Thinking About Psychology: The Science of Mind and Behavior

1. Thinking About Psychology: The Science of Mind and Behavior Charles T. Blair-Broeker Randal M. Ernst

2. Sensation and Perception Chapter 04

3. Sensation Module 09

4. Introduction Module 9: Sensation

5. Sensation • The process by which our sensory systems (eyes, ears, and other sensory organs) and nervous system receive stimuli from the environment • A person’s awareness of the world

6. Bottom-Up Processing • Information processing that focuses on the raw material entering through the eyes, ears, and other organs of sensation

7. Perception • The process of organizing and interpreting sensory information

8. Top-Down Processing • Information processing that focuses on expectations and experiences in interpreting incoming sensory information

9. Thresholds Module 9: Sensation

10. Threshold • An edge or a boundary

11. Absolute Threshold • The minimum difference that a person can detect between two stimuli 50% of the time • Also called just noticeable difference

12. Absolute Threshold

13. Thresholds: Signal Detection Theory Module 9: Sensation

14. Signal Detection Theory • Set of formulas and principles that predict when we will detect the presence of a faint stimulus (signal) amid background stimulation (noise) • Developed out of the Cold War

15. Signal Detection Theory • Three kinds of variables • Stimulus variables • Environmental variables • Organismic variables

16. Sensory Adaptation Module 9: Sensation

17. Sensory Adaptation • Diminished sensitivity as a result of constant stimulation • If a stimulus is constant and unchanging, eventually a person may fail to respond to it

18. Selective Attention Module 9: Sensation

19. Selective Attention • Focusing conscious awareness on a particular stimulus to the exclusion of others • The ability to focus on one stimulus at a time • Allows a person to function in a world filled with many stimuli

20. Selective Attention • Insert “Neisser’s Selective Attention Test” Video #23 from Worth’s Digital Media Archive for Psychology. • Instructions for importing the video file can be found in the ‘Readme’ file on the CD-ROM.

21. The Visual System: The Nature of Light Module 9: Sensation

22. Electromagnetic Energy • An energy spectrum that includes X-rays, radar, and radio waves • A small portion of the spectrum includes light visible to the human eye

23. The Electromagnetic Spectrum

24. Hue • The color of light as determined by the wavelength of the light energy • Includes: red, orange, yellow, green, blue, indigo and violet (ROY G BIV) • The eye can detect 7 million separate hues

25. Wavelength

26. Amplitude • The brightness of light as determined by height of the wave • The taller the wave, the brighter the color

27. Amplitude

28. The Visual System: The Structure of the Visual System Module 9: Sensation

29. Cornea • The clear bulge on the front of the eyeball • Begins to focus the light by bending it toward a central focal point • Protects the eye

30. Parts of the Eye – Cornea

31. Iris • A ring of muscle tissue that forms the colored portion of the eye; creates a hole in the center of the iris (pupil) • Regulates the size of the pupil by changing its size--allowing more or less light to enter the eye

32. Parts of the Eye - Iris

33. Pupil • The adjustable opening in the center of the eye that controls the amount of light entering the eye (surrounded by the iris) • In bright conditions the iris expands, making the pupil smaller. • In dark conditions the iris contracts, making the pupil larger.

34. Parts of the Eye - Pupil

35. Lens • A transparent structure behind the pupil; focuses the image on the back of the eye (retina) • Muscles that change the thickness of the lens change how the light is bent thereby focusing the image • Glasses or contacts correct problems in the lens’ ability to focus.

36. Parts of the Eye - Lens

37. Inverted Images • Play “Perception: Inverted Vision” (5:04) Module #10 from The Brain: Teaching Modules (2nd edition).

41. Retina • Light-sensitive surface with cells that convert light energy to nerve impulses • At the back of the eyeball • Made up of three layers of cells • Receptor cells • Bipolar cells • Ganglion cells

42. Parts of the Eye - Retina

43. Receptor Cells • These cells are present in every sensory system to change (transduce) some other form of energy into neural impulses. • In sight they change light into neural impulses the brain can understand. • Visual system has two types of receptor cells – rods and cones

44. Rods • Visual receptor cells located in the retina • Can only detect black and white • Respond to less light than do cones

45. Cones • Visual receptor cells located in the retina • Can detect sharp images and color • Need more light than the rods • Many cones are clustered in the fovea.

47. Fovea • The central focal point of the retina • The spot where vision is best (most detailed)

48. Parts of the Eye - Fovea

49. Bipolar Cells • Gather information from the rods and cones and pass it on to the ganglion cells • Cells that form the middle layer in the retina

50. Ganglion Cells • Pass the information from the bipolar cells through their axons • Together these cells form the optic nerve. • The top layer of the cells in the retina