1. Sensation and Perception
Psychology Chapter 4 Section 1

2. Sensation and Perception
We experience the world through our senses
Most people know about the five senses. Can you name them?
Vision, hearing, smell, taste, and touch

3. How many senses do we have?
Depending on how you measure it, there could be 20 or so senses
Eyes: Rods: how much light there is
Eyes: Cones: colors– actually there are three, one for each primary color
Ears: there are two with the ears: hearing, balance
Skin: five skin senses: heat, cold, pain, itch, pressure
Nose: smell
Tongue: taste
But wait… there’s more…

4. More senses
Muscles/ joints: where our body parts are (thus we can walk without looking down, or touch our fingers with our eyes closed
Bladder: tells us when it’s time to urinate
Large intestine: tells us when we are full of food
We have hunger and thirst sensors
We have many other bodily sensations, like when we are about to sneeze or when your leg is tingly when it falls asleep
There’s another sense that tells us what position our body is in without us needing to look. (This sense helps a cat land on its feet.)
We even have a sense of time
So that’s more senses, and there’s still more

5. The number of senses could total up to a pretty good game of Bingo
(pain)

6. This chart organizes seven of the major senses

7. Truth or Fiction?
Discuss the six statements at the beginning of page 78.
Decide if each one is truth or fiction

8. Sensation and Perception
Read Page 77 about Marc
What was going on with Marc’s senses in the reading?
He tuned out background noise because he was so enamored with Linda’s voice. When Todd stepped on his toe, he was surprised and annoyed, and those intense feelings may have heightened his pain. Then, Linda’s concern seemed to soothe the pain.
Psychologists call these two different processes sensation (the feeling) and perception ( the interpretation of the feeling).

9. Sensation and Perception
Once we take in information through our senses, our brain then does something with that information and interprets it
The brain might decide whether or not the message is important enough to do something about it
What our brain decides depends on many factors: our mood, the circumstances, our cultural background, etc.

10. While sensations depend on physical ability to sense something, perception relies on the psychological ability to interpret that sensation

11. Sensation and Perception: The Basics
Sensation is the stimulation of sensory receptors and its transmission to the central nervous system
The stimulation of the senses is automatic– light, sound, and touch (or chemicals that stimulate smell or taste) are constantly stimulating the receptors

12. Sensation and Perception: The Basics
Perception is the psychological process through which we interpret sensory stimulation
Perception reflects learning, expectations, and attitudes, as our brain interprets stimuli

13. Sensation and Perception
Because of our perception skills and experience, we know that the people in the foreground of this picture are NOT that much bigger than the people in the background, despite the sensation produced by the stimulus
Sensation and Perception

14. A Good Test Question
Partner up and have the older partner explain the difference between sensation and perception, while the younger one listens.
Then have the younger partner explain as the older one listens.
I will then choose some random people to explain the difference to the class.

15. Sensation and Perception: The Basics
Sensation and perception are affected by several concepts. Three of these are:
Absolute Threshold
Difference Threshold
Signal Detection Theory

16. Absolute Threshold
Absolute threshold is the very lowest level where we can sense something
Typical Thresholds:
Vision: A candle flame from about 30 miles away on a dark night
Hearing: Ticking of a watch from 20 feet away
Smell: One drop of perfume diffused in a small house
Taste: One teaspoon of sugar dissolved in two gallons of water
Touch: A fly’s wing falling on a cheek from 0.4 inches away

18. Psychologists often define the absolute threshold as the lowest intensity that a person can detect 50 percent of the time. Anything less than that is subliminal

19. Difference Threshold
Difference threshold is our ability to detect differences between stimuli
Can you tell the difference between all these colors?

20. Signal Detection Theory
We focus on whatever we consider important
If our best friend were playing piano, we might hear it more than if it were somebody we didn’t know
If our nose is stuffy, we don’t taste things as well
If there’s noise in the room, we don’t hear as well
Signal Detection Theory takes all these outside influences into account when describing how much we sense a stimulus

21. Sensory Adaptation
Sensory Adaptation is the process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli
If you are in a dark room, your eyes adapt to the amount of light available and pretty soon you can see better
If you are on a long car ride, you start to tune out the humming motor after a while
If you jump into a pool of hot or cold water, after a while you adapt to it

22. Sensory Adaptation is sometimes confused with Habituation

23. Sensory Adaptation Experiment
Stare at his nose for 30 seconds and then look at the white space

24. Assessment
Complete Questions 1-3 on page 80