Sensation vs Perception
Sensation – detecting physical energy
from the environment and encoding it
as neural signals.
Perception – the process of selecting,
organizing and interpreting our
Sensation is a bottom-up process;
Perception is a top-down process.
“Lights, Camera, Magic!”
• Absolute Threshold – when a stimulus is
detectable 50% of the time; minimum
stimulation to detect a particular stimulus.
• Subliminal – stimuli that are below threshold;
can only influence you in the short term and
• Just Noticeable Difference – the minimum
difference a person can tell between two things
50% of the time.
• Sensory Adaptation – occurs when stimulus
doesn‟t change, so our sensitivity diminishes.
• Blind Spot:
– Close one eye, extend index finger, and move
hand around „til it disappears.
• Hole in hand:
– Roll up piece of paper, and put in front of one
eye; hold your flattened hand in front of the
• Left and Right Visual
Fields – each eye has
both, they overlap, and
give us 3-D Vision.
“Perception: Inverted Vision”
• Three color theory – Cones are sensitive to three
wavelengths of light: red, blue, green.
• Opponent process – your brain adds yellow into the
• Context effects – the whites of your eyes look whiter
when you wear blue, but look yellow whey you wear
yellow (P. 155).
• Color Constancy – you see a tomato as red regardless of
the context (P. 155).
• Wavelength = hue; Amplitude = brightness/intensity (P.
► Stimulus: sound waves
► Damaged when sound >85 decibels.
► Amplitude = loudness;
frequency = pitch
► Activity – find a partner…
Hearing P. 157
Pressure, warmth, cold, and pain
Gate Control Theory – only one sensation
at a time: pain travels on smaller fibers,
other sensations on larger fibers – action
in large fibers blocks action in the small.
Good Pain? Tells you when something is
Some people born with reduced ability to
feel pain – cannot detect hunger, broken
Mind over matter (meditation, Lamaze)
Acupuncture and counterstimulation
Medication (blocks pain transmission)
Endorphins (Endogenous Morphine)
Kinesthesis – knowing where our body
parts are: visually cued; knowing how to
get where we want to be/do what we
Vestibular Sense – monitors body
movements and balance: based in
semicircular canals in ear.
Very basic; primitive sense close to brain
Smells connected to memory, and are
Smell based on chemical processes;
sniffing circulates more air through nose.
Sweet, sour, salty, bitter
Flavor = smell + taste
>200 taste buds that each respond to
chemicals in food.
Taste diminishes with age, smoking,
and alcohol use.
Movie: “Tasters and Supertasters”.
Myers, D. (2005). Exploring Psychology (6th ed.). New
York: Worth Publishers.
Myers, D. (2005). Instructor‟s Resource CD-ROM: To
Accompany David G. Myers Exploring Psychology, 6th ed.
[Computer Software]. New York: Worth Publishers.
CH05_illustration (D:\PowerPoints\Illustration PPTs)
Ch5 (D:\PowerPoints\Lecture PPTs)