1. Sensation & Perception Chapter 4 Psyc103~019 Jen Wright TR 12:30-1:15

2. perception Perception seems like the sort of thing that should be straightforward… –There is a physical world out there to be perceived –We need to be able to perceive it in order to survive But, in truth, perception is a funny thing… –We often fail to see what’s right in front of us –And we often see things that aren’t actually there

6. what is perception? How do we explain this? –To explain this we need to understand the nature of perception. Let’s start by identifying the difference between sensation and perception. Sensation – simple awareness due to the stimulation of a sensory organ. –A) True –B) False

7. Sensation involves transduction What is transduction? –A) physical signals turned into neural signals –B) neural signals turned into physical signals –C) sent from sensory organs to the central nervous system –D) A & C

8. Perception – the organization, identification, interpretation of sensation (transduced signals) in order to form a mental representation. Two different theories of perception: 1.Bottom-up processing –Physical features of stimulus alone drive perception 2.Top-down processing –Knowledge, expectations, desires, and thoughts of perceiver drive perception

9. bottom-up

10. =

11. top-down Thoughts, beliefs, desires, expectations, past experiences

12. ?

13. Research suggests that: –A) we build mental representations that accurately (and impartially) reflect the world. –B) we don’t build mental representations that accurately (and impartially) reflect the world.  Rather, our interpretation goes into the very construction of the mental representation itself.

14. The goal of perception is not to create a replica of the experienced world in our heads. Instead, perception is a dynamic and ongoing construction project –short-lived models of the external world are being continuously built –designed for the current perceptually guided tasks of the viewer What we perceive depends as much on our goals, expectations, and beliefs as it does on transduction. –A) True –B) False

15. perceptual constancy –A) sensory signals change  perception of the object does not change –B) sensory signals change  perception of the object changes Our perception is altered based not on changes in sensory stimuli but based on beliefs.

16. top down processing (“seeing as”) Attention matters  Shift in focus results in shift in perception.

17. Context matters Image 1 Image 2 Image 3 Image 4

18. Image #1 –A) 13 –B) B Image #2 –A) man playing saxophone –B) woman’s face

19. Image #3 –A) “liar” –B) man’s face Image #4 –A) donkey –B) seal

20. Environment (culture) matters Which line looks longer? ABA B T/F: The experience of this illusion is universal to all human beings. False! Members of Zulu and San do not experience the same illusions.

21. Which of the following faces looks messed up? Both right-hand faces have eyes and mouth that are upside down. –So, why does the bottom face look so much worse? Because of our –Experience –Expectations

22. perceptual expectations

25. The conclusion is that: A) our sensory systems are misreporting information about the real world to our brains. B) our brains are “interpreting” (rather than straightforwardly “translating”) incoming sensory information. C) neither

26. Top down processing occurs for all forms of sensory perception –Perception of heat/cold –Perception of weight –Perception of tastes, sounds And even in our (higher-order) social perception

28. social perception Symmetrical, well-balanced faces are perceived as more attractive. They are also perceived as more intelligent, funny, interesting, desirable, competent, sexual, successful…. –“beautiful is good” phenomenon

29. social cognition The processes by which we use available sensory information to form impressions of other people, to classify them according to their attributes. What determines what classifications we use? Purposes of the perceiver –We use concepts to determine how people will affect the pursuit of our goals. Accessibility in memory –Experience may make some classifications more accessible than others. Availability of stereotypes –fixed set of characteristics we tend to attribute to group members. Social context –The social context strongly influences the ways we label people and their behavior.

30. The power of social context to influence perception. Violinist in DC Metro Station –Joshua Bell Considered one of the best violinists in the world –Played a violin worth $3.5 million –People pay over $100/seat to see him play He collected only $32 from over 1000 people – http://www.youtube.com/watch?v=hnOPu0_YWhwhttp://www.youtube.com/watch?v=hnOPu0_YWhw

31. social categories Stereotypes as concepts – top-down activation Shooting of Amadou Diallo –Pure accident? –Outright racism? Automatic influence of racial stereotype? –Police saw him as “armed and dangerous”

32. Guns–Tools Task (Payne, 2001) Faces prime social categories. Participants must rapidly choose gun or tool during the visual mask. Identify quickly flashed objects, half tools and half guns. Half were preceded by a black face, half by a white face. 200ms 300ms Decide gun or tool

33. 200ms Guns–Tools Task (Payne, 2001) 300ms Prime Decide gun or tool African American prime causes significant increase in mistakenly reporting “gun” when tool was shown

34. other studies People primed with elderly stereotype will perceive hills to be steeper and distances longer. People primed with stereotype of obesity perceived people to be less intelligent, more lazy. Priming with gender influences perception of artistic pieces and writing. Priming of stereotypes facilitate specific interpretations of behavior.

35. People can be primed to act consistently with stereotypes that don’t otherwise apply –A) True –B) False People can be primed to see things that are consistent with their stereotypes even when they don’t exit –A) True –B) False

38. Change blindness – the phenomenon of a person viewing a visual scene and failing to detect large changes in the scene. So, what is going on? Could be that our (short-term) visual memory is relatively impoverished. –we only form a representation of that which we are actually paying attention to. Could be that our visual memory is richer than that of which we are conscious.

39. What do we really see? http://viscog.beckman.uiuc.edu/flashmovie/15.php Video clip: BB counting experiment Video clip: different person http://viscog.beckman.uiuc.edu/djs_lab/demos.html Gradual changes to scenes http://nivea.psycho.univ- paris5.fr/Mudsplash/Nature_Supp_Inf/Movies/Movie_List. htmlhttp://nivea.psycho.univ- paris5.fr/Mudsplash/Nature_Supp_Inf/Movies/Movie_List. html http://www.psych.ubc.ca/~rensink/flicker/download

41. Exam 01 Version 1 Version 2 Version 3 17323 20265 Descriptive Statistics NMinimumMaximumMean Std. Deviation didn't attend5437.0095.0076.388912.23306 attended3260.5096.0078.343810.21656