Sensation &

Perception

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 senses.

Sensation is a bottom-up process;Perception is a top-down process.

http://honolulu.hawaii.edu/distance/sci122/Programs/p3/vase&bach.html

Video…

“Lights, Camera, Magic!”

ThresholdsThresholds• Absolute ThresholdAbsolute Threshold – when a stimulus is – when a stimulus is

detectable 50% of the time; minimum detectable 50% of the time; minimum stimulation to detect a particular stimulus.stimulation to detect a particular stimulus.

• SubliminalSubliminal – stimuli that are below – stimuli that are below threshold; can only influence you in the threshold; can only influence you in the short term and superficially.short term and superficially.

• Just Noticeable DifferenceJust Noticeable Difference – the minimum – the minimum difference a person can tell between two difference a person can tell between two things 50% of the time.things 50% of the time.

• Sensory AdaptationSensory Adaptation – occurs when – occurs when stimulus doesn’t change, so our sensitivity stimulus doesn’t change, so our sensitivity diminishes.diminishes.

VisionVision

P. 148

VisionVision

P. 149

Visual ActivitiesVisual Activities

• Blind Spot:Blind Spot:– Close one eye, extend index finger, and Close one eye, extend index finger, and

move hand around ‘til it disappears.move hand around ‘til it disappears.

• Hole in hand:Hole in hand:– Roll up piece of paper, and put in front Roll up piece of paper, and put in front

of one eye; hold your flattened hand in of one eye; hold your flattened hand in front of the other.front of the other.

Visual FieldsVisual Fields

• Left and Right Visual Left and Right Visual Fields – each eye has Fields – each eye has both, they overlap, both, they overlap, and give us 3-D Vision.and give us 3-D Vision.

• www.eyetec.netwww.eyetec.net/ group3/M11S1.htm/ group3/M11S1.htm

Another Movie!Another Movie!

““Perception: Inverted Vision”Perception: Inverted Vision”

Color VisionColor Vision

• Three color theory – Cones are sensitive to three Three color theory – Cones are sensitive to three wavelengths of light: red, blue, green.wavelengths of light: red, blue, green.

• Opponent process – your brain adds yellow into Opponent process – your brain adds yellow into the picture…the picture…

• Context effects – the whites of your eyes look Context effects – the whites of your eyes look whiter when you wear blue, but look yellow whey whiter when you wear blue, but look yellow whey you wear yellow (P. 155).you wear yellow (P. 155).

• Color Constancy – you see a tomato as red Color Constancy – you see a tomato as red regardless of the context (P. 155).regardless of the context (P. 155).

• Wavelength = hue; Amplitude = Wavelength = hue; Amplitude = brightness/intensity (P. 147).brightness/intensity (P. 147).

HearingHearing

►Stimulus: sound wavesStimulus: sound waves►Damaged when sound >85 decibels.Damaged when sound >85 decibels.►Stereo-audition.Stereo-audition.►Amplitude = loudness;Amplitude = loudness;

frequency = pitchfrequency = pitch►Activity – find a partner…Activity – find a partner…

Locate sound.Locate sound.

HearingHearing P. 157

TouchTouch

Four sensations:Four sensations: Pressure, warmth, cold, and painPressure, warmth, cold, and pain

Gate Control TheoryGate Control Theory – only one – only one sensation at a time: pain travels on sensation at a time: pain travels on smaller fibers, other sensations on smaller fibers, other sensations on larger fibers – action in large fibers larger fibers – action in large fibers blocks action in the small.blocks action in the small.

Good Pain? Tells you when something Good Pain? Tells you when something is wrong.is wrong.

PainPain

Some people born with reduced Some people born with reduced ability to feel pain – cannot detect ability to feel pain – cannot detect hunger, broken bones, fever…hunger, broken bones, fever…

Blocking Pain:Blocking Pain: Mind over matter (meditation, Lamaze)Mind over matter (meditation, Lamaze) Acupuncture and counterstimulationAcupuncture and counterstimulation Medication (blocks pain transmission)Medication (blocks pain transmission) Endorphins (Endogenous Morphine)Endorphins (Endogenous Morphine)

Other TactileOther Tactile

KinesthesisKinesthesis – knowing where our – knowing where our body parts are: visually cued; body parts are: visually cued; knowing how to get where we want knowing how to get where we want to be/do what we want.to be/do what we want.

Vestibular SenseVestibular Sense – monitors body – monitors body movements and balance: based in movements and balance: based in semicircular canals in ear.semicircular canals in ear.

SmellSmell

Very basic; primitive sense close to brainVery basic; primitive sense close to brain Pheromones??Pheromones?? Smells connected to memory, and are Smells connected to memory, and are

powerful.powerful. Smell based on chemical processes; Smell based on chemical processes;

sniffing circulates more air through nose.sniffing circulates more air through nose.

Taste

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”.

ReferencesReferences

http://honolulu.hawaii.edu/distance/sci122/Prograhttp://honolulu.hawaii.edu/distance/sci122/Programs/p3/vase&bach.htmlms/p3/vase&bach.html

Myers, D. (2005). Myers, D. (2005). Exploring PsychologyExploring Psychology (6 (6thth ed.). ed.). New York: Worth Publishers.New York: Worth Publishers.

Myers, D. (2005). Myers, D. (2005). Instructor’s Resource CD-ROM: Instructor’s Resource CD-ROM: To Accompany David G. Myers Exploring To Accompany David G. Myers Exploring Psychology, 6Psychology, 6thth ed. ed. [Computer Software]. New [Computer Software]. New York: Worth Publishers.York: Worth Publishers. CH05_illustration (D:\PowerPoints\Illustration PPTs)CH05_illustration (D:\PowerPoints\Illustration PPTs) Ch5 (D:\PowerPoints\Lecture PPTs)Ch5 (D:\PowerPoints\Lecture PPTs)

www.eyetec.net/ group3/M11S1.htm www.wesleyan.edu/wesmaps

/ course0304/psyc222s.htm