Test your Awareness 1 (basketball game)

Core Concepts in Understanding Sensation and Perception

AP Unit 3

Reading pp108-117

I CAN

• Distinguish sensation vs. perception

• Apply Weber’s Law/Fetchner’s Law

• Apply transduction, adaptation and threshold to the senses

S and PS- the process by which we gain (sense)

information from the outside world

–occurs through receptor cells- specialized cells, which carry energy message to neuron

P- occurs after S; the way our brain mentally assigns meaning to the raw material we sensed- influenced by individual expectation

Core Concept (p111) Klingemanized• Our sense organs (ears, eyes, etc) are

the vehicle which transports stimuli from the world to our BRAIN. –Our BRAIN does the sensing

•So, what we see, hear, etc… is our brains NEURAL REPRESENTATION of what actually exists–Color blindness, deafness, etc

All Senses share these 3 Characteristics1. Transduction- ability to convert physical

energy (ex: sound waves) into a neural transmission

1. Once stimulated nerve impulses travel along sensory pathways to processing area of cortex

2. Adaptation- responsiveness to sensations lessens over time (thalamus stops ranking it as important)

3. Thresholds- study of is called psychophysics; determined by the least amount of energy you can detect at least ½ the time

Absolute Thresholds

• Taste: 1 gram (.0356 ounce) of table salt in 500 liters (529 quarts) of water

• Smell: 1 drop of perfume diffused throughout a three-room apartment

• Touch: the wing of a bee falling on your cheek from a height of 1cm (.39 inch)

• Hearing: the tick of a watch from 6 meters (20 feet) in very quiet conditions

• Vision: a candle flame seen from 50km (30 miles) on a clear, dark night

Stimulation Transduction Sensation Perception

Difference Threshold/ Just Noticeable Difference

• What is the smallest difference in stimuli, where you can notice a difference- (think TV volume)

Difference ThresholdDifference Threshold: Minimum difference

between two stimuli required for detection 50% of the time, also called

just noticeable difference (JND).DifferenceThreshold

Tell when you (observer) detect a difference in the light.

No

Observer’s Response

No Yes

Weber’s Law• Change in intensity of stimulus=constant

• Applied: Bob lifts 10 lb weights and his JND is 2 additional lbs. If Bob lifts 100 lbs, his JND is going to be 20 lbs

–This means the JND is large(takes more difference) when the stimulus intensity is high and small (takes little difference) when intensity is low• Book Experiment

EX: Bob’s jnd when initially carrying 10 pounds is 1 pound. Weber’s law states that if Bob was carrying 100 pounds initially, his jnd will be 10 pounds.

Fechner’s Law and Steven’s Law• Deal with real and perceived magnitude of

stimulus

• Say the same thing, but Steven’s accounts for more senses- pain and temperature

– EX: Susie is listening to the radio, when she 1st turns it on, she adjusts the volume a little and it make a BIG difference.

• After listening for a while, she changes the volume by the same degree, but barely notices a difference.

Signal Detection Theory (SDT)Predicts how and when we detect the

presence of a faint stimulus (signal) amid background noise (other stimulation). SDT assumes that there is no single

absolute threshold and detection depends on:Person’s

experienceExpectationsMotivationLevel of fatigue

Carol L

ee/ Tony Stone Im

agesFight Club- our detection of “clips” the 1st time we see it is far LESS then subsequent viewingsImplication: we can “turn up or down” our ability to detect the presence of stimuli

No

Detection

Intensity

AbsoluteThreshold

Detected

YesYesNo No

Observer’s Response

Tell when you (the observer) detect the light.

Test your Awareness 2

Subliminal Messages

• Subliminal- below the threshold–Subliminal Priming- shown/told (good

EX on p117)• No proof that this can influence a mass

audience or that tapes played while sleep can make you quit smoking; however, evidence indicates a positive correlation between exposure to SM and achieving desired outcome

Friends: Quit Smoking

Can I?

• Distinguish sensation vs. perception

• Apply Weber’s Law/Fetchner’s Law

• Apply transduction, adaptation and threshold to the senses