1. How Do we sense the world around us?
Sensation and Perception

2. Sensation vs. perception
Sensation: activation of our senses
Perception: the process of understanding these sensations

3. “The Forest Has Eyes” Bev Doolittle

4. Top-down Processing
Information processing guided by higher-level mental processes
Bottom-up Processing
Analysis that begins with the sense receptors and works up to the brain’s integration of sensory information

5. Imagine standing on a mountain on a dark, clear night
Imagine standing on a mountain on a dark, clear night. How far away would you be able to see a candle flame atop another mountain?
A. 2 miles
B. 5 miles
C. 10 miles
D. 30 miles

6. In a silent room, how far away can you hear a watch ticking?
1. 5 feet
2. 10 feet
3. 20 feet
4. 30 feet

7. thresholds
Absolute threshold: the minimum stimulation needed to detect a particular stimulus (50% of the time)

9. Signal detection theory
Predicts how and when we detect the presence of a faint stimulus (“signal”) amid background stimulation (“noise”)
Impacted by
Motivation
Expectations
Experience
Level of fatigue
Examples: new parents, airport security, a sentry standing guard

10. Impacted by: Motivation Expectations Experience Level of fatigue
Examples: new parents, airport security, a sentry standing guard

13. Difference Threshold (just noticeable difference, jnd)
Represents how much stronger one stimulus needs to be relative to another so that someone can notice that the two are not the same
Weber’s law: the ability to detect differences between two levels of a stimulus is affected by the original intensityof the stimulus (proportion rather than an amount)

14. Sensory Adaptation
Diminished sensitivity as a consequence of constant stimulation
Why does this occur?
Sensory neurons stop firing (get fatigued)
Why doesn’t this occur with vision?
Our eyes are always moving

15. Why is sensory adaptation beneficial?
It helps us pay attention to informative changes in our environment while tuning out the uninformative stimuli
“We perceive the world not exactly as it is, but as it is useful for us to perceive it.” -Meyers