1. Sensation & Perception

2. Sensation and Perception
The process through which the senses pick up visual, auditory, and other sensory stimuli and transmit them to the brain; sensory information that has registered in the brain but has not been interpreted
Perception
The process by which sensory information is actively organized and interpreted by the brain 2 2

3. Perception Gestalt principles of perceptual organization Figure-ground
Organization depends on what we see as figure (object) and what we perceive a ground (context).
Similarity
Objects that have similar characteristics are perceived as unit.
Proximity
Objects close together in space or time perceived as belonging together.
Continuity
We tend to perceive figures or objects as belonging together if they appear to form a continuous pattern.
Closure
We perceive figures with gaps in them to be complete. 2 2

4. Perception
You can see a white vase as figure against a black background, or two black faces in profile on a white background 2 2

5. Perception 2 2

6. Perception Perceptual constancy
The tendency to perceive objects as maintaining stable properties (e.g., size, shape, brightness, and color) despite differences in distance, viewing angle, and lighting
Size constancy
Perceiving objects as being about the same size when they move farther away
Shape constancy
Perceiving objects as having a stable or unchanging shape regardless of changes in the retinal image resulting from differences in viewing angle 2 2

7. Perception 2 2

8. Perception Monocular depth cues
Depth cues that can be perceived by only one eye
Types of cues
Interposition
When one object partly blocks your view of another, you perceive the partially blocked object as farther away
Linear perspective
Parallel lines that are known to be the same distance apart appear to grow closer together, or converge, as they recede into the distance 2 2

9. Perception Monocular depth cues Types of cues Relative size
Larger objects are perceived as being closer to the viewer, and smaller objects as being farther away
Texture gradient
Near objects appear to have sharply defined textures, while similar objects appear progressively smoother and fuzzier as they recede into the distance
Atmospheric perspective
Objects in the distance have a bluish tint and appear more blurred than objects close at hand 2 2

10. Perception Monocular depth cues Types of cues Motion parallax
When you ride in a moving vehicle and look out the side window, the objects you see outside appear to be moving in the opposite direction
Objects seem to be moving at different speeds – those closest to you appear to be moving faster than those in the distance
Objects very far away, such as the moon and the sun, appear to move in the same direction as the viewer 2 2

11. Perception James Gibson
Pointed out that our perceptions of motion appear to be based on fundamental, but frequently changing, assumptions about stability
Our brains search for some stimulus in the environment to serve as the assumed reference point for stability
When you’re driving a car, you sense the car to be in motion relative to the outside environment 2 2

12. Perception Depth perception Binocular depth cues
The ability to see in three dimensions and to estimate distance
Binocular depth cues
Depth cues that depend on two eyes working together
Convergence
Occurs when the eyes turn inward to focus on nearby objects – the closer the object, the greater the convergence
Binocular disparity (or retinal disparity)
Difference between the two retinal images formed by the eyes’ slightly different views of the objects focused on 2 2

13. Perception Ambiguous figures
Can be seen in different ways to make different images
Best known ambiguous figure is “Old Woman/Young Woman,” by E. G. Boring 2 2

14. Copyright © Allyn & Bacon 2005
What do you see?
Now what do you see?
Copyright © Allyn & Bacon 2005 2 2

15. Perception Impossible figures Do not seem unusual at first
Figures that cannot be built 2 2

16. Perception 2 2

17. Perception
Illusion
A false perception of actual stimuli involving a misperception of size, shape, or the relationship of one element to another 2 2

18. Perception Müller-Lyer Illusion
The two lines above are the same length, but the diagonals extending outward from both ends of the lower line make it look longer than the upper line 2 2

19. Influences on Perception
Bottom-up processing
Information processing in which individual components or bits of data are combined until a complete perception is formed
Top-down processing
Application of previous experience and conceptual knowledge to recognize the whole of a perception and thus easily identify the simpler elements of that whole 2 2

20. Influences on Perception2 2

21. Influences on Perception2 2

22. Influences on Perception
Perceptual set
An expectation of what will be perceived, which can affect what actually is perceived
David Rosenhan
David Rosenhan and some of his colleagues were admitted as patients to various mental hospitals with “diagnoses” of schizophrenia
Once inside, they acted normal but the staff members only saw what they expected to see and not what was actually occurring
The real patients were the first to realize that the psychologists were not really mentally ill 2 2

23. Influences on Perception
Inattentional blindness
The phenomenon in which we miss an object in our field of vision because we are attending to another 2 2

24. Influences on Perception
Simons and his colleagues
Showed participants a videotape of a basketball game in which one team is uniformed in white and the other in black
Instructed them to count how many times the ball was passed from one player to another either on the white or black team
About a third of participants typically fail to later recall the presence on the screen of even extremely incongruent stimuli (e.g., a man dressed in a gorilla costume) under such conditions 2 2

25. Influences on Perception
Social perception
Facial expressions, the visual cues for emotional perception, often take priority over the auditory cues associated with a person’s speech intonation and volume, as well as the actual words spoken 2 2