MCAT Foundation: 6-10

Visual Cues:

sensory cues that are perceived by the eyes or vision

Monocular Cues

cues that we do not need two eyes for (relative height/size)

Binocular Cues:

cues that we need two eyes for convergence of retention disparity (depth)

binocular

depth requires _______ vision 

parvo pathway

a visual pathway in the brain responsible for processing fine details, color, and static objects

Motion:

high temporal resolution, Magno pathway 

Constancy:

perception of objects as the same, size, shape, color despite positional changes 

Sensory Adaptation:

change in the sensitivity of your perception of a situation

decrease in responsiveness with constant stimulus

Somatosensory Homunculus:

cortical map in primary somatosensory cortex 

Thermoception:

the perception of temperature and temperature change by organisms 

Mechanoception:

the perception of mechanical stimuli (touch and pressure)

Nociception:

the perception of pain (TRPV 1 receptors) 

Proprioception:

the perception of position

Kinesthesia:

the awareness and conscious movement of the body

Weber's Law:  

a larger baseline means larger change needed to notice a difference 

just noticeable difference of stimulus/ initial intensity  

(∆I / I) = k

Absolute threshold of sensation:

minimum stimulus needed to be detected 50% of the time

Gestalt Principle:

why we perceive things the way we do 

Law of Similarity

items that are similar are grouped together 

Law of Pragnanz:

humans perceive complex or ambiguous stimuli in the simplest, most stable, and most orderly way possible

Law of Proximity:

objects that are close together are grouped together 

Law of Continuity:

lines are seen following the smoothest path 

Law of Closure:

a Gestalt principle of perception where the brain mentally fills in the gaps of an incomplete image or shape to perceive it as a whole and complete form

Vestibular System:

system enclosed within the ear that allow for understanding of rotation and position

Semicircular canals:

detect rotational acceleration

Otolith organs:

detect linear acceleration and head position

Signal Detection Theory:

how we make decision under uncertain circumstance, distinguishing real signal vs noise

d prime siganls

sensitivity  

If d’ is larger the task was easier 

If d’ is smaller the task was easier

beta signals

decision criterion  

Bottom-up Processing:

sensory input drive perception (data driven) 

Top-Down Processing:

prior knowledge and expectations influence perception (concept-driven) 

Meissner’s Corpuscle:

type of mechanoreceptor in the skin that detects light touch and low-frequency vibrations

Pacinian Corpuscle:

an encapsulated ending of a sensory nerve that acts as a receptor for pressure and vibration

Merkel’s disk:

specialized mechanoreceptors in the skin that detect light touch, pressure, shape, and edges are slow adapting 

Ruffini endings:

specialized sensory receptors in the skin that detect skin stretch, pressure, and joint position

Scalera:

white part of the eye, thick fibrous tissue that forms the substance of the eye 

Cornea:

the part of the eye that focus light, is protected 

Conjunctiva:

series of nerves that protects the cornea 

Aqueous humor:

water chamber of the eye

Lens:  

biconvex that changes shape by ligaments depending on the light received “fine tunes” 

Iris:

the colored part of the eye that can constrict or dilate 

Pupil:

the hole controlled by the iris, (opens=dark) (closes=light)

Retina

the photoreceptors in the eye 

Optic Nerve:

fibers from the retina in the brain 

Chorid:

blood vessel system that nourishes the eye 

Rods:

120M, very light sensitive, turned on receptors that turn off when the light reaches the eye, peripheral vision with slow recovery 

Cones:

6M, recognize color, concentrated in the back of the eye (foeva), fast recovery

Foeva:

center of the macula, sharpest vision 

Visual field Processing:

nasal retina crosses at optic chiasm

Left visual field → right brain → right field → left brain 

Parallel Processing:

simultaneous analysis of color, motion, form, and depth

Outer Ear:

pinna, ear canal to tympanic membrane 

Middle Ear:

ossicles (malleus, incus, stapes) → oval window 

Inner Ear:

cochlea, semicircular canals 

Mechanoelectrical signal:

hair cells in cochlea when endolymph moves 

Basilar Tubing:

tonotopic map, cochlea to cortex 

Odorants:

olfactory epithelium → olfactory bulb → higher brain center (bypasses thalamus) 

Pheromones:

chemicals triggering innate unconscious responses in others 

Gustation

five tastes, with taste buds in papillae 

Papillae:

fungiform (front), foliate (sides), circumvallate (back)

Alert State:

beta waves 

Relaxed State:

alpha waves

N1 stage

(theta waves, hypnic jerks, hallucinations) 

N2 stage

(theta waves, sleep spindle (memory consolidation and sensory processing), K complex)

N3 stage

(delta waves, slow-wave sleep, deep)

REM

(beta wave, dreaming, memory consolidation, muscle atonia)

Brain waves

based on frequency and associated with states of consciousness 

K complex

a waveform observed in the brain's electrical activity, high voltage peak followed by a slower positive wave, suppressing arousal

Freud Dream Theory 

Manifest (actual image of a dream upon waking) vs. Latent (hidden psychological meaning behind events)

Activation-Synthesis:

brainstem activation + cortex interprets random signals

Depressants:

lower CNS activity and increase the production and GABA neurotransmitter (alcohol, barbiturates, benzodiazepines) 

Opiates:

pain relief that mimic endorphin release (morphine and heroin) 

Stimulants

increase dopamine and norepinephrine (amphetamines, cocaine, caffeine, nicotine

Hallucinogens:

alters perception and mood (LSD, marijuana, ecstasy)

Oral (slowest),  Inhalation, Injection (fastest), transdermal

Route of Entry (drugs)

Exogenous cues:

external stimulus  (loud sound)

Endogenous cues:

internal stimulus (meaningful cue) 

Divided Attention:

ability to perform more than one task 

Selective Attention:

the focusing on one stimulus while ignoring others, “attention filter” , only certain information can enter conscious awareness

Broadbent’s Early Selections Theory:

sensory input → sensory register → selective filter → perception → consciousness (not accepted)

Deutsch Late Selection:  

stimuli is processed for meaning before filtering (not accepted) 

Preismans Attenuation Theory:

sensory input → attenuator (weakens but doesn’t eliminate) → perception (accepted) (cocktail party)

Inattentional Blindness:

failure to notice an unexpected stimulus when attention is focused elsewhere, missing something entirely

Change Blindness:

failure to notice changes in environment, missing a change 

Spotlight Model:

attention acts like a spotlight, shifts in attention are cognitive not necessarily physical movement of the eyes

Sensory Memory:

very short, if attended goes to working memory 

Ionic:

visual ( < 1 sec) 

Echoic sensory memory

the brief, temporary sensory memory that holds auditory information for about 2–4 seconds after a sound has ended

Working Memory:

short-term memory, 7 + 2 items, duration -15-30 secs, if rehearsed stored in long term memory

Phonological:

words/numbers

Visuospatial sketchpad: 

mages/maps 

Central executive: 

integrates information

Long term Memory:

unlimited capacity for information

Explicit:

declarative 

Episodic: 

type of explicit memory that stores personal experiences 

Semantic:

a type of explicit memory that stores facts, concepts, knowledge

Implicit:

non declarative (unconscious recall)

Procedural:

a type of implicit memory for skills and habits 

Priming:

a type of implicit memory for prior exposure and influences

Conditioning:

a type of implicit memory for classical occasions

Rote rehearsal:

repetition, least effective

Chunking:

grouping info into meaningful units