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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.