unit 4 sensation and perception

11th ap psychology

sensation

process by which our sensory receptors and nervous system receive stimulus energies (information) from our environment

transduction

process of converting stimulus energy into neural activity (retina, cochlea, cilia)

adaptation

constant level of stimulus results in decreased response over time (impacts transduction)

perception

- process of selecting and identifying information from the environment

- organizing and interpreting sensory information so we can identify its meaning

bottom up processing

- using sensory receptors that works up to the brain's integration of sensory info

- ex: smelling popcorn, stubbing toe

top down processing

- using experience and expectations (higher-level mental processes) to process information

- ex: filling in gaps based on what we sense, green eggs and ham

psychophysics

study of the relationship between physical characteristics of stimuli and our psychological experience with them

human factors and engineering psychology

- use of scientific research to improve products

- goal: better understand what people expect and how people interact with products to create safer, more effective, and more reliable systems

- ex: cars, phones

absolute threshold

- the minimum stimulation needed to detect a stimulus 50% of the time

- ex: the least amount of basil one can taste in pasta

signal detection theory

- how and when we detect the presence of a faint stimulus in a background

- depends on person's experience, expectations, motivations, and level of fatigue

just noticeable difference

- the minimum difference between two stimuli required for detection 50% of the time

- ex: how much the volume have to increase/decrease before you can tell the music is louder/softer

weber's law

- two stimuli must differ by a constant proportion for the difference to be noticeable

- fixed ratio based on original stimulus

- ex: if you go from 1 to 2, then you must go from 2 to 4, then 3 to 6 to notice same difference

fechner's law

- continuous increase/decrease in physical energy will result in smaller increases in perceived magnitude

- not a true ratio

- eventually we reach a point where physical energy starts to level off and we no longer notice difference

- ex: concerts need a larger change to hear a difference

subliminal stimulation

stimuli below one's absolute threshold of conscious awareness (underlying messages)

cornea

- protects eye

- bends light towards central focal point to provide focus

pupil

- controls the amount of light that is able to enter the eye

- bright conditions: iris expands → pupil smaller

- dark conditions: iris contracts → pupil larger

lens

focuses image on back of the eye

retina

- converts light into electric impulses that are sent through the optic nerve

- transduction

- cones and rods

macula

large collection of photoreceptors that influence clarity in our visual processes

photoreceptors

cones and rods

fovea

- middle of macula

- bundle of cones

optic nerve

- sends visual information to the thalamus then the occipital lobes

- blind spot

cones

- 6 million

- center of retina (fovea)

- color sensitive

- clarity

rods

- 120 million

- edge of retina (periphery)

- night vision

feature detectors

- nerve cells that responds to shape, angle, and movement

- located in the visual cortex (brain cells)

parallel processing

the processing of several aspects of a stimulus simultaneously (color, depth, form, movement)

trichromatic theory

- hermann von helmholtz and thomas young

- retina contains 3 different color receptors

- can produce the perception of any color when stimulated in combination

dichromatic color vision

- individual lacks one of the 3 color receptors

- color blindness, usually the red or green receptor

opponent processing theory

- opposing retinal processes enable color vision

- red & green

- yellow & blue

- black & white

pinna

cartilage that channels sound waves into the external auditory canal

cochlea

converts stimulus from outside environment into nerve impulses for transmission to the brain (transduction)

tympanic membrane/eardrum

- conducts sound to the inner ear

- transmits vibrations to the ossicles (hammer, anvil, stirrup)

vestibular apparatus

maintains balance and has nothing to do with hearing

place theory

location in cochlea that is stimulated by pitch

frequency theory

how often a hair cell is stimulated

conduction hearing loss

- sound vibrations cannot be passed from the eardrum to cochlea due to damage in the middle ear

- ex: punctured or ruptured ear

sensorineural hearing loss

- also called nerve deafness

- caused by damage to the cochlea's receptor cells or to the auditory nerves

- cochlear implant

vestibular (somasthetic sense)

- tells us where our body is orientated in space (balance)

- located in the semicircular canals in ears

selective attention

the focusing of conscious awareness on a particular stimulus to the exclusion of others

cocktail party effect

- form of selective attention

- focus on a single talker among a mixture of conversations and background noises, ignoring other conversations

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

- form of inattentional blindness

- individuals don't notice a change after a brief visual interruption

change deafness

failure to notice a change in voice and/or speaking

choice blindness

- form of inattentional blindness

- people are "blind" to their own choices and preferences

visual capture

phenomena when vision competes with other senses, vision almost always win

figure-ground (gestalt principle)

the perceptual tendency to organize stimuli into objects that stand out from their surrounding

figure (gestalt principle)

- object stands out

- foreground

ground (gestalt principle)

- surrounding visual field

- background

visual (gestalt principle)

auditory (gestalt principle)

a singer (foreground) and their band (background)

gustatory (gestalt principle)

hotdog (background) with lots of onions (foreground)

olfactory (gestalt principle)

using a candle (foreground) to cover other smells (background)

grouping (gestalt principle)

perceptual tendency to organize stimuli into understandable groups

similarity (gestalt principle)

objects look similar to each other

proximity (gestalt principle)

how close objects are to each other

closure (gestalt principle)

filling in gaps

continuity (gestalt principle)

smooth, continuous patterns

depth perception

- the ability to see objects in 3 dimensions allowing us to judge distance, despite the fact that our retinas take in only 2 dimensions

- binocular cues

- monocular cues

visual cliffe

laboratory device for testing depth perception in infants and young animals

binocular cues

- retinal disparity

- convergence

- use of two eyes

retinal disparity

- comparing images from each eyes

- greater the difference = greater the object

- judges distance

convergence

- eyes turn inward as objects get nearer

- judges distance

monocular cues

- requires only one eye

- relative size

- relative height

- relative clarity

- relative motion

- interposition

- linear perspective

- light & shadow

- texture gradient

relative size

- using the perceived size of familiar object to determine depth/distance

- larger objects = closer

relative height

objects higher in our field of vision are farther away

relative clarity

hazy objects are farther away than sharp, clear objects

relation motion/motion parallax

- using a distant object to determine depth while in motion

- closer objects = faster

interposition

when one object partially blocks a view, we perceive it as closer

linear perspective

parallel lines appear to converge as they move farther into the distance

light and shadow

- nearby objects reflect more light

- dimmer objects = farther away

texture gradient

textured surfaces appear smoother and finer as distance increases

cilia

receptor cells that collect molecules of odor

olfactory bulb

- receives an electrical signal and generates a "code" that is sent to the brain for interpretation

- has sensory receptors part of the brain that influences memory

sensory interaction

- one sensory process influencing another

- ex: smell and taste; hold nose to lessen taste

papilla

bumps on the tongue's surface

taste buds

located in walls and grooves of the papilla, roof of mouth, and throat

tastes we can detect

- sweet

- sour

- salty

- bitter

- umami (savory/protein)

epidermis

waterproof, protective layer (melanin to protect from sun)

dermis

hair follicles, sweat glands, and touch receptors

hypodermis

fat and connective issues

mechanoreceptors

pressure, vibrations, texture

thermoreceptors

temperature of objects

nocireceptors

pain receptors

proprioceptors

position and movement (muscles, joints, tendons)

gate control theory

an area in the spinal cord that acts like a "gate" and either inhibit pain messages or transmit them to the brain

kinesthetic

- tells us where our body parts are in spatial/relational sense

- receptors located in muscle, joints, and tendons

stroboscopic motion

- illusion of motion by the rapid project of slightly changing images

- ex: film animations

phi phenomenon

- illusion of motion when fixed lights are turned on and off in a sequence

- ex: christmas lights

perceptual constancy

- understanding the object is not changing, even as the retinal image changes

- ex: a swinging door

size constancy

tendency to interpret object as always being the same size despite its distance

shape constancy

understanding that object's shape remains the same even though angle may change its shape on retina

light constancy

ability to see object as having constant level of lightness on matter how the lighting conditions change

perceptual adaptation

the ability to adjust to a new perception, but not perceived as the "new normal"

perceptual set

a mental predisposition to perceive one thing and not another that is based on experiences, assumptions, and expectations

parapsychology

- study of paranormal phenomena

- lacks replicable scientific evidence

- telepathy, clairvoyance, precognition

telepathy

mind to mind communication

clairvoyance

perceiving remote events

precognition

perceiving future events

nearsightedness

- eyeball too long

- image focused in front of the retina

- also called myopia

farsightedness

- eyeball too short, lens has incorrect curvature, cornea is flat

- image focused behind the retina

- also called hyperopia