Perception Chapter 5

1. Perception Chapter 5

2. What is Perception? • Organization of information to make it useful

3. Psychophysical Approach • Psychophysics – behavioral aspects of a response to stimuli • Difference threshold – degree of change in a stimulus necessary for a person to detect the difference

4. Psychophysical Approach • Signal-detection theory - sensitivity to stimuli • Physical condition • Motivation • Mood • Attitude

5. Perceptual Constancies • Our brain becomes a storehouse of knowledge about details • Size, shape and color • Memories play a role in interpreting new stimuli

6. Four Constancies • 1. Size • 2. Shape • 3. Brightness • 4. Color

7. Perceptual Organization • Constructionist View • The brain constructs a perception out of many individual sensations

8. Gestalt Psychologists • Max Wertheimer • Whole is more important than the sum of the parts • Each part affects every other

9. Gestalt Laws of Perception • 1. Law of Proximity – tendency to group things together that are close to one another

10. Gestalt Laws of Perception • 2. Law of Similarity – group things together that have some visual element in common, such as size, shape, or color.

11. Gestalt Laws of Perception • 3. Law of Continuation – tendency to see interrupted lines as continuous lines

12. Gestalt Laws of Perception • 4. Law of Closure – Tendency to fill in missing details to complete a figure

13. Figure and Ground • 3 Principles • 1. The figure is more “thinglike” and more memorable than the ground • 2. The figure is seen as being in front of the ground • 3. The ground is seen as unformed material and seems to extend behind the figure

14. Bodily Depth Cues • Monocular cues – one eye • Binocular cues – two eyes • 1. Accommodation – change in the shape of the lens that varies with distance (1 eye) • 2. Convergence – the way the eyes rotate inward and outward with changes in distance (2 eyes) • 3. Binocular disparity – difference between the images provided by each eye

15. Pictorial Depth Cues • Monocular cues • Give a two-dimensional painting, photograph, or movie the illusion of depth where none exists.

16. Pictorial Depth Cues • 1. Linear perspective – parallel lines appear to converge as they move away from you • 2. Relative size – objects that are known to be the same size will convey depth if one is smaller than the other • 3. Relative height – objects that are higher in a scene are usually perceived as being more distant

17. Pictorial Depth Cues • 4. Overlap – a sensation of depth is created when one object partially blocks another • 5. Texture – changes in texture can convey depth • 6. Atmospheric (aerial)- distant objects tend to look less sharp than close objects • 7. Relative motion – objects that are close to the car seem to be moving by quickly, while objects in the distance appear to move slowly

18. Perception of Motion • Different kinds of movement: • A figure moving against a stationary background • Objects at rest against a moving background • Objects moving at different speeds in relation to each other • Observer’s own movements in relation to his/her surroundings • Induced movement • perception of movement of an object that is not moving

19. Illusions • Muller-Lyer Illusion • Which line appears longer?

20. Illusions • Ponzo Railroad Track Illusion • Which of the two horizontal lines on the track appear longer?

21. Illusions • The Necker Cube • The cubes seem to shift and another side seems closer to you. • Then it shifts back again

22. Illusions • The Boring Figure • Designed by E.G. Boring • Ambiguous figure • Young girl/old woman

23. Illusions • The Ames Room • Albert Ames • Appears to be a normal room • Actually shaped so the left corner is almost twice as far from the viewer as the right corner • The viewer perceives the nearer person as being much larger than the other, although both are exactly the same height

24. Illusions What do you see?

25. Illusions