1. Chapter 5: Sensation Unit #3, Entry #1

2. Sensation & Perception
How do we construct our representations of the external world?
To represent the world, we must detect physical energy (a stimulus) from the environment and convert it into neural signals. This is a process called sensation.
 5 senses: sight, sound, touch, taste, smell
When we select, organize, and interpret our sensations, the process is called perception.
OBJECTIVE 1| Contrast sensation and perception, and explain the difference between bottom-up and top-down processing.

3. Senses are nature’s gift that suit an organism’s needs.
Sensing the World
Senses are nature’s gift that suit an organism’s needs.
A frog feeds on flying insects; a male silkworm moth is sensitive to female sex-attractant odor; and we as human beings are sensitive to sound frequencies that represent the range of human voice.

4. Exploring the Senses
What stimuli cross our threshold for conscious awareness?
Could we be influenced by stimuli too weak (subliminal) to be perceived?
Why are we unaware of unchanging stimuli, like a band-aid on our skin?

5. Psychophysics
A study of the relationship between physical characteristics of stimuli and our psychological experience with them.
Physical World
Psychological World
Light
Brightness
Sound
Volume
Pressure
Weight
Sugar
Sweet
-What stimuli can we detect?
-At what intensity?
-How sensitive are we to changing stimuli?

6. Several Concepts influence our sensation and perception:
1.) Absolute Threshold: the weakest/smallest amount of a stimulus that can be sensed.
ex: can you taste a single drop of lemon juice in a bottle of water?
Ex2 :
-Is different for everyone.

7. Detection Absolute Threshold Intensity No No No Yes Yes Detected
Observer’s Response
Detected
Tell when you (the observer) detect the light.

8. Several Concepts influence our sensation and perception:
2.) Difference Threshold: The smallest amount of a difference that can be detected between two stimuli
Ex: can you tell the difference between 2 orange paint chips that are only a shade different in color?
Ex 2:

9. Difference Threshold: also called just noticeable difference (JND).
Yes
Observer’s Response
Tell when you (observer) detect a difference in the light.

10. Several Concepts influence our sensation and perception:
3.) Subliminal Threshold: When stimuli are below one’s absolute threshold for conscious awareness.
Ex:

11. Several concepts influence our sensation and perception:
4.) Signal Detection Theory: belief that we distinguish and focus on different sensory stimuli based on their strengths, the setting we are in, our physical state, mood, and attitude.
Ex: do you notice when someone walks into the room? When a teacher calls your name?
Ex 2:
*We focus on what we consider important!

12. Signal Detection Theory (SDT)
Predicts how and when we detect the presence of a faint stimulus (signal) amid background noise (other stimulation).
Detection depends on:
Person’s experience
Expectations
Motivation
Level of fatigue
Carol Lee/ Tony Stone Images 12

13. Several concepts influence our sensation and perception:
5.) Sensory Adaptation: Process by which we adapt to the sensory stimuli in our environment.
Ex: walk into dark theater, can’t see at first. Eyes adjust, then you can see
Ex 2:
Put a band aid on your arm and after awhile
you don’t sense it.

14. Sensory Adaptation
Diminished sensitivity as a consequence of constant stimulation.
OBJECTIVE 3| Describe sensory adaptation, and explain how we benefit from being unaware of changing stimuli.
Put a band aid on your arm and after awhile
you don’t sense it.

15. Subliminal Threshold
Subliminal Threshold: When stimuli are below one’s absolute threshold for conscious awareness.
Kurt Scholz/ Superstock

16. Subliminal Threshold Can we unconsciously sense subliminal stimuli?
Without our conscious awareness of the stimuli, can they have suggestive powers and influence our thoughts and/or behaviors?

17. Subliminal Threshold Can we unconsciously sense subliminal stimuli?
The answer to a certain extent seems to be yes!
Sometimes we feel what we do not know and cannot describe = intuition
Subliminal stimuli may evoke a feeling, though not a conscious awareness of the stimulus
*MUCH OF OUR INFORMATION PROCESSING OCCURS AUTOMATICALLY, OUT OF SIGHT, OFF THE RADAR SCREEN OF OUR CONSCIOUS MIND!

18. http://wtso. net/movie/346-1214%20%20New%20Kids%20on%20the%20Blecch
Subliminal Threshold
Without our conscious awareness of the stimuli, can they have suggestive powers and influence our thoughts and/or behaviors?
Subliminal messaging in advertising, music, self-help tapes, etc.
Yes, it is possible for them to have a subtle, fleeting effect.
But there is no evidence of a strong or lasting influence on one’s behavior.
Self-help tape study 1991
We are vulnerable to placebo effect- our expectations or what we are told should happen.

19. Subliminal Threshold Priming:
The activation, often unconsciously, of certain associations, thus predisposing a person’s memory, perception, or reponse.
*those who saw pictures of animals were influenced to see the horse

20. The Eye
OBJECTIVE 5| Describe the major structure of the eye, and explain how they guide the incoming ray of light toward the eye’s receptor cells.

21. Parts of the eye
Cornea: Transparent tissue where light enters the eye.
Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light.
Lens: Focuses the light rays on the retina.
Retina: Contains sensory receptors that process visual information and sends it to the brain.

22. The Lens
Lens: Transparent structure behind the pupil that changes shape to focus images on the retina.
Accommodation: The process by which the eye’s lens changes shape to help focus near or far objects on the retina.

23. The Lens
Nearsightedness: A condition in which nearby objects are seen more clearly than distant objects.
Farsightedness: A condition in which faraway objects are seen more clearly than near objects.

24. Retina
Retina: The light-sensitive inner surface of the eye, containing receptor rods and cones in addition to layers of other neurons (bipolar, ganglion cells) that process visual information.
OBJECTIVE 6| Contrast the two types of receptor cells in the retina, and describe the retina’s reaction to light.

25. Optic Nerve, Blind Spot & Fovea
Optic nerve: Carries neural impulses from the eye to the brain. Blind Spot: Point where the optic nerve leaves the eye because there are no receptor cells located there. This creates a blind spot. Fovea: Central point in the retina around which the eye’s cones cluster.

26. Photoreceptors
E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969

27. Bipolar & Ganglion Cells
Bipolar cells receive messages from photoreceptors and transmit them to ganglion cells, which are for the optic nerve.

28. Visual Information Processing
Optic nerves connect to the thalamus in the middle of the brain, and the thalamus connects to the visual cortex.
OBJECTIVE 7| Discuss the different levels of processing that occur as information travels from the retina to the brain’s cortex.

29. Color Constancy
Color of an object remains the same under different illuminations. However, when context changes the color of an object may look different.
OBJECTIVE 10| Explain the importance of color constancy.
R. Beau Lotto at University College, London

30. HEARING
Entry #3
Pages 85-88

31. How do you hear?
Sound travels through the air in waves and creates vibrations
(Ever felt your clothes vibrating from loud music?)
Each vibration is called a cycle or wavelength

32. Pitch: how high or low a sound is
Shorter wavelengths vibrate more frequently = create a higher pitch
Longer wavelengths vibrate fewer times = create a lower pitch

33. Pitch
The greater the number of cycles per second, the higher the pitch.

34. Loudness Amplitude – height
The higher the amplitude of a wave, the louder the sound.
Decibel – A unit expressing the loudness of a sound. Abbreviated dB.

35. Loudness of Sound
Richard Kaylin/ Stone/ Getty Images
120dB
70dB

36. Localization of Sounds
Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.
OBJECTIVE 14| Describe how we pinpoint sounds.

37. Hearing Loss
Conduction Hearing Loss: Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.
Sensorineural Hearing Loss: Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness.
OBJECTIVE 15| Contrast two types of hearing loss, and describe some of their causes.

38. Other Important Senses
The sense of touch is a mix of four distinct skin senses—pressure, warmth, cold, and pain.
OBJECTIVE 17| Describe the sense of touch. “Touch is both the alpha and omega of affection” (James, 1890).
Bruce Ayers/ Stone/ Getty Images

39. Skin Senses
Only pressure has identifiable receptors. All other skin sensations are variations of pressure, warmth, cold and pain.
Pressure
Vibration
Vibration
Burning hot
Cold, warmth and pain

40. Ashley Blocker (right) feels neither pain
Pain tells the body that something has gone wrong. Usually pain results from damage to the skin and other tissues. A rare disease exists in which the afflicted person feels no pain.
How we experience pain depends on:
-our experiences and attention
-our physiology
-our cultural surroundings
=Biopsychosocial explanation
OBJECTIVE 18| State the purpose of pain, and describe the biopsychosocial perspective on pain.
Ashley Blocker (right) feels neither pain
nor extreme hot or cold.

41. Biopsychosocial Influences

42. What Causes Pain?
Unlike vision, the pain system is not located in a simple nueral cord running from a sensing device to a definable brain area. And there is no one type of stimulus that triggers pain (as light triggers vision) and there are no special pain receptors (like rods and cones for vision)

43. What Causes Pain? Gate Control Theory:
The spine contains a neurological “gate” that either blocks pain signals from being sent to the brain, or allows them to pass to the brain.
Gate is opened by activity of pain signals
Gate can be closed by stronger activity messages from other areas of the body (rubbing near the area of pain, accupuncture)
or by information from the brain (being distracted from something in environment, presence of endorphines

44. Gate-Control Theory
One way to treat chronic pain is to stimulate it through massage by electrical stimulation or acupuncture. Rubbing causes competitive stimulation to pain thus reduces its effect.

45. Pain Control
Pain can be controlled by a number of therapies including, drugs, surgery, acupuncture, exercise, hypnosis, and even thought distraction.
Burn victims can be distracted by allowing them to engage in illusory virtual reality. Their brain scans show differences in pain perceptions.
Todd Richards and Aric Vills, U.W.
©Hunter Hoffman,

46. Pain Control
Burn victims can be distracted by allowing them to engage in illusory virtual reality. Their brain scans show differences in pain perceptions.
Lamaze method of childbirth combines relaxation (through deep breathing and muscle relaxation), counterstimulation (through gentle message), and distraction (through focusing attention on a pleasant object or picture)