1. Perception How do we define it?
How we recognize and interpret stimuli
Top down processing…
Remember, expectations and previous experiences play an influential role…

6. Selective Attention
Our senses can take in approximately 11,000 bits of information at a time
BUT…
We can only focus on one thing at a time…

7. Neisser’s Basketball Study
Inattentional Blindness
Focusing on one stimulus prevents us from noticing others
The dancing gorilla (bear)
Texting and driving!

8. 2 readers, one listener…. Cocktail Party Effect
Can listen to only one voice at a time
Can notice gender
Can detect name

9. Just how much do we notice?
Change blindness
We fail to notice changes in our environment (when we are focusing on something else)

10. Pop Outs!
Striking distinctions grab our attention

11. Perceptual Illusions
Mislead us by playing on the way we organize and interpret our sensations
(challenges our schema!)
Reveal how we normally organize our sensations (thus clues to mechanisms of perception)
Visual Capture: Vision is our dominant sense (effects how we perceive our other senses)
McGurk Effect (Youtube/edu)

18. Perceptual Organization
Visual Agnosia
See all parts of an image, but not the whole, (or meaning)

19. Gestalt (“form”) “The whole is greater than the sum of its parts”
We tend to see, or group images as a whole, not as individual or isolated parts
A natural, or innate form of perception

20. Gestalt: (How we group objects)
Figure and ground (sometimes can be reversible)

21. Gestalt
Proximity

22. Gestalt
Similarity

23. Gestalt
Continuity

24. Gestalt
Closure

25. Depth Perception Binocular Cues (interplay of two eyes)
Retinal Disparity: each eye sees object from slightly different angle (brain computes difference in vision to judge depth)
Convergence: eyes move together as item gets closer (brain detects convergence of eyes as measure of depth)
The Finger Sausage!

26. Depth Perception
Monocular Cues
Relative Size

27. Monocular Cues
Linear perspective

28. Monocular Cues
Texture gradient

29. Monocular Cues
Interposition

30. Monocular Cues
Relative Height

31. Monocular Cues
Relative Clarity

32. Monocular Cues
Relative Motion (The faster it moves…)

33. Monocular Cues
Light and Shadow

34. Motion Perception Phi Phenomenon Troxler Effect
With loss of sight- motion is usually first to be restored

35. Perceptual Constancy
Perceiving an object as unchanging despite a change in stimulus
Key factors: Experience, Expectation (Rules of perception)
Size Constancy:
As stimulus changes, we literally see changing size, but we know size has not changed due to experience and context of objects surroundings

36. Size Constancy http://www. eruptingmind

37. Shape Constancy
We know shape is constant even though our angle and thus vision of object changes

38. Lightness (Color) Constancy
We see objects as having consistent color, even as changing conditions alter the wavelength reflecting off the object.

39. Perceptual Set “To believe it is to see it” A mental predisposition
Experiences give us a perceptual set, or assumptions that influence how or what we see…

40. Context Effect
The context in which a stimulus appears affects how we perceive it…
“…eel is on the wagon.”
“…eel is on the orange.”

41. Sensory Deprivation / Restored Vision
Adults with vision for first time (cataract surgery)
Have Sense of colors, detect figure from ground
No depth perception, no perceptual constancy (cortical cells not developed)
*Much of perception is learned during critical period in early development

42. Perceptual Adaptation
Our perception can adapt to change in stimuli, environment
Inverted goggles!!

43. Perceptual Constancy pages 250-262
Shape constancy
Size constancy
Light constancy

44. Sensory Deprivation and Restored Vision
Perceptual Adaptation
Perceptual Set
Context Effects