7 sensation

8/14/2019 7 Sensation

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SensationSensation

Sensation is the process by which ourSensation is the process by which our

sensory receptors and nervous systemsensory receptors and nervous system

receive and represent stimulus energiesreceive and represent stimulus energies

from our environmentfrom our environment

Perception The process of organizingPerception The process of organizing

and interpreting information, enabling usand interpreting information, enabling us

to recognize meaningful objects andto recognize meaningful objects andeventsevents


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Information ProcessingInformation Processing

Bottom up Processing analysis thatBottom up Processing analysis that

begins with the senses and ends in thebegins with the senses and ends in the

brainbrain

Top Down Processing informationTop Down Processing information

processing guided by higher level mentalprocessing guided by higher level mental

processes, influenced by expectations andprocesses, influenced by expectations and

experienceexperience


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ThresholdsThresholds

Psychophysics study of how energyPsychophysics study of how energy(stimuli) affects psychology.(stimuli) affects psychology.

Absolute Threshold The minimumAbsolute Threshold The minimum

stimulation needed to detect a particularstimulation needed to detect a particularstimulus at least 50% of the time.stimulus at least 50% of the time.

Single Detection Theory Theory thatSingle Detection Theory Theory that

there is no static absolute threshold butthere is no static absolute threshold butthat it changes depending on a personsthat it changes depending on a personsexperience, expectations, fatigue level, etcexperience, expectations, fatigue level, etc


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Subliminal MessagesSubliminal Messages

Subliminal stimuli below the absoluteSubliminal stimuli below the absolute

threshold. Studies show that subliminal stimulithreshold. Studies show that subliminal stimuli

may still have some affect on our thinking ormay still have some affect on our thinking or

dispositions.dispositions.Subliminal stimuli still register in ourSubliminal stimuli still register in our

subconscious and can affect general moods orsubconscious and can affect general moods or

prepare us to process some information fasterprepare us to process some information faster

but it cannot be used to give detailedbut it cannot be used to give detailed

suggestions that we are unaware of.suggestions that we are unaware of.


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Difference ThresholdsDifference Thresholds

Difference thresholds the minimumDifference thresholds the minimum

difference you can detect between anydifference you can detect between any

two stimuli at least 50% of the time.two stimuli at least 50% of the time.

Webers law states that the differenceWebers law states that the difference

threshold is determined by % differencethreshold is determined by % difference

change, not a constant amount.change, not a constant amount.


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Sensory AdaptationSensory Adaptation

Sensory adaptation is the diminishingSensory adaptation is the diminishing

sensitivity of a stimulus as a consequencesensitivity of a stimulus as a consequence

of constant stimulation.of constant stimulation.

Transduction the changing of stimulusTransduction the changing of stimulus

energies into electrical impulses for ourenergies into electrical impulses for our

nervous system.nervous system.


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The EyeThe Eye

The Stimulus LIGHT!The Stimulus LIGHT!

Light is actually a part of something calledLight is actually a part of something calledelectromagnetic radiation (energy).electromagnetic radiation (energy).

Electromagnetic energy is measured in waves,Electromagnetic energy is measured in waves,Some basic wave properties are wavelengthSome basic wave properties are wavelengthand Amplitudeand Amplitude


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Wave PropertiesWave Properties

For light, the wavelength determines theFor light, the wavelength determines the

color or hue. The amplitude determinescolor or hue. The amplitude determines

the brightness or strength.the brightness or strength.

For sound, the wavelength is the pitch andFor sound, the wavelength is the pitch and

the amplitude is the volume.the amplitude is the volume.


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The EyeThe Eye


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AcuityAcuity

People who have trouble seeing usually havePeople who have trouble seeing usually have

problems withproblems with AcuityAcuity..

TheThe corneacornea and theand the lenslens are supposed to focusare supposed to focus

light directly on the retina, if they dont and thelight directly on the retina, if they dont and theimage is focused before theimage is focused before the retinaretina you areyou are

nearsightednearsighted, if the image is focused behind the, if the image is focused behind the

retina you areretina you are farsightedfarsighted. Glasses or contacts. Glasses or contacts

simply bend the light so it focuses in the rightsimply bend the light so it focuses in the right

place.place.


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The RetinaThe Retina

The back of the eye is called the Retina this isThe back of the eye is called the Retina this is

where transduction occurs.where transduction occurs.

There are many special cells that work together.There are many special cells that work together.

Rods are light detection cells that detect lowRods are light detection cells that detect lowlevels of light in black and whitelevels of light in black and white

Cones are detection cells that are better atCones are detection cells that are better at

detecting detail and can detect color, mostdetecting detail and can detect color, mostcones are located in the fovea, the center of thecones are located in the fovea, the center of the

retina where most of the light reaches.retina where most of the light reaches.


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The RetinaThe Retina

Bipolar cells send messages from cones andBipolar cells send messages from cones and

rods to Gaglion cells. Many times several rodsrods to Gaglion cells. Many times several rods

are connected to a bipolar cell, whereasare connected to a bipolar cell, whereas

sometime a single cone with be connected tosometime a single cone with be connected toanother. This means that rods help us see atanother. This means that rods help us see at

night more, but cones can reveal more detail.night more, but cones can reveal more detail.

Ganglion cells axons form the Optic Nerve andGanglion cells axons form the Optic Nerve and

carry the sum of information of the 130 millioncarry the sum of information of the 130 million

rod and cone receptors to the brain.rod and cone receptors to the brain.


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Visual ProcessingVisual Processing

Feature Detection The brain processesFeature Detection The brain processes

visual information in pieces. There arevisual information in pieces. There are

parts of the visual cortex that respond toparts of the visual cortex that respond to

specific stimuli such as movement, a linespecific stimuli such as movement, a line

drawn at a particular angle, color, curves,drawn at a particular angle, color, curves,

depth perception, etc. All of thesedepth perception, etc. All of these

features together form a picture for yourfeatures together form a picture for yourmind.mind.


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Parallel ProcessingParallel Processing

The brain processes millions of signals atThe brain processes millions of signals at

the same time combining all thethe same time combining all the

information to form a complete idea,information to form a complete idea,

thought or picture in your mind.thought or picture in your mind.


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Color VisionColor Vision

The human eye can discriminate between over 7The human eye can discriminate between over 7

million colorsmillion colors

Young-Helmholtz trichromatic theory State thatYoung-Helmholtz trichromatic theory State that

the retina has three types of color receptorsthe retina has three types of color receptorseach specially sensitive to one of the threeeach specially sensitive to one of the three

primary colors: red, green, or blue.primary colors: red, green, or blue.

Most color deficient people are not totally colorMost color deficient people are not totally color

blind, they lack red or green functioning conesblind, they lack red or green functioning cones

so they have trouble distinguishing between redso they have trouble distinguishing between red

and green.and green.


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Color VisionColor Vision

Color processing occurs in two stages.Color processing occurs in two stages.

First the retina reads red, green, or blueFirst the retina reads red, green, or blue

However as the signal is sent to the brainHowever as the signal is sent to the brainit goes through another process.it goes through another process.

The opponent process theory states thatThe opponent process theory states thatsome neurons be excited when theysome neurons be excited when they

detect red but inhibited with green, or thedetect red but inhibited with green, or theopposite. This also happens for blue andopposite. This also happens for blue andyellow, and black and white.yellow, and black and white.


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Color visionColor vision

This means that you cannot detect both colors atThis means that you cannot detect both colors at

once, so you will never see a greenish red butonce, so you will never see a greenish red but

instead you perceive yellow.instead you perceive yellow.

Color Constancy The other important factorColor Constancy The other important factorregarding color vision is that your perception ofregarding color vision is that your perception of

color depends not only on the wavelengthscolor depends not only on the wavelengths

detected in your retina but your brainsdetected in your retina but your brains

processing of it in theprocessing of it in the contextcontext of other colors orof other colors orenvironment this is especially important forenvironment this is especially important for

things like art, fashion, interior decoration etc.things like art, fashion, interior decoration etc.


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The EarThe Ear


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TransductionTransduction

Transduction occurs in theTransduction occurs in the CochleaCochlea in thein the

inner ear. The Cochlea is lined with up toinner ear. The Cochlea is lined with up to

16000 little hair cells that stand in fluid. As16000 little hair cells that stand in fluid. As

the sound waves are conducted to thethe sound waves are conducted to theCochlea the hairs move back and forth toCochlea the hairs move back and forth to

the vibrations and their movement triggersthe vibrations and their movement triggers

electrical neural impulses.electrical neural impulses.


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How do we perceive Pitch?How do we perceive Pitch?

There are multiple theories on how weThere are multiple theories on how wenotice pitch.notice pitch.

Place theory states that you determinePlace theory states that you determine

pitch based on where on the cochleaspitch based on where on the cochleasmembrane the hair cells are stimulated.membrane the hair cells are stimulated.

Frequency theory states that the hair cellsFrequency theory states that the hair cells

vibrate with the same frequency of thevibrate with the same frequency of thesound wave and your brain can tell pitchsound wave and your brain can tell pitchby the frequency of neural signals sent.by the frequency of neural signals sent.


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How do we perceive Pitch?How do we perceive Pitch?

Both theories do not completely explainBoth theories do not completely explainhow we hear pitch. Neurons can only firehow we hear pitch. Neurons can only fireupto 1000 times a second, yet we canupto 1000 times a second, yet we can

hear at frequencies much higher than that.hear at frequencies much higher than that.Place theory also does not explain howPlace theory also does not explain howwe hear low frequency sounds becausewe hear low frequency sounds becauseneuron firing is not localized to one areaneuron firing is not localized to one area

when low frequency sounds are heard.when low frequency sounds are heard.Thus place theory is good for high pitchThus place theory is good for high pitchand frequency theory explains low pitch.and frequency theory explains low pitch.


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Locating soundsLocating sounds

You brain can tell which direction sound isYou brain can tell which direction sound is

coming from by which hear hears thecoming from by which hear hears the

sound first, as well as the differences insound first, as well as the differences in

volume from one ear to the next.volume from one ear to the next.


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Hearing LossHearing Loss

Conduction Hearing Loss hearing lossConduction Hearing Loss hearing loss

that occurs when the mechanical processthat occurs when the mechanical process

of conducting soundwaves from the earof conducting soundwaves from the ear

drum to the cochlea is disrupted (fordrum to the cochlea is disrupted (forexample a punctured ear drum.)example a punctured ear drum.)

Sensorineural hearing loss hearing lossSensorineural hearing loss hearing loss

due to the damage of the cochleasdue to the damage of the cochleashaircells. (cannot be repaired)haircells. (cannot be repaired)


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TouchTouch

The skin has four distinct sensesThe skin has four distinct senses

PressurePressure

WarmthWarmthColdCold

PainPain


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What is Pain?What is Pain?

Pain is dependant onPain is dependant onboth the physicalboth the physicalsensation of it, the regionsensation of it, the regionthat it comes from and thethat it comes from and the

Brain interpreting it.Brain interpreting it.7 out of 10 Amputees7 out of 10 Amputeesreport feeling pain in theirreport feeling pain in theirmissing limbs so pain ismissing limbs so pain is

partially controlled by thepartially controlled by themind.mind.

There are no particularThere are no particularpain receptors.pain receptors.


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Gate Control TheoryGate Control Theory

Gate control theory explains some aspectsGate control theory explains some aspectsof pain. According to this theory painof pain. According to this theory painmessages travel to the spinal cord inmessages travel to the spinal cord in

smaller nerve fibers which are turned off ifsmaller nerve fibers which are turned off ifthere are also signals coming from largerthere are also signals coming from largernerve fibers or can be turned off bynerve fibers or can be turned off bymessages coming from the brain. Thus ifmessages coming from the brain. Thus if

you stub your toe, you rub the area aroundyou stub your toe, you rub the area aroundit to stimulate the larger fibers and try andit to stimulate the larger fibers and try andturn some of the pain messages off.turn some of the pain messages off.


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Psychology of PainPsychology of Pain

Seeing other people in pain often makes youSeeing other people in pain often makes youmore aware of your own pain. People feel moremore aware of your own pain. People feel morepain when they see others suffer.pain when they see others suffer.

People remember the worst parts of pain, butPeople remember the worst parts of pain, but

not the length of time in pain.not the length of time in pain.Pain control Options include drugs (endorphinPain control Options include drugs (endorphinaffecting opiates) surgery, acupuncture,affecting opiates) surgery, acupuncture,electrical stimulation, massage, exercise,electrical stimulation, massage, exercise,

hypnosis, relaxation training, and thoughthypnosis, relaxation training, and thoughtdistraction. Example: Lamaze techniques use,distraction. Example: Lamaze techniques use,counterdistraction (massage), thoughtcounterdistraction (massage), thoughtdistraction, and relaxation techniques.distraction, and relaxation techniques.


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TasteTaste

Taste, like touch has fourTaste, like touch has fourbasic sensationsbasic sensations

SourSour

BitterBitter

SweetSweet

SaltySalty


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TasteTaste

Taste is a chemical senseTaste is a chemical sense

Inside each bump on the top and sides of yourInside each bump on the top and sides of yourtongue are 200 or more taste buds.tongue are 200 or more taste buds.

These taste buds trap food chemicals in a poreThese taste buds trap food chemicals in a porethat are then sensed by 50 to 100 taste cells thatthat are then sensed by 50 to 100 taste cells thatproject hair-like receptors into the pore.project hair-like receptors into the pore.

Taste receptors grow back every two weeks orTaste receptors grow back every two weeks orso, so if your burn them accidentally you wontso, so if your burn them accidentally you wont

have permanent taste loss.have permanent taste loss.However, as you grow older the number of tasteHowever, as you grow older the number of tastebuds decreases, so often adults like morebuds decreases, so often adults like moreflavorful food than children.flavorful food than children.


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Taste, fast factsTaste, fast facts

Taste is instinctual. You are born likingTaste is instinctual. You are born liking

sweet flavors and disliking bitter flavors.sweet flavors and disliking bitter flavors.

There are taste receptors in the back andThere are taste receptors in the back and

roof of the mouth as well, you dont haveroof of the mouth as well, you dont have

to have a tongue to taste.to have a tongue to taste.

Smell is also a chemical sense, theSmell is also a chemical sense, the

senses of taste and smell are linked.senses of taste and smell are linked.


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Sensory InteractionSensory Interaction

The brain combines all data from theThe brain combines all data from thesenses to create a total picture orsenses to create a total picture orreality that we perceive.reality that we perceive.

If you smell something bad but tasteIf you smell something bad but tastesomething good, often the foodsomething good, often the foodexperience will be ruined.experience will be ruined.

Senses interact and your brain blendsSenses interact and your brain blendsthem together to create what you believethem together to create what you believeis actually happening.is actually happening.


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SmellSmell

Smell is one of the oldest senses.Smell is one of the oldest senses.

Smell takes place in the nasal cavity where many olfactorySmell takes place in the nasal cavity where many olfactoryreceptors react singularly to particular chemicals in the air.receptors react singularly to particular chemicals in the air.Some chemicals may trigger more than one receptor and getSome chemicals may trigger more than one receptor and getinterpreted as a separate scent.interpreted as a separate scent.

Smell can be very distinguishing, many animals can distinguishSmell can be very distinguishing, many animals can distinguishindividuals just by scent as well as some people who haveindividuals just by scent as well as some people who haveheightened smell senses (such as a blind man).heightened smell senses (such as a blind man).

Smell is the only sense that has a direct nerve hard-line to theSmell is the only sense that has a direct nerve hard-line to thelimbic system which deals with emotions and memory. This islimbic system which deals with emotions and memory. This is

why some smells can strongly evoke an emotional memory.why some smells can strongly evoke an emotional memory.


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