1. Sensation & Perception
4/15/2017
Pop-Out Phenomenon
When a strikingly distinct stimulus, such as the only smiling face, draws our eye.
©1999 Prentice Hall

2. Sensation & Perception
4/15/2017
Perceptual Sets
The tendency for our perceptions to be influenced by expectations or preconceptions.
A mental predisposition that greatly influences what we see.
Devoted fans to science fiction are more likely to see UFO’s
We may fail to notice writing and printing errors.
Have also found that emotion, motivation and culture can influence our perception.
Is this the letter B or the number 13?
©1999 Prentice Hall

3. The cat sat on the map and licked its whiskers.
Sensation & Perception
4/15/2017
The cat sat on the map and licked its whiskers.
©1999 Prentice Hall

4. Sensation & Perception
4/15/2017
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5. Sensation & Perception
4/15/2017
Perceptual Set
What you see in the centre figures depends on the order in which you look at the figures:
If you scan from the left, see an old woman
If you scan from the right, see a woman’s figure
Figure 3.28 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall

6. Sensation & Perception
4/15/2017
Schemas
Through experience we form concepts, or schemas, that organize and interpret unfamiliar information.
Especially strong are out schemas for faces.
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7. Sensation & Perception
4/15/2017
Mona Lisa
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8. Sensation & Perception
4/15/2017
Form Perception
Gestalt principles describe the brain’s organization of sensory building blocks into meaningful units and patterns.
They generated laws of perceptual organization such as:
Figure and Ground
Laws of Grouping
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9. Sensation & Perception
4/15/2017
Figure and Ground
Organization of the visual field into objects (figures) that stand out from their surroundings (ground).
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10. Sensation & Perception
4/15/2017
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11. Gestalt Laws of Grouping
Sensation & Perception
4/15/2017
Gestalt Laws of Grouping
Proximity: Objects that are near each other will be perceived as belonging to a common set.
Seeing 3 pair of lines in A.
Similarity: Objects that are similar will be perceived as belonging to the same group.
Seeing columns of orange and red dots in B.
Figure 3.23 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall

12. Gestalt Laws of Grouping
Sensation & Perception
4/15/2017
Gestalt Laws of Grouping
Continuity: Tendency to perceive stimuli in a unified form.
Seeing lines that connect 1 to 2 and 3 to 4 in C, rather than four separate lines.
©1999 Prentice Hall

13. Gestalt Laws of Grouping
Sensation & Perception
4/15/2017
Gestalt Laws of Grouping
Closure: Grouping disconnected pieces into a meaningful whole.
Seeing a horse in D and “triangle.”
Connectedness: The tendency to perceive objects as belonging together when they are positioned together or are moving together.
©1999 Prentice Hall

14. Sensation & Perception
4/15/2017
Form Grouping
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15. Sensation & Perception
4/15/2017
Impossible Doghouse
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16. Sensation & Perception
4/15/2017
Depth Perception
Seeing objects in three dimensions enables us to determine distance.
Visual Cliff experiments
Gibson and Walker
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17. Sensation & Perception
4/15/2017
Visual Cliff
A laboratory device for testing depth perception in infants and young animals.
It suggests that the ability to perceive depth is at least partially innate.
©1999 Prentice Hall

18. Sensation & Perception
4/15/2017
Binocular Cues
Visual cues to depth or distance that require the use of both eyes.
Retinal Disparity: The slight difference in lateral separation between two objects as seen by the left eye and the right eye.
Convergence: Turning inward of the eyes, which occurs when they focus on a nearby object.
The more the inward strain the closer the object.
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19. Sensation & Perception
4/15/2017
Monocular Cues
Relative Size: The one that casts the smaller retinal shadow is further away.
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20. Sensation & Perception
4/15/2017
Monocular Clues
Interposition: if one object partially blocks another we perceive it as closer.
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21. Sensation & Perception
4/15/2017
Interposition
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22. Sensation & Perception
4/15/2017
Monocular Clues
Relative Clarity: We perceive hazy objects as farther away than sharp focused ones.
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23. Sensation & Perception
4/15/2017
Monocular Clues
Texture Gradient: A gradual change from a coarse, distinct texture to a fine, indistinct texture signals increasing distance.
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24. Sensation & Perception
4/15/2017
Monocular Clues
Relative Height: We perceive objects higher in our field of vision as further away.
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25. Sensation & Perception
4/15/2017
Monocular Clues
Relative Motion: As we move, objects that are actually stable appear to move.
The nearer the object the faster it seems to move.
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26. Sensation & Perception
4/15/2017
Monocular Clues
Linear Perspective: Parallel lines appear to converge with distance.
©1999 Prentice Hall

27. Sensation & Perception
4/15/2017
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28. Sensation & Perception
4/15/2017
Monocular Clues
Light and Shadow: Nearby objects reflect more light into our eyes than more distant objects. Given two identical objects, the dimmer one appears to be farther away.
©1999 Prentice Hall

29. Sensation & Perception
4/15/2017
In or Out?
©1999 Prentice Hall

30. Sensation & Perception
4/15/2017
Distance Cues
The moon just above the horizon
typically appears to be unusually
large because we perceive it as
unusually far away from ourselves.
This is a result of distance cues,
which make the horizon moon
seem farther away. The horizon
moon appears to shrink in size if it
is viewed through a narrow tube
that eliminates the perception of
distance cues. This illustrates the
importance of context effects.
©1999 Prentice Hall

31. Sensation & Perception
4/15/2017
Motion Perception
Phi Phenomenon: When two adjacent, stationary lights blink on and off in quick succession, we perceive a single light moving back and forth between them.
An illusion of movement
©1999 Prentice Hall

32. Sensation & Perception
4/15/2017
Motion Perception
Objects traveling towards us grow in size and those moving away shrink in size.
The same is true when the observer moves to or from an object.
©1999 Prentice Hall

33. Sensation & Perception
4/15/2017
Perceptual Constancy
Perceptual constancy enables us to perceive an object as unchanging even though the stimuli we receive from it change.
Thus, we can identify things regardless of the angle, distance, and illumination by which we view them.
Constant in terms of color, size and shape
©1999 Prentice Hall

34. Sensation & Perception
4/15/2017
Shape Constancy
Even though these images cast shadows of different shapes, we still see the quarter as round
Figure 3.25 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall

35. Sensation & Perception
4/15/2017
Size Constancy
We perceive objects as having a constant size, even while our distance from them varies.
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36. Sensation & Perception
4/15/2017
Lightness Constancy
We perceive an object as having a constant lightness even while its illumination varies.
Perceived lightness depends on relative luminance.
The amount of light an object reflects relative to its surrounding.
©1999 Prentice Hall

37. Sensation & Perception
4/15/2017
The Ames Room
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38. Sensation & Perception
4/15/2017
The Ames Room
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39. Sensation & Perception
4/15/2017
The Ames Room
A specially-built room that makes people seem to change size as they move around in it
The room is not a rectangle, as viewers assume it is
A single peephole prevents using binocular depth cues
Figure 3.24 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall

40. Sensation & Perception
4/15/2017
Visual Illusions
Illusions are valuable in understanding perception because they are systematic errors.
Illusions provide hints about perceptual strategies.
In the Muller-Lyer illusion (above) we tend to perceive the line on the right as slightly longer than the one on the left.
Figure 5.07 from
Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall

41. Sensation & Perception
4/15/2017
The Ponzo Illusion
Linear perspective provides context
Side lines seem to converge
Top line seems farther away
But the retinal images of the red lines are equal!
Figure 3.3Davis 2 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall

42. Sensation & Perception
4/15/2017
Fooling the Eye
The cats in (a) are the same size
The diagonal lines in (b) are parallel
You can create a “floating fingertip frankfurter” by holding hands as shown, 5-10” in front of face. Look beyond your fingers to experience the illusion.
©1999 Prentice Hall

43. Hearing:The Psychology of Sound
Sensation & Perception
4/15/2017
Hearing:The Psychology of Sound
Sound waves are really air molecules being pushed about.
Frequency: The length of the sound wave.
Pitch
Amplitude: The height of the sound wave.
Loudness
Timbre: Complexity of sound, mixtures of tones
Allows us to recognize a friends voice on the phone.
©1999 Prentice Hall