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How do we take in informa&on?
Exposure
External S&muli
Sights
Sounds
Smells
Tastes
Touch/Movement Heat, pressure, & motor receptors
Tongue
Nose
Ears
Eyes
Sensory Receptors
ANen&on
Percep&on
Comprehension
Behavior
Psychophysics: Sensa&on and percep&on
• Sensa&on: – The immediate response of our sensory receptors to basic s&muli such as light, color, sound, scent, touch, taste…
– Sensa&on is physical • Percep&on
– The process by which sensa&ons are selected and organized
– Percep&on is what we add to raw sensa&ons so that we can be interpreted
– Percep&on is psychological • It’s ac&ve • It’s rela&ve
What do we perceive? • Absolute threshold
– The lowest intensity of a s&mulus that can be perceived via a sensory channel
– Basic method • Ascending method of limits
– Start with a low value of a s&mulus (Ex. Sound) – Increase un&l the person say “I hear something”
• Descending method of limits – Start with a very high value of s&mulus – Decrease un&l the person says “I don’t hear anything”
• Absolute threshold can be quite low (indica&ng sensi&vity) – But differs by individual
Subliminal percep&on
• The ac&va&on of sensory receptors by s&muli presented below the perceptual threshold
• We’re aNending to a s&mulus, and something flashes so quickly (e.g., 30 msec) that we can’t consciously perceive it
• Can this kind of percep&on influence our behavior?
Subliminal percep&on
• In 1957, James Vicary repeatedly flashed a frame-‐long image that read either “Drink Coke” or “Eat popcorn” during a movie
• He claimed that popcorn sales increased 58% and soda sales increased 18%
• He later admiNed that “the amount of data he had collected was so small as to be useless,” but s&ll…
• His claim opened the door to Cold War fears of subliminal propaganda
Subliminal percep&on works • …a liNle
– Mere exposure showed us that subliminal percep&on of a s&mulus can lead to increased liking for the s&mulus
– Subliminal presenta&on of a word will lead you to recognize that word more quickly later on
– Subliminal exposure to adjec&ves can influence judgments of later targets
• But it’s hard to make it subliminal for everyone – May make the s&mulus too weak or too strong – Need to get people to aNend to the s&mulus loca&on – Need to make sure the presenta&on is just at the right distance
Subliminal persuasion
• Par&cipants were thirsty when they came into the lab • They then were exposed to subliminal thirst primes or neutral primes, to make sure thirst was on their mind
• They then read about two sports drinks: Power Pro (the best electrolyte balancing drink) and Super Quencher (the more thirst quenching drink)
• They then rated the two products as to how much they felt posi&vely about them, and took as many coupons as they wanted for either/both drinks
Strahan, Spencer, & Zanna, 2002
Subliminal persuasion
Thirst-‐prime par&cipants also chose more Super Quencher coupons (M = 5.31) than neutral prime par&cipants (M = 4.27)
Strahan, Spencer, & Zanna, 2002
Subliminal persuasion • Par&cipants were brought into the lab and given a salty treat that made them thirsty, or given no treat
• Then they were subliminally primed with the words “Lipton Ice,” which is a brand of iced tea
• Aker the priming they were given the op&on of two drinks, Lipton Ice or a boNled water – They picked which one they would rather have at that moment
– They rated their inten&ons to drink each op&on in the future
Karremans, Stroebe, & Claus, 2006
Organizing principles of percep&on
• Percep&on is ac&ve!
• Gestalt psychology: – When we see an item, we evaluate it as a “whole thing,” not as a collec&on of its &ny parts
– Percep&on of the whole is different from (and more important than) percep&on of the parts
How do we perceive?
• One commonly-‐held view – Realism: We see the world as it is. We simply register sensory inputs and report them back.
• Another (more accurate) view: – Naïve realism: We believe we see the world as it is. Percep&on is an ac&ve, construc&ve process. We use prior informa&on, as well as current expecta&ons, goals and desires when interpre&ng incoming informa&on.
– The Gestalt principles give one illustra&on of the ac&ve nature of percep&on
We don’t always perceive things as they are
• Is seeing believing? Or is believing seeing?
• Belief about a product can influence percep&on of the product – New Coke, same old 7-‐up – Coors “banquet beer” versus “original drak” – “Chocolate” pudding flavors – Light-‐colored appliances
Our bodies, our worlds
• Our physical self can affect how we see the outside world
• People mises&mate the slope of hills and distances all the &me
• But when we are low on resources—encumbered by a heavy backpack, &red, older—we see the same slopes and distances as steeper or longer
• When we have added resources, even social ones, these same obstacles appear less difficult to overcome
ProffiN, 2006
Swinging at aspirins
• Sokball players were asked to es&mate the size of a sokball by choosing one of 8 circles
• They were also asked to report their stats • The beNer players chose a larger circle to represent the ball
WiN & ProffiN, 2005
We see what we expect to see
• We perceive and interpret ambiguous s&muli in line with what we expect them to be
• Heart rate measured when they were approached by an aNrac&ve female assistant
• Heart rate increased not for those who drank only tonic (Groups 3 & 4), but instead for those who thought they only drank tonic
Told was vodka & tonic Told was only tonic
Drank vodka & tonic Group 1 Group 2
Drank only tonic Group 3 Group 4
Comprehension
• …Is the process of understanding and giving meaning to that which we have just perceived
• …Is intertwined with percep&on: – We just saw how percep&on is expectancy-‐based – This can make it difficult to say where percep&on ends and comprehension begins
• A key component of comprehension is categoriza&on – …which is the process of labeling or iden&fying a perceived object
Consequences of categoriza&on
• Categoriza&on evokes the schema of the category • A schema is a set of associa&ons linked to a concept or category – Ex. Luxury car
• Associa&ons can include: • ANributes • Benefits • Drawbacks • Users • Use situa&ons
– Associa&ons can be: • Unique/not unique • Favorable/not favorable
Consequences of categoriza&on
• We then apply the evoked category schema to the new target – “If this is a luxury car, then it must be…”
• Because of this categoriza&on and schema-‐applica&on, we can then more easily… – Make inferences about the new target – Evaluate the new target – Include or exclude the new target in our considera&on set
– Decide whether we are sa&sfied/unsa&sfied with the new target
Consequences of categoriza&on
• The applica&on of schemas predicts that certain things will happen when categoriza&on goes wrong
• We may make incorrect inferences about what the target is, and what it should do – Sunlight Dishwashing Detergent – Maalox Whip Antacid
• So, it’s important that people categorize your product correctly so that the right schema is evoked
Comprehension: Inferences
• To be successful at communica&on, we need to make inferences – “My pen stopped working” – “It’s hot in here” – “Do you know how to get to the Reitz Union?”
• Inferences are usually beneficial, but our tendency to make inferences can lead us astray
Misinterpreta&ons
• “Technically true” statements about products may encourage misinterpreta&ons and incorrect inferences
• “Lysol kills flu and other germs on surfaces”
• “Ocean Spray cranberry juice has more food energy than orange or tomato juice”
Misinterpreta&on
• Some types of true statements that lead to false inference – Comparison omission • Our gasoline gives you beNer mileage
– BeNer mileage than what?
– Piecemeal informa&on • Our car has more headroom than a Mercedes, more legroom than a Cadillac, more trunk space than a BMW
– Affirming the consequent • Women who look younger use Oil of Olay
– Does not answer the ques&on, “If I use Oil of Olay, will I look younger?”
• Essen&ally, it is this argument: – If P, then Q. – Q is true. – Therefore, P is, too.
• The problem is that P isn’t the only possible cause of Q. – If Bill Gates owns Fort Knox, then Bill Gates is rich. – Bill Gates is rich. – Therefore, Bill Gates owns Fort Knox.
Affirming the consequent
Summary • There are methods for measuring what will and will not be
perceived • Subliminal may have small, but not large, effects on
behavior • Percep&on is an ac&ve process
– We organize what we see into meaningful s&muli – What we perceive is influenced by prior expecta&ons, beliefs, and desires, and oken confirms those beliefs
• Comprehension involves giving meaning to what we perceive – We need to categorize new s&muli – We need to make inferences—which can lead us astray
– Next &me: How does memory work?