module 11 introduction to sensation and perception
TRANSCRIPT
Module 11
Introduction to Sensation and
Perception
Sensation
Sensation the process by which our sensory
receptors and nervous system receive and represent stimulus energy
Perception the process of organizing and
interpreting sensory information, enabling us to recognize meaningful objects and events
Sensation
Sensationhow do we change energy into sense
Perceptionwhat do we do with our sensory information
Sensation Our
sensory and perceptual processes work together to help us sort out complex images
Sensation
Bottom-Up Processing analysis that begins with the sense
receptors and works up to the brain’s integration of sensory information (piecing lines together to recognize the number 4)
Top-Down Processing information processing guided by
higher-level mental processes as when we construct perceptions
drawing on our experience and expectations (think you know someone and as they get closer, realize that you don’t)
Sensation- Basic Principles
Psychophysics study of the relationship between
physical characteristics of stimuli and our psychological experience of them
Light- brightness Sound- volume Pressure- weight Taste- sweetness
Sensation- Thresholds Absolute Threshold
minimum stimulation needed to detect a particular stimulus 50% of the time
isn’t constant – can change with motivation and alertness
Difference Threshold minimum difference between two stimuli
required for detection 50% of the time just noticeable difference (JND)
Sensation- A. Thresholds Signal Detection Theory
predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)
assumes that there is no single absolute threshold
detection depends partly on person’s experience expectations motivation level of fatigue
Sensation- A. Thresholds
Signal Detection Theorydetection of stimuli involves decision processes as well as sensory processes
Example – riddle, shower/telephone
“You’re driving a bus with 12 passengers. At your first stop, 6 passengers get off. At the second stop, 3 get off. At the third stop, 2 more get off, but 3 new people get on. What color are the driver’s eyes?
Did you detect the signal – who is the driver? – over the noise – number of passengers?
Sensation- A. Thresholds
Subliminal when stimuli
are below one’s absolute threshold for conscious awareness
0
25
50
75
100
Low Absolutethreshold
Medium
Intensity of stimulus
Percentageof correctdetections
Subliminal stimuli
Sensation- A. Thresholds
Subliminal Messages
Reverse Speech - Voices From The Unconscious
Sensation- Thresholds
Difference Threshold minimum difference between two
stimuli required for detection 50% of the time
just noticeable difference (JND) – we experience the difference threshold as a JND.
Read the passage at the right.
How many lines do you require to experience a noticeable difference?
Sensation- D. Thresholds
Weber’s Law to be perceived as different, two
stimuli must differ by a constant minimum percentage (rather than a constant amount) light intensity- 8% (1/60) weight- 2% (1/50) tone frequency- 0.3% (1/333)
Sensation- D. Thresholds
Sensory Adaptation diminished sensitivity as a
consequence of constant stimulation(wearing a new wristwatch)
Selective Attention focusing of conscious awareness
on a particular stimulus as in the cocktail party effect
(listen to one voice, among many)
Now you see it, now you don’t!
Perception
Selective Attention
Do you see circles with white lines or a cube?
Because attention is selective, you only see one interpretation at a time.
Change Blindness
Change Blindness is an example of Selective Attention
Lab Demos
Change Blindness