Perception and the Brain
Grade level(s):Middle School (6-8), High School (9-12), Grade 6, Grade 7, Grade 8, Grade 9, Grade 10
Topic:Human Perception, Brain function
What you perceive is a combination of what you physically sense and how your brain interprets it.
What you need:
optical illusion (either hand-out or computer with projection) (can use Optical Illusions Kit, K029 from SEP Resource Center)
human brain, trays to hold the brain, gloves (WS70, WS71, WS72, WS84, WS162, WS163, or WS164 from SEP Resource Center)
prism goggles (K113 or K131 from SEP Resource Center:)
poster board and post-it notes
The lessons starts individually for the optical illusion. Then to pairs for the prism goggles. Then, it goes to two groups for the brain. Then back to individuals for lesson wrapup.
50 min total
5 min - Optical illusion
10 min - Prism goggles
10 min - Discussion of perception
15 min - Brain
10 min - Wrapup
In this lesson, students are introduced to how the brain interprets and uses sensory information from the visual system to guide how the body moves and performs various tasks. This lesson makes use of a specialized set of goggles with prism lenses that shift what the wearer sees. Using these prism goggles, students will see first hand how the brain adapts over time to changes in what we perceive. The lesson also makes a connection to the brain and brain function by giving students a chance to see and touch a preserved brain specimen.
Students have had some practice making scientific observations and asking questions. In addition, it is helpful for students to have had practice collecting basic data such as tallying numbers, making a table, etc.
The students will be able to describe perception. The students will understand that perception is a combination of what is physically sensed and how the brain interprets that sensation.
The goggles used in this activity have a special ridged surface adhered to the lenses. The ridges on this surface are all oriented in the same way and act as prisms that cause the light that enters through them to refract at a specific angle. The result of this is that what you see through the goggles is side-shifted in a particular direction, either to the left or to the right, depending on the goggles. Initially, this is disorienting to the person wearing the goggles, causing the person to have difficulty making accurate motions during any target-oriented task, but over time, the person is eventually able to adjust to the shifts in vision and perform motions accurately through repetition of a given task.
The Prism Goggle experiement demonstrates these facts:
- the human brain uses sensory information to make our bodies move and perform skills
- if we alter the sensory information the brain receives, it can be tricked into sending incorrect movement commands to the body
- the brain learns and adapts to the sensory change until it figures out how to make the body move as planned to accomplish the desired task – this happens with repetitive training
- the new learning can be reversed by correcting the visual misinformation and re-practicing the skill
Prior to the beginning of the lesson, setup an LCD projector and computer to show the optical illusion or make printed copies of an optical illusion for each student as a beginning activity.
Lesson Implementation / Outline
Students get introduced to perception by having an optical illusion waiting at their desk or projected on the board. We used the first illusion at http://kids.niehs.nih.gov/illusion/illusions.htm and projected it on the board. This optical illusion is also shown below:
If your eyes follow the movement of the rotating pink dot,
the dots will remain only one color, pink.
However if you stare at the black " +" in the center, the moving dots turns to green.
Now, concentrate on the black " + " in the center of the picture.
After a short period, all the pink dots will slowly disappear, and you will only see only a single green dot rotating.
It's amazing how our brain works. There really is no green dot, and the pink ones don't really all disappear. This should be proof enough, we don't always see what we think we see.
Activity and image source: http://kids.niehs.nih.gov/illusion/illusions.htm
Prism goggle Activity:
- Provide a brief demonstration of how to perform the activity before the students are divided into groups. During the demonstration, it is good not to reveal what is going to happen. The directions for the activity are below:
- Students will work in pairs and each pair will receive one set of prism goggles.
- They are instructed to reach out and try to touch their partner's finger five times without goggles on.
- Students will then put on the goggles and try the same task another five times. (see note below about "cheating" with the goggles on)
- Students will then take off their prism goggles and try again. Then the partners switch and repeat.
- Have students perform the activity
- Take a class tally of the results by asking for a show of hands for how many people were able to get their partners finger 5 times? 4 times? etc. With the goggles on? After taking them off?
- Ask the class if they have any observations about the experiment. Possible guiding questions: What did it feel like to have the goggles on? Why do you think it made it hard to touch things? Was it still hard when you took the goggles off? Here you can reiterate/introduce the concept of plasticity - your brain is able to change and learn things. For example, it became easier and easier to touch the finger with the goggles on.
- It can be disorienting when first putting the prism goggles on. Students should be advised to not walk around with the prism goggles on. Or instructors should be on the look-out for students trying to walk around the classroom with prism goggles on.
- Students can "cheat" at the activity (adapting to the goggles faster) if they leave their "throwing" hand in front of their visual field. It's best to instruct the students to pull their hand all the way back (ie: behind their head) in between each time of touching the target finger of their partner.
- Some students find the prism goggles to be very silly looking on other students. This can lead to difficult classroom management. One strategy to deal with this is to have every student put the glasses on and give the class a brief amount of time (1-2 minutes) to laugh at each other. Then laughing has to stop in order to conduct the experiment.
Explanation of perception and plasticity:
- Provide a brief explanation of why they see optical illusions and the changes that occurred in the prism goggle activity: explain that what you physically sense is then interpreted by your brain. This is called perception. In the optical illusion, depending on where you focus your vision, your brain chooses to interpret different parts of what's actually there and sometimes can misinterpret what is actually there. With the prism goggle activity, the goggles actually change the way things look and so your brain receives faulty information. In both cases, we saw that your perception can be altered: either by the brain misinterpreting information (like the optical illusion) or by faulty information being given to the brain (like the prism goggles).
- In the prism goggle activity, we also saw that your brain is capable of adjusting your body motions to changes in the environment that are detected through sensory perception. This is because during any task that you perform, your brain is using your senses to provide constant feedback about what you are doing. This is very useful to us in learning new things and also being able to adjust to changes in our environment. This is called plasticity
- Ask the students if they can think of other areas in their lives where plasticity helps them? (Suggest answer of doing homework to learn material, practicing an instrument, doing drills in a sport, etc.)
- Divide the class in two large groups and bring out two halves of a human brain.
- Students are given a glove and are allowed to touch the brain, if they would like.
- Students are also able to talk and ask questions about the brain. Have students share their observations using guiding questions such as, what does it look like? feel like? How different/similar do you think it might be to other species' brains? What about to other organs?
We end the lesson with a brief reminder about what perception and plasticity are.
We then ask the students to write down on a post-it note something that they learned during the lesson and something that they still wanted to know about the brain and learning. We have them put the note up on a posterboard in the front of the class.
We end with an acknowledgement of what they say they have learned and an attempt to answer any questions they have put up or suggesting where they might find the answers to their questions.
Extensions and Reflections
A good extension of this lesson is talk more about brain function and how your brain makes new connections through neurons when you learn something new. One possible activity is to have students view neurons under a microscope and to show videos/images of neurons growing new axons over time.