Sensation and Perception

1. Sensation and Perception

2. Our Essential Questions!  • How do sensations and perceptions differ? • How do the senses transform information into brain messages? • What is the nature of attention?

3. Grab a scrap sheet of paper • Write down your definition of • sensation • perception

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

5. Perception The process of integrating, organizing and interpreting sensations.

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

8. Top-Down Processing • Top-Down Processing: • expectations and experiences influence how we interpret incoming sensory information

9. The Major Senses • 7 major senses • Vision (most studied) • Hearing • Touch • Smell • Taste • Vestibular • Kinesthetic

10. The Riddle of Separate Sensations • Sense receptors • specialized cells unique to each sense organ that respond to a particular form of sensory stimulation

11. Sensory Receptors – An Example • When you bite into a crisp apple, you hear the crunch, you taste the sweetness, you feel the smooth skin, you see the red, and you smell the aroma.

12. Receptor Cells • Each of the five senses is specifically coded to only take in one type of stimulus, whether it be light waves, sound waves, smell, taste, or touch.

13. What Does That Mean? • Turn to your neighbor and tell them what sensation means. • What is with those blasted receptor cells as well… explain what they do

14. Sensory Receptors • Specialized cells unique to each sense organ that respond to a particular form of sensory stimulation.

15. Sensory Receptors: Example • A combination of your senses. When you bite into a crisp apple, you hear the crunch, you taste the sweetness, you feel the smooth skin, you see the red, and you smell the aroma.

16. Sensation & Perception Processes

17. Principles of Sensation • Transduction • Absolute threshold • Difference threshold • Sensory adaptation

18. Transduction • The process by which a form of physical energy is converted into a coded neural signal that can be processed by the nervous system.

19. What Does That Mean? • Turn to your neighbor and tell them what you think perception means… • What is the difference between sensation and perception?

20. What is a Threshold?

21. Threshold • An edge or a boundary • Walking into the room – on one side you are in the room on the other you are outside of the room

22. Subliminal Messages?

23. Absolute Threshold • The smallest possible strength of a stimulus that can be detected half the time.

24. Absolute or Detection Threshold • The minimum intensity of energy required to produce sensation in a receptor cell • Taste: 1 gram of table salt in 500 liters of water

25. Touch: The wing of a bee falling on your cheek from a height of 1 centimeter • Hearing: The tick of a watch from 6 meters away

26. Vision: A candle flame on a clear night, 30 miles away

27. Absolute Threshold Example (1) • Taste: 1 gram of table salt in 500 liters of water – the minimum needed to taste something

28. Absolute Threshold (2) • Vision: A candle flame on a clear night, 30 miles away – the minimum needed to see it. Doesn’t mean that you can make out what it is

29. Just Noticeable Difference Threshold • The minimum difference that a person can detect between two stimuli 50% of the time.

30. Weber’s Law The greater the magnitude of the stimulus, the larger the difference must be in order to be noticed

31. Examples When you can detect the difference in volume of music When you can detect the difference in pressure on your arm

32. Weber’s Law Example If you are carrying 20 lbs. and add 5 lbs., it’s noticeable. If you are carrying 100 pounds and add 5 pounds, it may not be noticeable. You need to add 10 lbs. to 100 pounds to make it noticeable.

33. Sensory Adaptation • When exposed to a stimuli over a period of time there will be a diminished sensitivity to it • If a stimulus is constant and unchanging, eventually a person may fail to respond to it

34. Example of Sensory Adaptation • A hot tub – after a certain period of time no longer seems as hot

35. The Nature of Attention • Where does attention come into play here?

36. Hypothetical Situation • What would happen if we had no filter between sensation and perception?” • Hallway example

37. Sensory Overload • Overstimulation of the senses

38. Selective hearing • Do you think it exists?

39. Selective Attention • Focusing conscious awareness on a particular stimulus (sense) to the exclusion of others

40. Selective Attention Examples • Walking down the hallway – all 5 senses are firing. What grabs your attention?

41. Let’s write! • How do sensations and perceptions differ? • How do the senses transform information into brain messages? • What is attention? How much control do we have over our attention?

42. Time to get creative! • With your partner, create a poster depicting all 5 of the following: • Sensation • Perception • transduction • Selective Attention • Absolute sensory thresholds • Difference threshold