1. Chapter 4 Sensation & Perception

2. Sensation
The process by which stimulation of a sensory receptor produces neural impulses that the brain interprets as sound, a visual image, an odor, a taste, a pain, or other sensory images.
The registration of information.

3. Perception
A process that makes sensory patterns meaningful.

4. How Do We Interpret Sensations?
STIMULUS - energy that affects what we do.
RECEPTORS – specialized cells that convert environmental energies into signals for the nervous system.

5. How Does Stimulation Become Sensation?
The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural impulses.

6. Transduction
Transformation of one form of energy into another – especially the transformation of stimulus information into nerve impulses.

7. Sensory pathways – Bundles of neurons that carry information from the sense organs to the brain.

8. Sensory Adaptation
Loss of responsiveness in receptor cells after stimulation has remained unchanged for a while.

9. Thresholds
Absolute threshold – Amount of stimulation necessary for a stimulus to be detected.
Difference threshold – Smallest amount by which a stimulus can be changed and the difference be detected (also called just noticeable difference – JND).

10. Approximate absolute thresholds for the 5 senses:
Vision - Candle flame seen at miles on a clear, dark night.
Hearing - Tick of a watch under quiet conditions at 20 feet.
Taste - 1 Teaspoon of sugar in 2 gallons of water.
Smell - 1 Drop of perfume diffused into a three-room apartment.
Touch - A bee's wing falling on your cheek from 1 centimeter above.

11. Thresholds Weber’s law
The JND is always large when the stimulus intensity is high, and small when the stimulus intensity is low.

12. Signal Detection Theory
Signal detection theory – Perceptual judgment as a combination of sensation and decision-making processes.
Stimulus event
Neural activity
Comparison with personal standard
Action (or no action)

13. Subliminal Persuasion
Studies have found that subliminal words flashed briefly on a screen can “prime” a person’s later responses.
No controlled research has ever shown that subliminal messages delivered to a mass audience can influence people’s buying habits.

15. THE EYE
Video

16. The Structure of the EYE
PUPIL – an adjustable opening in the eye through which light enters.
IRIS – the colored structure on the surface of the eye.

17. The Structure of the EYE
CORNEA – a rigid transparent structure on the outer surface of the eyeball.
LENS – a flexible structure that can vary in thickness, enabling the eye to accommodate.

18. The Structure of the EYE
RETINA – a layer of visual receptors covering the back surface of the eyeball.

19. Visual Sensation Retina:
Photoreceptors – Light-sensitive cells in the retina that convert light energy to neural impulses.
Rods – Sensitive to dim light but not colors.
Cones – Sensitive to colors but not dim light.
Fovea – Area of sharpest vision in the retina.

20. Visual Receptors 7 million Cones color vision daytime detailed
5-10% of visual receptors in the retina are cones
7 million

21. Visual Receptors
Rods
night vision
black and white
125 million

22. Interactive

23. The Visual Pathway
Optic nerve – Bundle of neurons that carries visual information from the retina to the brain.

24. The Visual Pathway Blind spot –
The point where the optic nerve exits the eye and where there are no photoreceptors.
DO IT YOURSELF!
page 122

25. In which area of the brain are visual signals processed???
Review from Chapter 3!!!
In which area of the brain are visual signals processed???

26. Answer:
VISUAL CORTEX
Part of the brain in the occipital lobe where visual sensations are processed.

27. Neural Pathways in the Human Visual System

28. How the Visual System Creates Color
Electromagnetic spectrum – Entire range of electromagnetic energy, including radio waves, X-rays, and visible light.
Visible spectrum – Tiny part of the electromagnetic spectrum to which our eyes are sensitive.

29. How the Visual System Creates Brightness
Wavelength
Intensity (amplitude)
Color
Brightness

30. Trichromatic Theory
The idea that colors are sensed by 3 different types of cones; explains the earliest stage of color sensation.
Blue
Green
Red

31. Opponent-Process Theory
We perceive color not in terms of independent colors but in terms of a system of paired opposites.
Red vs. Green
Yellow vs. Blue
White vs. Black

32. Afterimages Sensations that linger after the stimulus is removed.
Most often called negative afterimages
Try the activity on page 121

33. Color Blindness
Vision disorder that prevents an individual from discriminating certain colors.

34. Red-Green Colorblindness
Difficulty distinguishing red from green and either red or green from yellow.

35. The Camera
When you look at an object, light rays are reflected from the object and enter the eye through the pupil. 
The light rays are bent, refracted and focused by the lens. The lens' job is to make sure the rays come to a sharp focus on the retina. The resulting image on the retina is upside-down. 
Here at the retina, the light rays are converted to electrical impulses which are then transmitted through the optic nerve, to the brain, where the image is translated and perceived in an upright position!

36. Hearing

37. Hearing The Physics of Sound Amplitude – Physical strength of a wave.
High Amplitude
Low Amplitude

38. Hearing The Physics of Sound
Frequency – Number of cycles completed by a wave in a given amount of time, usually a second.
Low Frequency
High Frequency

39. Hearing
Hertz (Hz) – unit of frequency representing one cycle (vibration) per second.

41. How Sound Waves Become Auditory Sensations
Tympanic membrane – The eardrum

42. How Sound Waves Become Auditory Sensations
Cochlea – Where sound waves are transduced

43. How Sound Waves Become Auditory Sensations
Basilar membrane – Thin strip of tissue sensitive to vibrations
Cochlea

44. How Sound Waves Become Auditory Sensations
Auditory nerve – Neural pathway connecting the ear and the brain

45. In which area of the brain are auditory signals processed???
Review from Chapter 3!!!
In which area of the brain are auditory signals processed???

46. Answer:
Auditory cortex – Portion of the temporal lobe that processes sounds.

48. ANSWERS (a) outer ear (pinna) (b) ear canal (c) eardrum
(d) hammer, anvil, and stirrup   
(e) cochlea   
(f) auditory nerve

49. The Psychology of…
Pitch – Sensory characteristic of sound produced by the frequency of the sound wave.
Loudness – Sensory characteristic of sound produced by the amplitude (intensity) of the sound wave.
Timbre – Quality of a sound wave that derives from the wave’s complexity.
Video Clip

50. Hearing Loss Conduction Deafness –
An inability to hear resulting from damage to structures of the middle or inner ear.

51. Hearing Loss Nerve Deafness –
An inability to hear that is linked to a deficit in the body’s ability to transmit impulses from the cochlea to the brain, usually involving the auditory nerve.

53. The Senses: Smell, Taste, & Touch

54. Position and Movement
Vestibular sense – Sense of body orientation with respect to gravity.
Tells us how our bodies are positioned.
Movement and motion.
3 semicircular canals

55. Position and Movement
Kinesthetic sense – Sense of body position and movement of body parts relative to each other.
Makes you aware when you are crossing your legs.
Provides constant sensory feedback.

56. Olfaction Sense of smell.
Smell can influence mood, memory, emotions, mate choice, and the endocrine system (hormones).

57. Olfaction
Olfactory bulbs – Brain sites of olfactory processing.

58. Olfaction

59. Taste Gustation – The sense of taste.
Taste buds – Receptors for taste (primarily on the upper side of the tongue)

60. Taste Receptors
Sweet
Salty
Sour
Bitter
Umami
Savory sensation

61. TASTE & SMELL
Our sense of smell is responsible for about 80% of what we taste.
All other flavors that we experience come from smell. This is why, when we have a cold, most foods seem bland or tasteless.
Our sense of smell becomes stronger when we are hungry.

62. The Skin Senses
Touch
Warmth
Cold
Texture
Pain

63. Review from Chapter 3!!!
Sensory information related to the skin senses is processed within which part of the brain???

64. Answer:
SOMATOSENSORY CORTEX

65. Pain Gate-control theory
An explanation for pain control that proposes we have a neural “gate” that can, under circumstances, block incoming pain signals.

66. Pain Placebos – Substances that appear to be drugs but are not.
Placebo effect – A response to a placebo caused by subjects’ belief that they are taking real drugs.

67. What is the Relationship Between Perception and Sensation?
Perception brings meaning to sensation, so perception produces an interpretation of the external world, not a perfect representation of it.

68. Perception and Sensation?
Percept – Meaningful product of a perception.
What we perceive.

69. The Machinery of Perceptual Processing
Feature detectors – Cells in the cortex that specialize in extracting certain features of a stimulus.

70. The Machinery of Perceptual Processing
Binding problem – A major unsolved mystery in cognitive psychology, concerning the physical processes used by the brain to combine many aspects of sensation to a single percept.

71. Bottom-Up and Top-Down Processing
Bottom-up processing – Analysis that emphasizes characteristics of the stimulus, rather than internal concepts (stimulus-driven processing).
Top-down processing – Emphasizes perceiver's expectations, memories, and other cognitive factors (conceptually-driven processing).

72. Perceptual Constancy
Ability to recognize the same object under different conditions, such as changes in illumination, distance, or location.
Size
Shape
Color

74. ILLUSIONS
An incorrect experience of a stimulus pattern, shared by others in the same perceptual environment.
Muller-Lyer Illusion

75. Ponzo Illusion

76. Muller-Lyer Illusion

77. Ambiguous Figures
Images that are capable of more than one interpretation.

78.             Gestalt Psychology                            
The whole is greater than the sum of its parts.

79. The Gestalt Approach
Gestalt psychology – An approach to psychology that seeks to explain how we perceive overall patterns.
Figure – Part of a pattern that commands attention.
Ground – Part of a pattern that does not command attention; the background.

80. The Gestalt Approach
Closure – Tendency to fill in gaps in figures and see incomplete figures as complete.

81. The Gestalt Laws of Perceptual Grouping
Similarity
Proximity
Continuity
Common fate
Prägnanz

82. The Gestalt Approach
Similarity – we tend to group similar objects together in our perceptions.

83. The Gestalt Approach
Proximity – we tend to group objects together when they are near each other.

84. The Gestalt Approach
Continuity – we prefer perceptions of connected and continuous figures to disconnected and disjointed ones.

85. The Gestalt Approach
Common Fate – we tend to group similar objects together that share a common motion or destination.

86. The Gestalt Approach A BIRD IN THE THE HAND Law of Prägnanz
The simplest organization, requiring the least amount of cognitive effort, will emerge as the figure. A
BIRD
IN THE
THE HAND

87. Depth Perception Visual Cliff Experiment
Develops around months of age

88. Depth Perception
Binocular cues – information taken in by both eyes that aids in depth perception, including convergence and retinal disparity.

89. Depth Perception
Monocular Cues – information about depth that relies on just one eye; includes relative size, light and shadow, interposition, relative motion, and atmospheric perspective.

90. Theoretical Explanations for Perception
Learning-based inference – View that perception is primarily shaped by learning, rather than innate factors.
Perceptual set – Readiness to detect a particular stimulus in a given context.

91. End of Chapter 4