General Psychology Chapter 3 Sensation and Perception Chapter 3 Sensation and Perception.
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SENSATION AND
PERCEPTION
Sensation and Perception
I. Detecting, Processing and Interpreting Experiences
II. Sensory ReceptorsIII. Sensory ThresholdsIV. Habituation and Sensory
AdaptationV. The Sensory OrgansVI. Perceiving Sensory Stimuli
SENSATIONthe process of receiving stimulus energies from the external environment
- sensory organs: eyes (visual system)ears (auditory)nose (olfactory)tongue (gustatory)skin (tactile)
PERCEPTION
the process of organizing and interpreting sensory information to give it meaning.
Prior experiencesExpectationsMemoryBiases
Why is it important to study sensation and perception?
The purpose of perception is:1) to represent information from the
outside world internally;2) adaptation that improves a species’
chances for survival; and3) to help in designing devices to
restore perception to those who have lost some (or all) and also to devise treatments for other perceptual problems.
Have you ever experienced (or seen someone) bumping
into a clear window glass because you did not know
that it was there?
BOTTOM-UP PROCESSING
TOP-DOWN PROCESSING
- Sensory receptors register information about the external environment and send it up to the brain for analysis and interpretation.
- Starts out with cognitive processing at the higher levels of the brain.
- Cognitive processes include knowledge, beliefs and expectations.
JIGSAW PUZZLE
SENSORY RECEPTORSAll sensation begins with sensory
receptors.Sensory receptors are
specialized cells that detect and transmit stimulus information to sensory nerves and the brain.
SENSORY THRESHOLDSBuzzing mosquito?Difference between regular Coke
and Coke Zero?
SENSORY THRESHOLDS
Absolute threshold
Difference threshold
- Minimum amount of energy that a person can detect
- just noticeable difference (jnd)- the degree of difference that must
exist between two stimuli before the difference is detected.
SENSORY THRESHOLDSAbsolute Threshold- Orange juice- One tablespoon?- Two tablespoon?- Three tablespoon!
- Watching TV while your roommate is sleeping.
- Volume?
-
2 4 6 9 12
13
Approximate Absolute Thresholds
Vision- A candle flame at 30 miles on a dark, clear night.Hearing- A ticking watch at 20 feet under quiet conditions.Smell- One drop of perfume diffused throughout 3 roomsTaste- A teaspoon of sugar in 2 gallons of waterTouch- The wing of a fly falling on your cheek from a
distance of one centimeter.
Difference Threshold- Watching TV while your
roommate is sleeping.- Your roommate, suddenly wakes-
up.- Also wants to watch the TV!- Volume?
-
2 4 6 9 12
13
No JND!
JND!
A student late for his class.10: 03 – late?10:05 – late?10: 10 – late?10:15 – late!!!It takes 15 minutes for a student to
be detected as late.Absolute or difference
threshold?*Depends on the individual who
perceives and the condition of the environment.
Subliminal Perception- the ability to detect information
below the level of conscious awareness.
- JAMES VICARY (1957)- “Eat Popcorn”; “Drink Coke”- .003 second once every 5 secs.- The sales of popcorn and coke
increased!- HOAX!- Subliminal perception does not
work in advertising.
HABITUATION AND SENSORY ADAPTATION
The lower centers of the brain sort through sensory stimulation and “ignore” or prevent conscious attention to stimuli that do not change.
Sound of airconSmell of garbageReading your readings?
Sensory adaptation- The sensory receptor cells become
less responsive to an unchanging stimulus.
- The receptors are no longer sending signals to the brain.
Habituation- The sensory receptor cells are still
responding to the stimulus, but the lower centers of the brain are not sending the signals from those receptors in the cortex.
QUESTIONS?