1. Perceptual Constancies
Sensation
Vision
The Eye
Theories
Hearing
The Ear
Other Senses
Smell
Taste
Pain
Gestalt Principles
Perceptual Constancies
Perception
Basic Principles
Visual Illusions
Depth Perception
We are here

2. Sensation and Perception

3. Sensation
The process by which our sensory receptors and nervous system receive stimuli from the environment.

4. Energy v. Chemical senses
Energy Senses
Chemical Senses

5. Perception
The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

6. Sensation vs. Perception

10. Bottom-up Processing
Analysis of the stimulus begins with the sense receptors and works up to the level of the brain and mind.
Letter “A” is really a black blotch broken down into features by the brain that we perceive as an “A.”

11. THE CHT Top-Down Processing
Information processing guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations.
THE CHT

12. Example of Top-Down Processing:
Aoccdrnig to rscheearch at Cmabridge Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tigng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

13. What if we could sense everything?
Life would hurt.
So we can only take in a sliver of what is out there.
This is the study of psychophysics: relationship between physical stimuli and our psychological experiences to them.

14. Absolute Threshold
The minimum stimulation needed to detect a stimulus 50% of the time.
Ex: how far away do you need to stand to hear a watch ticking? (avg. = 20 ft)
Ex: how far away can you stand and see a candle flame in the dark at night? (avg. = 30 miles)

15. Detection No No No Yes Yes Detected Absolute Threshold Intensity
Observer’s Response
Detected
Tell when you (the observer) detect the light.

16. Absolute Thresholds: (the other 3 senses)
Taste: 1 gram (.0356 ounce) of table salt in 500 liters (529 quarts) of water
Smell: 1 drop of perfume diffused throughout a three-room apartment
Touch: the wing of a bee falling on your cheek from a height of 1cm (.39 inch)

17. Signal Detection Theory
Assumes that we do NOT have an absolute threshold.
We detect stuff based on our experiences, motivations, expectation and fatigue level.

19. Subliminal Threshold
Subliminal Threshold: When energy of the stimulus is below one’s absolute threshold for conscious awareness.
Kurt Scholz/ Superstock

20. Subliminal Perception Sensation without perception?
Quick Survey
Do you think you are influenced by everyday advertisements that you perceive consciously (e.g. movies, beverages)?
Do you think you are influenced by subliminal messages in advertising?

21. Suppose you had a choice to listen to one of two speeches that argued against a position you believe in, such as whether marijuana should be legalized. In speech A, the person presents arguments against your position; in speech B, all arguments are presented subliminally.
Which speech would you rather listen to?

22. Why are people afraid? Should you be?
69% chose speech A; 31% chose B (subliminal)
Why are people afraid? Should you be?
80% college students preferred not to receive a subliminal message b/c they thought it might influence them in an undesirable way.

23. Could 1/30th of a second really influence impressions of Al Gore?
…You Decide
Could 1/30th of a second really influence impressions of Al Gore?

24. We are not obedient to Subliminal Messages
Research shows that the effect only occurs in controlled laboratory studies
Research outside the laboratory shows no significant effect of subliminal information
We don’t blindly obey!
Placebo Effect with subliminal self help tapes

25. Subliminal Messages in Logos
Amazon has everything – from A to Z!
Fed Ex will ship your items fast! Check out the speedy arrow!
The Big 10 Conference really has 11 teams, but didn’t want to change their name.

26. EAT POPCORN

27. Vicary’s Study New Jersey, 1957:
Over 6 weeks, 45,699 people see subliminal ads
“Eat Popcorn” – sales up 57.5%
“Drink Coke” – sales up18.1%
“Minds have been broken and entered”

28. Except . . . . The Vicary “Eat Popcorn/Drink Coke” Study well. . . .
In a 1962 interview, Vicary admitted that he had made the whole thing up!

29. Backmasking
A recording studio technique where backward messages are deliberately superimposed on the soundtrack

30. Not the last of it…
Sexual imagery in ads?

34. Difference Threshold
The minimum difference that a person can detect between two stimuli.
Also known as Just Noticeable Difference (jnd)

35. Can you tell the difference?

36. Difference Threshold
Difference Threshold: Minimum difference between two stimuli required for detection 50% of the time, also called just noticeable difference (JND).
Difference
Threshold No No
Yes
Observer’s Response
Tell when you (observer) detect a difference in the light.

37. Weber’s Law
The idea that, to perceive a difference between two stimuli, they must differ by a constant percentage; not a constant amount.

38. Applying Weber’s Law
If the cost of a soda goes up by $0.25, it is very noticeable. If the cost of a television goes up by $0.25, it is not noticeable vs.
In sales – sell the more expensive item first. Then accessories or add-ons don’t seem so bad (ie, buying satellite radio for your car. After agreeing to spend $20,000, an extra $500 a year doesn’t seem ridiculous).

39. Weber fraction: k = dI/I.
Weber’s Law
Weber fraction: k = dI/I.
Stimulus
Constant (k)
Light 8%
Weight 2%
Tone 3%