1. Sensation and Perception Activities and Demonstrations
What's New in Sensation and Perception?
Cathy A. Grover
Emporia State University
November 6, 2006

2. Activities & Demos JND & Weber’s Law Top Down Processing
Pulfrich Pendulum
Visual adaptation
Camouflage & Movement
Opponent Process Theory of Color Vision
Audition – Mosquito Tone
Tactile Recognition
Gustation – Influence of Vision on Taste
Olfaction – Odor Recognition

3. Psychophysical Measures
Difference Threshold or JND Activity
Materials
2 boxes of wooden matches or small paper clips for each pair
Put a large X on half of the boxes (both sides)
Instructions
Assign students in pairs of 2 (Perceiver & Experimenter)
Perceiver - close your eyes (use blindfolds if you can) & hold out your hands
Experimenter
Start off with 10 in standard box X & 11 in the unmarked comparison box
Place one box in each hand
Have the perceiver “Compare the weights of the two boxes with your eyes closed and try to decide which box is heavier”
If the perceiver can not identify the heavier box 3 out of 3 trials add one match to the comparison box
When the perceiver can identify the heaviest box 3 out of 3 times you have reached the perceiver’s difference threshold - write this # down
Begin over but this time with 30 in standard box X and 31 in the comparison box – write down the new difference threshold
Discussion
The Difference Threshold  as the weight of the standard gets larger
Demonstrating that there is not a 1:1 relationship between the physical stimulus and the psychological experience (Hence Fechner’s development of Weber’s Law DT/S = K)

4. Top-Down Processing & Perceptual Set
Information that a person brings to the situation influences both perception and recognition
Perceptual set
The context sets you up to perceive items relevant to the context

5. the context helps us to perceive the stimulus in the simplest manner

6. Again the context helps us to perceive the stimulus in the simplest manner

7. Notice that you can only perceive the center stimulus one way at any given moment

8. Perceptual Set
The context sets you up to perceive items relevant to he context

9. The Forest Has Eyes by Bev Doolittle (1985)

11. Right half of the class close your eyes
Costume Ball

12. Left half close your eyes
Trained Seal Act

13. As quickly as you possibly can say out loud what you see

14. Half the class close your eyes

15. Now the other half close your eyes

16. As quickly as you possibly can say out loud what you see

17. What you think you see is not always what you see
Materials
One dark lens for each student
One object on a long string
Instructions
Tie the string a from the ceiling a couple of feet in front of a white wall
Have students stand directly in front of the string at the back of the room and hold dark lens up to just the left eye wait about one minute for that eye to dark adapt
Swing stand just a bit to the side of the string and swing it back and forth
They should see the object hanging from the end swinging in a circle or oval and passing through you
After they have let their left eye light adapt again, repeat for the right eye
Discussion
Pulfrich Pendulum
Rods & Cones processing at different speeds demo
Show the following slide and explain that rods transduce information slightly slower than the cones. The visual cortex takes the two disparate pieces of information and translates it in to 3-d

19. Visual Adaptation Materials Instructions Discussion
Finger & eye (careful not to poke)
Instructions
Stare at a stationary object
Close one eye
Gentle push in on the outside corner of the open eye
Wait until you experience your visual filed go black
Discussion
You prevented your eye muscles from making tiny random movements
Adaptation
When we view a stimulus briefly the neurons responding to that stimulus fire action potentials. If we keep viewing that stimulus the neurons firing rate decreases and even stops
Adaptation occurs for all sensory systems
Smell - perfume or cologne in the morning
Taste - cooking and add spice
Hearing - volume of radio when you turn the car on in the morning
Touch - sitting down in classroom chair

20. Camouflage and Movement
Materials
Transparency
Over head projector
Instructions
Ask students what they see
Then move the top transparency
Now what do they see
Discussion
Camouflage
Very important for the prey
Perception of movement
Very important for the predator
Many Kansas students may have experineced this driving by a filed with corn stubble and birds flying in and landing
This activity also demonstrates the brief experience of “iconic memory”

21. Point-light Walkers Johnasson (1973)
Film a person standing in the dark with lights attached to them
When person is not moving the lights are meaningless
When the person walks the observer can identify it as a person
Observers accurately judge gender & emotion when lights are located on faces
Observers can accurately judge how far a person is trying to throw an object, as well as accurately judge the weight of a bowling ball
Observers are very accurate at detecting the type of species that is moving
Even good at this when there is visual noise (extra lights moving in other directions)
Infants & animals can do this too!

22. Color Perception Materials Instructions
Next slide
Instructions
Stare at the center of the flag (bottom right corner of yellow area) for one full minute
If you have to blink that is ok, but immediately focus on the same spot
When I say go move your focus to the black dot on the bottom of the slide
Discussion for Color Afterimage
Two theories of color vision
Trichromatic theory cones for red green blue
Opponent Process Theory
Only one ganglion cell of a pair of ganglion cells can fire at a time after fire for a long time and then stop firing the other ganglion cell fires rapidly to make up for having been turned off
Red-green, blue-yellow, black-white

24. Audition Presbycusis & the mosquito ring tone
Put your senses to the test
Just go to my useful links

25. Tactile Object Recognition
Materials
5-10 everyday items that fit in the palm of your hand and are familiar to students
e.g., plastic ring from milk jug, crumpled up piece of paper, binder clip
1 Scarf or blindfold
Instructions to class
Ask for a volunteer to come in front of the class
Have them sit in a tall chair and put the blindfold on
Ask them to hold their dominant hand out in front of them palm up
If setting at a desk have them lie their hand on the table palm up
Tell them that you are going to place an object in their hand, and without moving their hand in anyway they are to name the object
Won’t be able to identify the object
Next tell them they can move their hand anyway needed in order to recognize the object tactilely name the object
Discussion
We must be actively involved in order for a conscious sensory experience to occur
When not using our visual system, the somatosenses work with motor system to provide information about objects that come in contact with our skin
Recognition
Our ability to identify the stimulus as being in a category that has meaning
Explain the tactile information is sent to the somatosensory cortex and then to the verbal areas of the brain (mostly left temporal lobe) and association cortex where object names are stored in long-term memory
Using one item that they are not familiar with will demonstrate how experience is important for naming the object because even though a person can describe an object based on tactile sensory information, if they have no experience with it they can not recognize or name the item

26. Gustation Materials Instructions Discussion
Mashed potatoes (can use scramble eggs, vanilla pudding)
Food coloring
Instructions
Prior to activity
Color half of the mashed potatoes with all food colors
Blindfold student
Put 2 plates of mashed potatoes in front of them and have them taste both
Ask them “Which tastes better”
Then take blindfold off and ask which they would prefer to eat
Discussion
Perception of flavor is strongly influenced by what the food looks like. What looks appealing and tastes good depends on what you have learned

27. Olfactory Recognition Better than Recall
Materials
Flavor extracts for baking isle of grocery store
Cotton balls
Small containers like those that hold film
Instructions
Prior to the activity
Number the containers
Put one drop of extract on a cotton ball and place in container, recording which flavor is place in each container by # as you go
Place the container at various stations around the room
Have students go to each station and write down the # and the odor
Discussion
Our ability to name odors is poor, gets easier with practice
Also better when you are told what they are on first presentation and then again if fail to identify
Trouble is with our ability to retrieve the name from memory, not a deficiency with our olfactory system
We are sensitive to very small differences in odor intensity
Dogs ,000 times more sensitive to odors

28. Almond
Rum
Grape
Butterscotch
Banana
Mint
Water
Coconut
Raspberry
Watermelon
Cherry
Pina colada
Orange
Anise
Cinnamon
Wintergreen

29. Grape
Raspberry
Coconut
Cherry
Rum
Watermelon
Wintergreen
Butterscotch
Pina colada
Anise
Cinnamon
Water
Orange
Mint
Banana
Almond