1. Sensation & Perception

2. What’s the Difference? Sensation: Perception:
Process by which our sensory receptors and nervous system receive stimuli from the environment
Perception:
Process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

3. Sensation vs. Perception

4. Psychologists distinguish between two types of processes in perception:
Bottom-up processing: perception begins with the stimulus itself
2. Top-down processing: refers to the use of contextual information in pattern recognition

5. Richard Gregory, 1970s Top-down Processing
Perception involves a lot of hypothesis testing to make sense of the information presented to the sense organs.
Our perceptions of the world are hypotheses based on past experiences and stored information.
The formation of incorrect hypotheses will lead to errors of perception.

6. This object appears to flip between orientations because the brain develops two equally plausible hypotheses and is unable to decide between them.

8. Let’s Take a Look at Charlie Chaplin
Charlie Chaplin's Face

9. What's Up?!

10. Psychophysics
Study of the relationship between the physical characteristics of stimuli and our psychological experience of them.

11. Absolute Threshold
Minimum stimulation necessary to detect a particular stimulus 50% of the time
Absolute thresholds vary with:
Our age
Our psychological state

12. Signal Detection Theory
Tries to predict when we will react to a weak signal (stimulus)
Whether we will detect a weak stimulus depends on motivation, expectations, and experience
Examples
Mom of a newborn
Soldier in combat
Someone who plays video games

13. What is a “subliminal” stimulus?
A stimulus that is detectable LESS than 50% of the time.
They are below absolute threshold.
Helps account for those times when we “feel” what we can’t put words to (intuition?)
An Advertising Campaign

14. Who eats Skittles Anyways?

15. Are Your Thirsty?

16. A Nice Picture in a Children’s Book

17. The Big Message
Much of our information processing occurs automatically, out of sight, off the radar screen of our conscious mind.

18. Difference Thresholds
Just Noticeable Difference
Minimum difference a person can detect between any to stimuli 50% the time
The detectable difference increases with the size of the stimulus

19. Weber-Fechner’s Law
For people to really perceive a difference, the stimuli must differ by a constant "proportion" not a constant "amount"

20. Sensory Adaptation

21. Is There Visual Adaptation?
Sensory Adaptation Activity