Sensation Intro

8/4/2019 Sensation Intro

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DO NOW QUESTION:Write out your response...

Are you influenced byadvertisements?


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Sensation


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SensationThe process by which our

sensory receptors andnervous system receivestimulus from the

environment.


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Perception

The process of organizingand interpreting sensoryinformation, enabling us torecognize meaningfulobjects and events.


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What if we could senseeverything?

Life would hurt.So we can only takein a window of what is

out there.

This is the study ofpsychophysics:

relationship betweenphysical stimuli and ourpsychologicalexperiences to them.


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Absolute Threshold

*The minimum stimulation needed to detect a stimulus 50% of the time.

For a specific type of

sensory input, it is theminimum amount ofstimulation that anorganism can detect.


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Difference Threshold

The minimum difference that a personcan detect between two stimuli.

Also known as JND - Just Noticeable

Difference


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We have a very sensitiveabsolute threshold forvision, only 3 photons onsingle receptor across amoment of time willtrigger a detection.

Our other modalities aresensitive, thoughchemically we havenothing over sharks

Sharks can detect asingle drop of blood inthousands of gallons ofwater whereas we cantaste a teaspoon ofsugar in only 2 gallons.


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Webers LawThe idea that, to perceive a

difference between 2stimuli, they must differ bya constant percentage; nota constant amount.

Example:Weber found that the JND between 2

weights was approximately proportional tothe mass of the weights.Thus, if 105 g can be distinguished from100 g, the JND is 5 g.If the mass is doubled, the differentialthreshold also doubles to 10 g, so that 210

g can be distinguished from 200 g.


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Webers Law Experiment

Get students to form into groups.

Give each group two envelopes and ask them to put one 20c piece inone envelope and two 20c pieces in the other.

Invite each member of the group to hold both envelopes, one in eachhand. They should be able to easily distinguish which is the heavier

envelope. Now ask for a volunteer in each group to take off their shoes (or use two

textbooks if they dont want to take off their shoes). Get the students toput one envelope in each shoe or each textbook. Now if they hold oneshoe/textbook in each hand they will find that it is no longer easy to saywhich is heavier. Because the shoes weigh more, the difference betweenthe shoes must be greater for us to notice the difference.

Webers law: Difference thresholds grow with the magnitude of thestimulus, because the difference is a percentage of the magnitude of thestimulus, not a constant amount.

Ask students for examples of Weber's principle in their everyday life


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Signal Detection Theory

Predicts how we detect a

stimulus amid otherstimuli.

Assumes that we do not

have an absolutethreshold.

We detect stuff based

on our experiences,motivations andfatigue level.


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Subliminal Stimulation

Below ones absolute

threshold for conscious

awareness.

Does this work?

Yes and No

Slide studies showed some emotionalreactivity (called priming a response).

The effects are subtle and fleeting.


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Derren Brown Videos

Advertising Execs

Grocery Store Exec


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Bush-Gore Campaign Ad


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Sensory Adaptation

Diminished sensitivity

as a result of constantstimulation.

We don't really detectphysical energy

Our senses are moreevolved to detect changes

in physical energy

As such, if there are nochanges in our physicalenvironment, we adapt tothe static energy levels and

cease to notice them, Thisis sensory adaptation.


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We do not perceive theworld how it really is, but

as it is useful for us toperceive it.


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Selective AttentionThe focusing of conscious

awareness on a particular stimulus.


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An example of

selectiveattentionis:

Cocktail Part Effect

ability to listen toone voice among

many.

Sensation Intro

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