Sensation & Perception

1. …. Sensation & Perception

2. What we’ll sense and perceive…in this chapter: • Sense: • especially vision and hearing • smell, taste, touch, pain, and awareness of body position • How do the sense organs and nervous system handle incoming sensory information? • How does the brain turn sensory information into perceptions? • Why is our style of creating perceptions better at perceiving the real world than at decoding tricky optical illusions?

3. Do you see a painting or a 3D bottle? What’s on the bottle? Kids see eight to ten dolphins. Define sensation and perception. Why do you think kids see something different than adults? In your answer use the following terms: Top-down processing

5. From Sensory Organs to the Brain The process of sensation can be seen as three steps:

6. Sensation vs. Perception Sensation Perception “The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.” “The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.” The brain receives input from the sensory organs. The brain makes sense out of the input from sensory organs.

7. Read this sentence carefully and you will note some odd things about it. The marks you interpreted as the word is in the top line are exactly the same marks you interpreted as 15 in the phone number. Can you find the other examples of the same marks being interpreted two ways? Here is where sensation and perception come together. Sensation involves moving the image from the book to your brain, a bottom-up process of gathering environmental information through the senses. Perception involves knowing what to make of the individual marks in the sentence. This top-down interpretation relies on your experiences with, and expectations about, language.

8. The Flowering of Love . . . • What do you see? • Our sensory and perceptual processes work together to help us sort out the complex images.

9. Top-Down Processing • Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Our experience and expectations enable us to immediately perceive the scrambled letters as meaningful words and sentences.

10. Making sense of the world Top-down processing: using models, ideas, and expectations to interpret sensory information What am I seeing? Bottom-up processing: taking sensory information and then assembling and integrating it Is that something I’ve seen before?

11. Sensation • How we detect physical energy in the environment & encode it as neural signals.. • Bottom up processing: Analysis that begins with the sense receptors and works up to the brain’s integration of sensory information.

12. Sensation • How we detect physical energy in the environment & encode it as neural signals.. • Bottom up processing: Analysis that begins with the sense receptors and works up to the brain’s integration of sensory information.

13. Perception • How we select, organize, and interpret information. • Top down processing: Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

14. Perception • How we select, organize, and interpret information. • Top down processing: Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

15. Absolute Threshold • Sense receptors are remarkably sensitive. • Absolute Threshold – is the weakest amount of a stimulus that a person can reliably detect. • Will differ person to person • Subliminal – below one’s absolute threshold for conscious awareness.

16. Do I smell it or not? When stimuli are detectable less than 50 percent of the time, they are ""subliminal."" Absolute threshold is the intensity at which we can detect a stimulus half the time.

17. James Vicary – “subliminal advertising” • 1957 book The Hidden Persuaders by Vance Packard. • Ft. Lee NJ movie theater (1957) • Throughout the movie Picnic he flashed • “Drink Coca-Cola” and “Hungry? Eat Popcorn” • Sales increased 18% for Coke & 57% for popcorn

18. The legend • Vicary lied about his results • When asked to replicate his experiment, he produced no significant increase in popcorn or Coke sales. • Eventually he confessed that he falsified his experiments. Phenomenon stayed in pop culture. • 1973 the book Subliminal Seduction claimed that subliminal techiques were in wide use in advertising. • Federal Communications Commission to hold hearings and to declare subliminal advertising "contrary to the public interest" because it involved "intentional deception" of the public.

19. Priming the Brain • An imperceptible brief stimulus triggers a weak reaction in the brain (shown by scans). • Its only when the stimulus triggers synchronized activity in several brain regions does the stimulus reach consciousness. • DUAL TRACK MIND . . . . Much of our processing occurs out of our conscious mind.

20. Research • People gazed at the center of a screen and were flashed a nude photo of a person on one side and a scrambled version of the photo on the other side. The images were immediately masked by a checkerboard, the volunteers saw nothing but flashes of color and were unable to guess where the nude had appeared. • Researchers flashed a geometric figure to one side or the other, followed by the masking stimulus, and asked the volunteers to give the figure’s angle.

21. Research • Straight men were more accurate when the geometric figure appeared where a nude woman had been. • Gay men & straight women were more accurate when the figure appeared where nude MAN had been. • Participants attention was unconsciously drawn to the image in a way that reflected their sexual orientation. • We can evaluate a stimulus even when we are not aware of it; and even when we are unaware of our evaluation

22. Subliminal Messages & Backward Masking • Consider what would happen if parents sat down and listened to backwards rock music expecting to find references to drugs, sex and the devil. • Because there is great ambiguity in the recordings, they are likely to find what they are looking for. This does not mean the messages are really there.

23. Subliminal Messages http://jeffmilner.com/backmasking.htm http://www.youtube.com/watch?v=7B-0V0jq0Fo&feature=player_embedded

24. Subliminal Messages & Backward Masking • Perception of messages in backwards recordings is largely governed by our expectations. • Example of Top Down Processing • Constructing perceptions drawing on our experiences and expectations • Perception is heavily influenced by one's belief system. We not only see what we want to see and hear what we want to hear, we see what we expect to see.

25. Research on subliminal messages • Subliminal messages are generally ineffective or quite limited in their influence. • A message recorded backwards is unintelligible when the record played forwards. It could not be understood even if it was played apart from the music. • A backmasked message superimposed on a musical passage would be itself masked by the music so that it would not readily be heard. • No research to indicate that subliminal stimulation produces major changes in behavior even if it were present. • http://www.ultimatetop10s.com/top-10-subliminal-messages-in-disney-animations/

27. http://www.snopes.com/disney/films/lionking.htm - add

30. The Little Mermaid.

34. Top-down processing by children uses different experiences and different models; they are likely to have seen more images of dolphins than images of a nude embrace. Adults also do more top-down processing, and are more likely to “see” objects that aren’t fully there. This shows that “seeing” involves the process of perception, not just the process of our eyes taking in information.

35. Sensation • How we detect physical energy in the environment & encode it as neural signals.. • Bottom up processing: Analysis that begins with the sense receptors and works up to the brain’s integration of sensory information.

36. Perception • How we select, organize, and interpret information. • Top down processing: Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

38. What’s Going On? • Our sensory and perceptual processes work together to help us sort out the complex images in the Bev Doolittle painting, “The Forest has Eyes”. Bottom-up processing enables our sensory system to detect the lines, angels and colors that form the horses, rider, and surroundings. Using top-down processing we consider the painting’s title, notice the apprehensive expressions, and then direct our attention to aspects of the painting that will give those observations meaning.

39. When Absolute Thresholds are not Absolute • Signal detection theory refers to whether or not we detect a stimulus, especially amidst background noise. • In other words, what are some things that influence whether or not we attend to something in our environment. (What influences FRANK!?) • predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) • assumes that there is no single absolute threshold • detection depends partly on person’s • experience • expectations • motivation • level of fatigue • Examples of situations where this may apply? • DISCUSS WITH PARTNER . . . LIST AS MANY AS YOU CAN!!

40. Sensation- Thresholds • Signal Detection Theory • predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) • assumes that there is no single absolute threshold • detection depends partly on person’s • experience • expectations • motivation • level of fatigue

41. Difference Threshold – Just Noticeable Difference • Applies to each of our senses: the minimal differences between two stimuli that people can reliably detect. • In turning down music your sister might say “I don’t hear any difference!” • You haven’t met her difference threshold.

42. The “Just Noticeable Difference” • Difference threshold refers to the minimum difference (in color, pitch, weight, temperature, etc) for a person to be able to detect the difference half the time. • Weber’s law refers to the principle that for two stimuli to be perceived as different, they must differ by a constant minimum percentage and not a constant amount (e.g. 1/100th of the weight, not 2 ounces).

43. Difference Threshold – just noticeable difference • In this computer-generated copy of the Twenty-third Psalm, each line of the typeface changes imperceptibly. How many lines are required for you to experience a just noticeable difference?

44. Sensory Adaptation • Process by which sensory systems adapt to constant stimuli by becoming less sensitive to them. • Wearing a new ring vs. being married for 50 yrs. • Water in a lake / tub

45. Counter-Rotating Spirals Illusion • http://dogfeathers.com/java/spirals.html • Feature Detectors – our brains have specialized groups of cells dedicated to the detection of specific stimulus features (length, slant, color, boundary) • HUBEL and WIESEL discovered these.

46. Perceptual Set Perceptual set is what we expect to see, which influences what we do see. Perceptual set is an example of top-down processing . Loch Ness monster or a tree branch? Flying saucers or clouds?

47. Perceptual Set :Look at the girl’s face:

48. Couple or Skull?

49. Perceptual set can be “primed.” Young woman Old woman

50. Ambiguous