Chapter 5: Sensation and Perception
➢ Psychophysics What do Weber fractions tell you about sensation?
➢ Subliminal Perception Can we perceive subliminal messages?
➢ Visual System How does the visual system work?
Next time: More vision
Scan: pg. 143-151
How do we perceive the world around us?
- Psychophysics and psychophysiology
- Relation between physical stimulus and psychological response
- Fechner: Father of psychophysics
- Can determine a just noticeable different (JND)
- Value of a stimulus characteristic required to produce some response
- Absolute: Lower limit
- Difference: amount of change for JND
Weber’s Law (need to know how to calculate it):
- Size of the difference threshold relative to physical intensity of test constant
- If I= 50db and a JND is report at 55db
o 5/50= 1/10
- can predict other JND’s
o whats a JND @ 100 db?
▪ x/100=1/10 ..solve for x
- the value if JND not constant
- can compare sensitivity of different systems
- sensation incr