1. Sensation and Perception

2. Agenda Test Sunday Sensation/Perception Processes Test Review
7:00 pm in B59 R1001
Sensation/Perception Processes
Test Review

3. Sensation
Sensation: Activation of sensory organs by energy from the environment.
1.) Detection: Receptor cells
2.) Transduction: encoding
3.) Transmission to brain
Perception: Selecting, organizing, interpreting neural signals

4. Demonstration

5. The Right Side
The duck loves to splash in deep puddles.

6. The Left Side
The rabbit loves to hop in the tall grass.

12. Process Everyone Some People Bottom-Up Processing Top Down Processing
Detects light
Interprets contrasting intensities in space
Assigns basic description
Bottom-Up Processing
Some People
Interpret the images further
Assign subjective meaning
Top Down Processing

13. Bottom-up processing: Start at detection, then interpretation
Top-down processing: Perception influenced by experience, motivation, expectations.

14. Reification: we see more spatial information than what is actually there.

15. Multistability: Switch between two different interpretations of an ambiguous image

16. Perception Laws
Law of Closure
Fill gaps in stimuli

17. Law of Proximity
Group close figures together

18. Law of Similarity
group together similar stimuli

19. Law of Continuity
Perceive continuous patterns

20. Limited to Vision?

21. Sensation-Perception Interaction
Perception is affected by other senses.
Smell-Taste
Hearing-Sight
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22. Detection
Detection: the point at which our sensory organs are activated
Absolute thresholds
Smallest amount we can sense
Detect 50% of the time

23. Absolute Thresholds

28. Detection Signal Detection Theory Sensory adaptation:
Environment/Internal factors
Signal/noise ratio
Experience
Expectations
Motivation
Fatigue
Sensory adaptation:
Detection decreases over prolonged exposure

29. Detection Just Noticeable Difference (JND):
Minimum change needed to detect a difference.
Weber’s law:
The JND is a constant ratio.
Light: 8%
Weight: 2%
Tones: 0.3%

30. Hearing Sound waves Amplitude: Frequency: height of wave, loudness
length of wave, pitch.

31. Hearing Stereophonic hearing: locate sound.
Sounds above, in front, behind
Sound waves hit right ear before left

32. A Note On Transduction

33. Vision
Amplitude:
intensity
Frequency
hue

34. A Note on Anatomy Cornea bends light, protects eye
Light passes through Pupil
Opening adjusted by iris, sensitive to light intensity
Lens focuses rays on back of the retina
Fovea: central focal point.
Blind spot: area where the optic nerve gathers together.

35. The Retina Rods Cones Detect color Detect black, white, gray Daylight
Peripheral, twilight vision
120 million
More light sensitive
Cones
Detect color
Daylight
Concentrated around the fovea
6 or 7 million
More detail sensitive

36. Colorblindness Red-Green (most common) Blue-yellow also exists
Sex linked: primarily affects males
7% Males, .4% Females

37. 1. 2. 3. 4. 5. 6.

38. Touch
Pressure
Warmth
Cold
Pain

39. Pain What might influence pain?
Attention, expectations, physiology, experience, cultural norms
Phantom limbs

40. Gate-Control Theory of Pain
What causes pain?
Your brain
Spinal cord can block pain transmission to brain
Different types of nerve fibers
Small = “open” neural gate
Large = “close” gate
Rubbing, electrical stimulation
So do endorphins, distraction

41. Taste Sweet, Sour, Salty, Bitter Facts about taste: Umami?
Not localized on tongue
Evolution: fatty, sweet, salty
Sour = rotted, bitter = poison