1. Sensation and Perception
Sensation vs. Perception
What’s the Difference?
Transduction: Converting incoming signals into neural activity
Sensation: Sensory receptors/nervous system receive information from environment
Perception: Organizing and interpreting sensory information to create a meaningful experience

2. Sensation and Perception
Top-Down Processing:
Recognition guided by higher level cognitive processes
Connected to our Mental Representations
“What do IEXPECT to perceive?”
(Then you perceive that)
Bottom-Up Processing:
Recognition depends on information received by senses and then processed by the brain
“I don’t know what to expect, so I guess I’ll just figure out after I sense it”

3. What’s this painting about. What do you EXPECT to perceive
What’s this painting about? What do you EXPECT to perceive? Study it a minute before moving on…

4. How many of the 13 faces did you see
How many of the 13 faces did you see? Go back to the last one and watch how fast your brain changes perception based on expectations

5. Sensation and Perception
Top-Down Processing: Recognition guided by higher level cognitive processes
Bottom-Up Processing: Recognition depends on information received by senses and then processed by the brain

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

8. The next slide is an actual photograph, adjusted to pure black and white.
Use “Bottom-Up” to see if you can figure it out…

10. Did you see it? Most don’t.
You didn’t have any expectations set up for it!
Click to the next slide and study it for a minute, then return to the original black and white.
Your brain just adjusted to the new expectations!

12. Sensation and Perception
Selective Attention
You have VERY limited attention resources
Cocktail Party Effect
You can focus on your attention on one stimulus (at the expense of tuning out the rest

13. Sensation and Perception
Selective Attention
Inattentional Blindness
Example 1
Example 2
Change Blindness
Whodunnit
(AFTER watching, make sure you click back to the opening scene)
Gradual Change
Door Experiment

14. Sensation and Perception
Signal Detection Theory
You haven’t read this yet, but the chart is helpful when you do 
Was Stimulus Present?
YES NO
HIT
FALSE ALARM
(Type I Error)
MISS
(Type II Error)
CORRECT REJECTION
Was Stimulus Reported?

15. Sensation and Perception
Signal Detection Theory
Apply to: Soldier in the field at night hears a noise
Doctor assesses a patient who thinks they have cancer
Jury determining guilt for 1st Degree Murder
Was Stimulus Present?
YES NO
HIT
FALSE ALARM
(Type I Error)
MISS
(Type II Error)
CORRECT REJECTION
Was Stimulus Reported?