1. Copyright © Allyn and Bacon 2006

2. Copyright © Allyn and Bacon 2006

3. Sensation and Perception
Chapter 4
Sensation and Perception
Copyright © Allyn and Bacon 2007

4. Copyright © Allyn and Bacon 2006

5. Copyright © Allyn and Bacon 2006
Sensation
An early stage of perception in which neurons in a receptor create an internal pattern of nerve impulses that represent the conditions that stimulated it – either inside or outside the body
Or simply…
The physical experiences of stimuli
Copyright © Allyn and Bacon 2006

6. The Basics
We do not actually experience the world directly, but instead we experience it through a series of “filters” we call senses.
The study of these sense and their effect on our behavior is called sensory psychology.

7. Perception The interpretation of our sensations Or simply…
A process that makes sensory patterns meaningful and more elaborate
Or simply…
The interpretation of our sensations
Perception draws heavily on memory, motivation, emotion, and other psychological processes to give them meaning.

8. How Does Stimulation Become Sensation?
The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural impulses
The human mind lacks direct access to the outside world.
All external events are filtered through the sense organs and then combined with the individual’s unique mix of memories, emotions, motives, and expectations.

9. Stimulation  Transduction  Sensation  Perception
All the senses….
1. Transduce stimulus energy into neural impulses
2. Are more sensitive to change that constant stimulus
3. Provide us information about the world
Stimulation  Transduction 
Sensation  Perception

11. Copyright © Allyn and Bacon 2006
Transduction
The process that converts physical energy, (such as light or sound waves,) into neural messages…the only language the brain understands
Receptors
Specialized neurons that are activated by stimulation and transduce (convert) it into a nerve impulse
Copyright © Allyn and Bacon 2006

12. Bottom-Up and Top-Down Processing
Bottom-Up Processing Analysis that stress features of the stimulus, rather than internal concepts
Example: Noticing a flower in a field
If your attention is drawn to a flower in a field, it may be simply that the flower is more visually outstanding than the surrounding field….you didn’t have to think about it

13. Bottom-Up Processing
In bottom-up processing, the resulting percept is determined by stimulus features.
Color, size, shape…

14. Bottom-Up and Top-Down Processing
--Expectations Memories Knowledge Cultural background and other cognitive factors
….influence perception

15. Top-down does not emphasize stimulus features
T0p-Down Processing
Top-down processing is also known as conceptually driven processing.
Top-down does not emphasize stimulus features

16. Even though the second letter in each word is ambiguous, top down processing allows for easy disambiguation based on the context.

17. Top-Down Processing
Your dog has been lost for three days, and you cannot stop thinking about him.
When you hear a dog bark, you assume that it is your dog.

22. Figure 6. 1 What’s going on here
Figure 6.1 What’s going on here? Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers

25. Bottom-Up and Top-Down Processing
--Expectations Memories Knowledge Cultural background and other cognitive factors
….influence perception

27. Bottom-Up and Top-Down Processing
--Expectations Memories Knowledge Cultural background and other cognitive factors
….influence perception

35. Why Have Attention? Limited resources Attention: Too much information
selects important/relevant information

36. Types of Blindness
Inattentional Blindness: Failing to see visible objects when our attention is directed elsewhere.
Change Blindness: Failing to notice change in the environment around us.

37. Cocktail Party Effect
Phenomenon of being able to focus one's auditory attention on a particular stimulus while filtering out a range of other stimuli
a partygoer can focus on a single conversation in a noisy room.
Allows most people to "tune into" a single voice and "tune out" all others.
also describes why one may immediately detect words of importance originating from unattended stimuli
for instance hearing one's name in another conversation