1. Chapter 8: Sensation & Perception
Psychology
Mr. Schabo
Crestwood High School

2. Do-Now: (Discussion) If you had to sacrifice one of your five senses:
Sight
Hearing
Touch
Smell
Taste
Which one would it be? Why?

3. Sensation vs. Perception
What occurs when a stimulus (change in environment, to which an organism responds) activates a receptor
Perception:
The organization of sensory information into meaningful experiences

4. Ambiguous Figure
Colored surface can be either the outside front surface or the inside back surface of the cube
Cannot simultaneously be both
Brain can interpret the ambiguous cues two different ways

5. The Riddle of Separate Sensations
Sense receptors
Specialized cells that convert physical energy in the environment or the body to electrical energy that can be transmitted as nerve impulses to the brain.

6. Sensation & Perception Processes

7. Doctrine of Specific Nerve Energies
Different sensory modalities exist because signals received by the sense organs stimulate different nerve pathways leading to different areas of the brain.
Synthesia
A condition in which stimulation of one sense also evokes another.

8. “Fraser’s Spiral”

9. Why does this image appear to be a spiral?
“Fraser’s Spiral”
Why does this image appear to be a spiral?

10. “Fraser’s Spiral” In viewing “Fraser’s Spiral:”
What are we sensing?
What are we perceiving?
How do we use sensation and perception together to understand our world?

11. Measuring Senses Absolute threshold Difference threshold
Signal-detection theory

12. Absolute Threshold
The smallest quantity of physical energy that can be reliably detected by an observer.

13. Absolute Sensory Thresholds
Vision:
A single candle flame from 30 miles on a dark, clear night
Hearing:
The tick of a watch from 20 feet in total quiet
Smell:
1 drop of perfume in a 6-room apartment
Touch:
The wing of a bee on your cheek, dropped from 1 cm
Taste:
1 tsp. Sugar in 2 gal. water

14. Difference Threshold
The smallest difference in stimulation that can be reliably detected by an observer when two stimuli are compared;
Also called Just Noticeable Difference (JND).

15. Spot the differences…How many can you find?

16. Difference Threshold

17. Sensory Adaptation Sensory Adaptation:
Senses tuned to change; adaptable
Responsive to increases and decreases of stimuli
E.g.:
Eyes adjust to darkness in a movie theatre
Skin adapts to coldness of ocean water

18. What would happen if we did not have “sensory adaptation?”
Can you think of other examples of how our senses adapt to changes in external stimuli?
What would happen if we did not have “sensory adaptation?”

19. Without Sensory Adaptation..
Without sensory adaptation, the human body would be overloaded with stimuli.
For example, right now we would be feeling the constant pressure of the clothing we are wearing, the chairs on which we are seated, etc.

20. “The Disappearing Circle”

21. “The Disappearing Circle”
When focusing on the black dot, why does the outer grey circle appear to fade away?

22. Signal-Detection Theory
Signal Detection Theory describes the relations between motivation, sensitivity, and decision making in detecting the presence or absence of a stimulus.
With everything going on around us, how and why so we choose to focus on the things we do?

23. “The Stroop Effect” (Part A.)

24. “The Stroop Effect” (Part B.)

25. “The Stroop Effect” (Part C.)

26. “The Stroop Effect”
Why is it more difficult to name the colors in “Part C.?”
The “Stroop Effect” illustrates how difficult it is to ignore some kinds of stimuli
You were receiving two stimuli – the color and the word – which compete and slow you down when you try to name the color

27. Review What is the difference between sensation and perception?
What is sensory adaptation? Why do humans adapt to stimuli?