Sensation & PerceptionSensation & Perception

Lecture 6Lecture 6

2/09/042/09/04

Scent of a WomanScent of a Woman

• Does smell really signify attractiveness?

From Scentsational Sex: The Secret to From Scentsational Sex: The Secret to Using Aroma for Arousal, 1998Using Aroma for Arousal, 1998

“PPL are powerfully influenced no by manly, sweet, or earthy colognes, but by odd mixtures of everyday odors- pumpkin pie and lavender for men, or licorice candy mixed with cucumber for women”

Sniffing out the truthSniffing out the truth

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How does physical energy become How does physical energy become a psychological experience?a psychological experience?

• Sensation– Sensory receptors in eyes, ears, nose absorb

raw, physical energy

• Transduction– Raw energy converted to neural signals to be

sent to brain

• Perception– Signals selected, organized & interpreted

Example- VisionExample- Vision

Sunset

Sensory receptors in eyes

Neural impulses (Chemical rxn of light sensitive cells)

Brain (occipital lobe)

Importance of SmellImportance of Smell

• Past: used sweat, brain, urine, odor to diagnose illness– Today: Aromatherapy (inhalation of odors) to ward off

illness

• Dogs have 200 million olfactory receptors, we have only 10 million– Dogs mark territory, signal danger, establish

dominance, attract mates, track down animals, criminals, drugs, disease…

• Can our behavior influenced by odor?

How our nose knowsHow our nose knows

1. Breathe through nose and mouth to inhale airborne oderant molecules

2. Molecules dissolved and trapped by olfactory receptors

3. Like lock & key, AP activated in olfactory bulb

4. Info DIRECTLY distributed throughout cortex & limbic system

• What do I smell, how do I feel about that smell, have I smelled that before & Awareness

Olfactory SystemOlfactory System

• We can distinguish among 10,000 different odor molecules– Primary odors are vinegar, rose, mint, rotten

egg, mothballs, dry-cleaning fluid, musk

– Women > men in ID-ing different smells• Some are anosmic (Ben Cohen)

Individuals differ in smelling sensitivity

AgeAge

• Nursing infants (2wks) prefer their own mother’s body odor to others.

• Olfactory sensitivity peaks in middle age and declines in 70’s + 80’s– Based on National Geographic scratch n’ sniff

recognition test.

How early?How early?

• Expose fetal rat pups to lemon scent– Nursing preference– Place-preference task– Mate preference

How sensitive to scent are we?How sensitive to scent are we?

• Sniffing Studies– College students can ID own shirts– Mothers can pick out children’s– Most can ID Men vs. women– Women can ‘sniff’ attractive men

PheromonesPheromones

• Chemicals secreted by animals of same species to transmit signals

• Dogs in heat…

• E.g. male Emperor Moth– Chemoreceptors on antennae can detect

scent of virgin female > 6 miles away!

4 categories of behavior affected by 4 categories of behavior affected by PheromonesPheromones

1. Mother-Infant Interaction

2. Territorial Marking

3. Reproductive Synchrony

4. Sexual Attraction

““if you had to smell it all the time”if you had to smell it all the time”

• 49 unmarried women• Chose smell of genetically similar men to

fathers

• Women who had pheromone added to perfume reported 50% increase in sexual attention from men– Sexual intercourse, kissing, heavy petting,

affection, slept closer

Fragrance enhanced performanceFragrance enhanced performance

Yale Chocolate Study, 1991

21 14

13 14

RETESTLE

AR

NIN

G Odor

No

Odor

Odor No Odor

Fragrance & ArousalFragrance & Arousal

• Write description of personality– Exchange with partner

• Rate partner– Exchange

• Angry vs. Nonangry

• “Aggression Machine”– Jungle gardenia vs. no scent

Fragrance enhances aggressionFragrance enhances aggression

NO SCENT PERFUME

NOT ANGRY 3 2

ANGRY 3 4

Organization and interpretation of visual information

How well do our senses sense?How well do our senses sense?

• Experience is subjective

• The same visual input can result in radically different perceptions– Psychophysics

• Relationship between physical stimulation AND subjective sensations

– Signal Detection Theory• Detection based on signal AND response criterion

• Center figure depends on the order in which one looks at the figures:– If scanned from the left, man’s face – If scanned from the right, a woman’s figure

Perceptual Set

Perceptual Set: Letter B or Number 13?

Gestalt Principles AppliedGestalt Principles Applied

1. Figure & Ground– Dividing visual displays into the THING

being looked at and the BACKGROUND against which it stands• THING has substance, stands in front of ground

• Fundamental Attribution Error– Discounting the situation, attributing

behavior to dispositions• Why did she litter? And you?

Gestalt Laws of GroupingGestalt Laws of Grouping

• We tend to group collections of shapes, sizes, colors, and other features into perceptual wholes

• Proximity– Seeing 3 pair of lines in A

• Similarity– Seeing columns of orange

and red dots in B

• Continuity– Seeing lines that connect

1 to 2 and 3 to 4 in C

• Closure– Seeing a horse in D

StereotypesStereotypes

• Generalizations about groups with identical characteristics

• We tend to see members of stereotyped groups as more similar to stereotype than they actually are

• Cliques, sports teams, majors, Greek life

• Read description of b-ball player…

White men can’t jump, 1997White men can’t jump, 1997

ClosureClosure

• The Zeingarnik Effect– Tendency to remember an uncompleted task

rather than a completed one– Unfinished business creates “psychic tension”

• Tension motivates us to seek closure by completing the task

Highly adept, yet often fooledHighly adept, yet often fooled

S.B.S.B.

• Blind until 52

• Corneal Transplant performed, sight restored

• Looked out hospital window– Small objects below

• Climbed out on 4th floor ledge to check them out by lowering himself with hands!– No depth perception

• Visual illusion of a cliff

• At which point in dvlptl process can humans perceive depth

• Nativist vs. empiricist perspective

The Visual CliffEleanor Gibson & Richard Walk, 1960

ProcedureProcedure

• 36 infants 6-14 months

• Placed on ‘shallow side’

• Mothers called from deep side

• *also chicks, turtles, rats, lambs, kids, pigs & kittens

ResultsResults

• ALL p’s crawled when called from shallow side

• ONLY 3 crept across “cliff”

• Animal abilities varied by when skill was needed for survival– Chicks less than 24hrs made no mistakes– Rats showed no preference

Binocular Cues to DepthBinocular Cues to Depth

– Perceived length of line altered by position of other lines enclosing it

The Müller-Lyer Illusion

– Illusion in which the perceived line length is affected by linear perspective cues.

• Side lines seem to converge

• Top line seems farther away– But the retinal images

of the red lines are equal.

The Ponzo Illusion