Perception and Comprehension

MAR 3503

January 19, 2012

How do we take in information?

ExposureExposure

External StimuliExternal Stimuli

SightsSights

SoundsSounds

SmellsSmells

TastesTastes

Touch/MovementTouch/Movement Heat, pressure, & motor receptorsHeat, pressure, & motor receptors

TongueTongue

NoseNose

EarsEars

EyesEyes

Sensory ReceptorsSensory

Receptors

AttentionAttention

PerceptionPerception

ComprehensionComprehension

BehaviorBehavior

Psychophysics: Sensation and perception

• Sensation:– The immediate response of our sensory receptors to basic

stimuli such as light, color, sound, scent, touch, taste…– Sensation is physical

• Perception– The process by which sensations are selected and

organized– Perception is what we add to raw sensations so that we

can be interpreted– Perception is psychological

• It’s active• It’s relative

What do we perceive?• Absolute threshold

– The lowest intensity of a stimulus that can be perceived via a sensory channel

– Basic method• Ascending method of limits

– Start with a low value of a stimulus (Ex. Sound)– Increase until the person say “I hear something”

• Descending method of limits– Start with a very high value of stimulus– Decrease until the person says “I don’t hear anything”

• Absolute threshold can be quite low (indicating sensitivity)– But differs by individual

Subliminal perception

• The activation of sensory receptors by stimuli presented below the perceptual threshold

• We’re attending to a stimulus, and something flashes so quickly (e.g., 30 msec) that we can’t consciously perceive it

• Can this kind of perception influence our behavior?

Subliminal perception

• 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 admitted that “the amount of data he had collected was so small as to be useless,” but still…

• His claim opened the door to Cold War fears of subliminal propaganda

Subliminal perception works• …a little– Mere exposure showed us that subliminal perception of a

stimulus can lead to increased liking for the stimulus– Subliminal presentation of a word will lead you to

recognize that word more quickly later on– Subliminal exposure to adjectives can influence judgments

of later targets• But it’s hard to make it subliminal for everyone– May make the stimulus too weak or too strong– Need to get people to attend to the stimulus location– Need to make sure the presentation is just at the right

distance

Subliminal persuasion

• Participants 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 positively about them, and took as many coupons as they wanted for either/both drinks

Strahan, Spencer, & Zanna, 2002

Subliminal persuasion

Thirst-prime participants also chose more Super Quencher coupons (M = 5.31) than neutral prime participants (M = 4.27)

Strahan, Spencer, & Zanna, 2002

Subliminal persuasion• Participants 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

• After the priming they were given the option of two drinks, Lipton Ice or a bottled water– They picked which one they would rather have at

that moment– They rated their intentions to drink each option in

the future

Karremans, Stroebe, & Claus, 2006

Subliminal persuasion

Karremans, Stroebe, & Claus, 2006

Organizing principles of perception

• Perception is active!

• Gestalt psychology:– When we see an item, we evaluate it as a “whole

thing,” not as a collection of its tiny parts– Perception of the whole is different from (and

more important than) perception of the parts

Closure

Proximity

Similarity

Figure-Ground

Continuation

Illusions

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.

Perception is an active, constructive process. We use prior information, as well as current expectations, goals and desires when interpreting incoming information.

– The Gestalt principles give one illustration of the active nature of perception

We don’t always perceive things as they are

• Is seeing believing? Or is believing seeing?

• Belief about a product can influence perception of the product– New Coke, same old 7-up– Coors “banquet beer” versus “original draft”– “Chocolate” pudding flavors– Light-colored appliances

Our bodies, our worlds

• Our physical self can affect how we see the outside world

• People misestimate the slope of hills and distances all the time

• But when we are low on resources—encumbered by a heavy backpack, tired, 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

Proffitt, 2006

Swinging at aspirins

• Softball players were asked to estimate the size of a softball by choosing one of 8 circles

• They were also asked to report their stats• The better players chose a larger circle to

represent the ball

Witt & Proffitt, 2005

We see what we expect to see

• We perceive and interpret ambiguous stimuli in line with what we expect them to be

• Heart rate measured when they were approached by an attractive 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

Seeing what we (don’t) want to see

Comprehension

• …Is the process of understanding and giving meaning to that which we have just perceived

• …Is intertwined with perception:– We just saw how perception is expectancy-based– This can make it difficult to say where perception

ends and comprehension begins• A key component of comprehension is

categorization– …which is the process of labeling or identifying a

perceived object

Consequences of categorization

• Categorization evokes the schema of the category• A schema is a set of associations linked to a concept or

category– Ex. Luxury car

• Associations can include:• Attributes• Benefits• Drawbacks• Users• Use situations

– Associations can be:• Unique/not unique• Favorable/not favorable

Consequences of categorization

• We then apply the evoked category schema to the new target– “If this is a luxury car, then it must be…”

• Because of this categorization and schema-application, we can then more easily…– Make inferences about the new target– Evaluate the new target– Include or exclude the new target in our

consideration set– Decide whether we are satisfied/unsatisfied with the

new target

Consequences of categorization

• The application of schemas predicts that certain things will happen when categorization 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 communication, 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

Misinterpretations

• “Technically true” statements about products may encourage misinterpretations and incorrect inferences

• “Lysol kills flu and other germs on surfaces”

• “Ocean Spray cranberry juice has more food energy than orange or tomato juice”

Misinterpretation

• Some types of true statements that lead to false inference– Comparison omission• Our gasoline gives you better mileage

– Better mileage than what?

– Piecemeal information• 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 question, “If I use Oil of Olay, will I look younger?”

• Essentially, 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• Perception is an active process

– We organize what we see into meaningful stimuli– What we perceive is influenced by prior expectations, beliefs,

and desires, and often confirms those beliefs• Comprehension involves giving meaning to what we

perceive– We need to categorize new stimuli– We need to make inferences—which can lead us astray

– Next time: How does memory work?