; a diagonally cut room could appear rectangular due to crooked windows/floor tiles; room creates illusion that 2 objects placed on either side are equidistant from viewer & 1 object looks much bigger than the other