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Psychology 101Psychology 101

SensationSensation

Sensation Sensation vsvs PerceptionPerception

•• WhatWhat’’s the difference?s the difference?

Sensation Sensation vsvs PerceptionPerception

•• SensationSensation

–– What comes into our body through our What comes into our body through our

sensory organssensory organs

•• PerceptionPerception

–– What our brain does with that informationWhat our brain does with that information

How do we construct our How do we construct our

environment?environment?

•• We We constructconstruct itit

•• Our systems can be tricked!Our systems can be tricked!

MullerMuller--LyerLyer TitchenerTitchener’’ss circlescircles

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Red spiralsRed spiralsLook at the Look at the greysgreys

KaniszaKanisza’’ss triangletriangle

An introduction to the Gestalt principles

How can we study our senses?How can we study our senses?

•• What can we do to understand how visual What can we do to understand how visual

information is processed?information is processed?

–– Sounds?Sounds?

–– Smells?Smells?

•• How could we study this in psychology?How could we study this in psychology?

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PsychophysicsPsychophysics

•• The main ideaThe main idea

•• We notice some incoming information and We notice some incoming information and

dondon’’t process otherst process others

•• Absolute thresholdsAbsolute thresholds

–– Minimum threshold to detect something 50% Minimum threshold to detect something 50%

of the timeof the time

Psychophysics: The pointPsychophysics: The point

•• To learn about our senses by pushing To learn about our senses by pushing

them to the limitsthem to the limits

•• Example: the auditory systemExample: the auditory system

–– Play a sound very quietlyPlay a sound very quietly

–– Eventually itEventually it’’ll be so quiet, you may not be ll be so quiet, you may not be

able to hear itable to hear it

–– Absolute threshold: the loudness that people Absolute threshold: the loudness that people

say they can hear the sound 50% of the timesay they can hear the sound 50% of the time

Signal Detection TheorySignal Detection TheoryOther things: Subliminal Other things: Subliminal

StimulationStimulation

•• Stimulating our Stimulating our

consciousnessconsciousness

•• Priming studiesPriming studies

–– Changing opinions by Changing opinions by

showing something showing something

subliminallysubliminally

–– Ch_ _ _Ch_ _ _

Just Noticeable DifferenceJust Noticeable Difference

•• WeberWeber’’s laws law

–– Difference thresholds are Difference thresholds are

not constant, but not constant, but

proportionalproportional

–– Start with a 1lb bookStart with a 1lb book

•• May notice a .1 lb changeMay notice a .1 lb change

–– Now start with a 1000 lb Now start with a 1000 lb

deskdesk

••Will you notice a .1 lb Will you notice a .1 lb

change?change?

Just Noticeable DifferenceJust Noticeable Difference

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Sensory adaptationSensory adaptation

•• Do you feel your clothes if they are still?Do you feel your clothes if they are still?

•• How about hearing a sound that hums in How about hearing a sound that hums in

the background consistently?the background consistently?

What about vision?What about vision?

•• What about a line that is in one place in What about a line that is in one place in

your field of vision?your field of vision?

–– Why is this different?Why is this different?

–– Eyes are constantly movingEyes are constantly moving

•• SaccadesSaccades

Two ways to processing the worldTwo ways to processing the world

•• BottomBottom--up processing:up processing:–– Our sensory systems experience the world Our sensory systems experience the world and send the information upwards to the and send the information upwards to the brainbrain•• EgEg. watching a movie. watching a movie

•• TopTop--down processingdown processing–– How our minds interpret what our senses How our minds interpret what our senses detect (detect (ieie. seeing, hearing). seeing, hearing)•• EgEg. Don. Don’’t look behind the doort look behind the door

Vision: The beginningVision: The beginning

•• What do we see?What do we see?

–– Light is wavesLight is waves

The visual spectrumThe visual spectrum

•• We can only see a small portion of the We can only see a small portion of the

waves of visual lightwaves of visual light

VisionVision

•• The EyeballThe Eyeball

•• Light shines through Light shines through

the corneathe cornea

•• Becomes inverted on Becomes inverted on

the retinathe retina

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Parts of the eyeballParts of the eyeball

•• Cornea: outermost partCornea: outermost part

–– Protects the eyeProtects the eye

•• Pupil and IrisPupil and Iris

–– Allow light to enterAllow light to enter

•• LensLens

–– Focus light on retinaFocus light on retina

•• RetinaRetina

–– Back of eyeball where light is processedBack of eyeball where light is processed

The Retina: The most important The Retina: The most important

partpart

•• Contains rods and conesContains rods and cones

•• Rods: nighttime use Rods: nighttime use –– insensitive to colorinsensitive to color

–– located in retinal periphery located in retinal periphery

–– When you step into a movie theatre, it takes a while When you step into a movie theatre, it takes a while to see because your rods are kicking in.to see because your rods are kicking in.

•• Cones: 3 types of light sensitivity (red, green, Cones: 3 types of light sensitivity (red, green, blue) blue) –– essential for color perception essential for color perception

–– daytime use daytime use

–– primarily in center of retinaprimarily in center of retina•• better acuitybetter acuity

Rods and ConesRods and Cones•• They are sensitive to different They are sensitive to different

wavelengthswavelengths

What do rods and cones do?What do rods and cones do?

•• TransductionTransduction

–– Turns light into something our nervous Turns light into something our nervous

system can usesystem can use

•• Electrical signalElectrical signal

–– Rods and Cones do this specifically for their Rods and Cones do this specifically for their

type (color) of lighttype (color) of light

What about problems seeing?What about problems seeing?

•• Nearsightedness: image focused too soonNearsightedness: image focused too soon

•• Farsightedness: image focused too farFarsightedness: image focused too far

How the visual system worksHow the visual system works

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Stages to visual processingStages to visual processing

•• Visual perception occurs in stagesVisual perception occurs in stages

•• One are may process colorOne are may process color

•• Another may process depth or formAnother may process depth or form

Color visionColor vision

•• YoungYoung--HelmholtzHelmholtz theorytheory

–– TrichromacyTrichromacy

–– Found in the retinaFound in the retina

•• Opponent process theoryOpponent process theory

–– RedRed--green, bluegreen, blue--yellow, and blackyellow, and black--whitewhite

–– Input from one color inhibits the other colorInput from one color inhibits the other color

YoungYoung--HelmholtzHelmholtz TheoryTheory Opponent Process TheoryOpponent Process Theory

HearingHearing

•• Sounds are wavesSounds are waves

•• Amplitude / Height = loudnessAmplitude / Height = loudness

•• Frequency = pitchFrequency = pitch

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The EarThe Ear

•• Outer earOuter ear–– Ends at ear drumEnds at ear drum

•• Middle earMiddle ear–– Composed of bonesComposed of bones

•• Inner earInner ear–– CochleaCochlea

–– Fluid filledFluid filled

–– HairsHairs•• TransductionTransduction

Typical SoundsTypical Sounds

How we hearHow we hear

•• Sound waves get to Sound waves get to the cochleathe cochlea

•• Ripples in fluidRipples in fluid

•• Hair cells sway with Hair cells sway with the ripplesthe ripples

•• Different frequencies Different frequencies of sound move the of sound move the hair cells that are in hair cells that are in different parts of the different parts of the cochleacochlea

Getting to the BrainGetting to the Brain

•• Different parts of the auditory cortex Different parts of the auditory cortex

process the different frequencies of soundprocess the different frequencies of sound

Higher frequencies processed in the yellow regionLower frequencies processed in the blue region

Sound Location ProcessingSound Location Processing

•• How can we tell where a sound is coming How can we tell where a sound is coming

from?from?

–– Difference in loudness between the two earsDifference in loudness between the two ears

•• InterauralInteraural Intensity DifferenceIntensity Difference

–– Difference in time of arrival for the sound Difference in time of arrival for the sound

waves between the two earswaves between the two ears

•• InterauralInteraural Time DifferenceTime Difference

Touch processingTouch processing

••Multiple Multiple somatosensorysomatosensory

subsystemssubsystems

––TouchTouch

••Pressure, vibrationPressure, vibration

••TemperatureTemperature

••PainPain

–– Joint positionJoint position

––Muscle stretchMuscle stretch

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Organization in the BrainOrganization in the Brain TasteTaste

�� Taste buds: sensory receptorsTaste buds: sensory receptors

�� Taste SensationsTaste Sensations�� sweetsweet

�� soursour

�� saltysalty

�� bitterbitter

�� Sensory InteractionSensory Interaction�� the principle that one sense may influence anotherthe principle that one sense may influence another

�� as when the smell of food influences its tasteas when the smell of food influences its taste

The TongueThe Tongue