Perception

1. Perception How we organize and interpret sensory information

2. Inattentional Blindness • When focusing on one thing, we often miss or ignore other stimuli (no matter how exaggerated or crazy the stimuli may be… for example the gorilla in the basketball game).

3. Selective attention - we can only focus awareness on a limited part of what we are sensing. Cocktail party effect – type of selective attention in which you can attend to only one voice at a time Cell phones and driving? Listening to music and studying?

4. Visual Capture • The tendency for vision to dominate your senses. • At an IMAX movie, it feels like you are moving because it looks like you are moving. Your vision dominates over your vestibular system.

5. Parallel processing – processing many things at once • Man who mistook his wife for a hat – could see form but not the big picture • Colorblindness with functional cones • Motion blindness • Blindsight

6. Perceiving Images The first step in perceiving an image is determining the figure and ground.

7. The Gestalt Principles

8. Gestalt and the Urge to Organize

9. Gestalt and the blind spot

10. Other gestalt principles

11. More gestalt

12. And more gestalt

13. Depth Perception (seeing in 3D) • Binocular cues – require both eyes • Retinal disparity – cue for relative distance of different objects (greater the disparity, the closer the object) • Convergence – extent to which eyes converge inward when looking at something (greater inward strain, the closer it is)

14. Depth Perception (cont’d) • Monocular cues (available to each eye separately) • Relative size – assuming two objects are the same size, the one casting a smaller retinal image is farther away • Interposition – object partially blocking view of another perceived as closer • Relative clarity – hazy objects perceived as farther away than sharp, clear objects • Texture gradient – gradual change from coarse, distinct texture to a fine, indistinct texture signals increasing distance

15. Depth Perception (cont’d) • Monocular cues (cont’d) • Relative motion (motion parallax) – as we move, objects that are stable appear to move. The nearer the object, the faster it appears to move. Objects beyond fixation appear to move with you. • Linear perspective – parallel lines appear to converge with distance. • Light and shadow – Nearby objects reflect more light on our eyes. Dimmer ones seem farther away. (Janus’ mask… assume light comes from above, so location of shadow indicates whether objects are concave or convex)

16. Motion PerceptionHow does the brain recognize an object is moving? How does it interpret the direction of movement? Brain interprets shrinking objects as receding and enlarging objects as approaching

17. Stroboscopic Effectthe perception of motion produced by a rapid succession of slightly varying images (animation, movies)

18. Phi phenomenonan illusion created when two or more adjacent lights blink on and off in succession, creating the perception of movement (lighted signs, illusions)

19. Motion Perception • Objects that are farther away appear to be moving more slowly. Think of a plane in the sky or a truck in the distance

20. Perceptual Constancy - the ability to perceive an object is the same even as the illumination and retinal image changes.Shape Constancy – perception that shape of an object doesn’t change just because image on the retina does.

21. How many right angles do you see?

22. Perceptual Constancy • Size constancy – perception that an object’s size remain the same even as the retinal image changes. • Color Constancy – the perception that familiar objects have a consistent color, even if changing illuminations alter the wavelength reflected.

23. What color are the squares indicated by arrows? Don’t believe me….? Watch this!

25. Perceptual Constancy Lightness constancy – the perception that familiar objects have a constant lightness, even while illumination varies.

27. Size-distance relationship When other monocular cues tell us an image is further away, it actually appears larger.

29. Moon illusion • Imagine you are outside on a clear night in which there are no clouds and that is a bright full moon. Pretend that you are going to pick up one of the following objects that when held at arm’s length just covers up the moon.

30. Moon Illusion Objects Imagine the moon is straight overhead. BB Pea Dime Penny Nickel Quarter Golf ball Baseball Softball Small Salad Plate Large Salad Plate Frisbee Basketball Beach ball

31. Moon IllusionNow imagine the horizon moon. BB Pea Dime Penny Nickel Quarter Golf ball Baseball Softball Small Salad Plate Large Salad Plate Frisbee Basketball Beach ball

32. Moon Illusion What object do you need? A pea! For both the overhead and horizon moon.

33. Muller-Lyon IllusionWhich is longer?

34. Muller-Lyon Illusion

35. Perceptual Adaptation What happens if you wear goggles that distort your world? Could you shake hands? Catch a ball? Let’s try!!

36. Perceptual Set – like a mental predisposition Looking at either the left or the right-hand image first is likely to cloud your perspective of the center, ambiguous figure.

37. Perceptual Set Examples • Punctuate the following so it makes sense: • TIME FLIES I CANT THEYRE TOO FAST • Read the following words out loud as they appear: • MacDonald • MacHenry • MacMurray • Machinery • Now let’s try some more… 

38. Unscramble in order. List B List A LULB NORC CALEM NOONI BAZER MATOOT SEUMO PREPPE NUKKS TEBE EAP EAP

39. In the next slide you will see a picture of two people. Name the person standing on the left (slightly behind the other person).

40. Context Effects

41. Who was it? • Let’s take another look…

42. Extrasensory Perception • Telepathy – mind reading • Clairvoyance – perceiving remote events • Precognition – Knowing things before they happen • Telekinesis (psychokinesis) – moving objects with one’s mind (not technically ESP)