Students observe and test their reflexes, including the (involuntary) pupillary response and (voluntary) reaction times using their dominant and non-dominant hands, as a way to further explore how reflexes occur in humans. They gain insights into how our bodies react to stimuli, and how some reactions and body movements are controlled automatically, without conscious thought. Using information from the associated lesson about how robots react to situations, including the stimulus-to-response framework, students see how engineers use human reflexes as examples for controls for robots.
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- Common Core State Standards for Mathematics: Math
- 5. Summarize numerical data sets in relation to their context, such as by:<ol type="a"> <li>Reporting the number of observations.</li> <li>Describing the nature of the attribute under investigation, including how it was measured and its units of measurement.</li> <li>Giving quantitative measures of center (median and/or mean) and variability (interquartile range and/or mean absolute deviation), as well as describing any overall pattern and any striking deviations from the overall pattern with reference to the context in which the data were gathered.</li> <li>Relating the choice of measures of center and variability to the shape of the data distribution and the context in which the data were gathered.</li></ol> (Grade 6)  ...show
- International Technology and Engineering Educators Association: Technology
- F. Knowledge gained from other fields of study has a direct effect on the development of technological products and systems. (Grades 6 - 8)  ...show
- Missouri: Science
- a. Describe how new technologies have helped scientists make better observations and measurements for investigations (e.g., telescopes, electronic balances, electronic microscopes, x-ray technology, computers, ultrasounds, computer probes such as thermometers) (Grade 5)  ...show
- f. Identify receivers of visible light energy (e.g., eye, photocell) (Grade 6)  ...show
- a. Make qualitative observations using the five senses (Grades 6 - 8)  ...show
- Next Generation Science Standards: Science
- Gather and synthesize information that sensory receptors respond to stimuli by sending messages to the brain for immediate behavior or storage as memories. (Grades 6 - 8)  ...show
- List typical human reaction times.
- Explain how the "stimulus-sensor-coordinator-effector-response" loop works in humans and in robots.
- meter-length ruler, wooden or plastic
- pencil, one per student
- Response & Reaction Worksheet, one per student
- computer and projector to show the Response & Reaction Presentation to the class
|reflex:||An involuntary and nearly instantaneous body movement in response to a stimulus, largely for self-defense and self-preservation.|
|response time:||The sum of reaction time and movement time.|
Before the Activity
- Gather materials and make copies of the worksheets.
- Be ready to show the class the Response & Reaction Presentation PowerPoint file.
With the Students
- Divide the class into groups of two students each. Hand out the worksheets.
- Allow 10 minutes for student pairs to conduct exercise 1, observing their pupillary light reflex responses (slide 2). Instructions (also on the slide and worksheet):
- Perform this exercise with a partner.
- Dim the room lights. After a few minutes, look at the eyes of your partner and note the pupil sizes (the black center spots in the middle of the eyes).
- Turn on the room lights. Check the pupil sizes again. The pupils should now be smaller.
- This is the pupillary light reflex response. This reflex "automatically" keeps out excessive light that may damage the eyes, and thus protects your eyes for you!
- Allow 25 minutes for student pairs to conduct exercise 2, testing reaction times (slides 2-6). Explain the exercise and review the instructions so they are clear to students: In your groups, you will perform four variations of a reaction test. As you collect data, fill in the worksheet data table. Then switch roles and repeat the tests and data collection. As necessary, demonstrate for students the ruler drop-n-catch set-up. Then let the student pairs proceed to conduct their own tests and collect data. Instructions (also on the slides and worksheet):
- For Test A: Hold a meter-long ruler near the end with the highest number and let it hang down. Have your partner put his/her dominant hand at the bottom of the ruler, not touching it, and be ready to grab the ruler when it drops. Tell your partner that you will drop the ruler sometime in the next five seconds with no countdown warning and that s/he is to try to catch the ruler as fast as s/he can after you drop it. Be consistent in where hands are placed at the start of each trial. Record in the data table the point on the ruler (centimeters or inches) at which your partner catches it. Repeat this test with the same subject for a total of three times. Vary the time of dropping within the five-second "drop-zone" so the subject cannot guess when you will drop the ruler.
- For Test B: Conduct the same test with the addition of a countdown warning. Tell your partner that you will drop the ruler at the count of three and say: 1... 2... 3 and drop it when you say 3. Record in the data table the point on the ruler where the partner caught it for this trial. Repeat this test with a countdown with the same subject for a total of three times.
- For Test C: Conduct the test with no countdown warning and your partner's eyes closed. Tell your partner that you will drop the ruler any time within a five-second "drop-zone." Record the data.
- For Test D: Conduct the test with a countdown warning, eyes closed, with the subject using his/her non-dominant hand. Tell your partner that you will drop the ruler at the count of three and say: 1... 2... 3 and drop it when you say 3. Record the data.
- Have students share and discuss their exercise 2 findings as a class. Then either have students answer the six worksheet results and analysis questions (slide 7) in writing or lead a class discussion using the questions as prompts.
- Conclude by administering the three-question Post-Lesson Quiz (slide 8, and attachment to associated lesson). As a class, summarize and highlight the key concepts:
- A reflex is an involuntary and nearly instantaneous body movement in response to a stimulus that is largely done for self-defense and self-preservation purposes.
- Response time is the sum of reaction time and movement time.
- Human reflexes and robot actions can be described using the "stimulus-sensor-coordinator-effector-movement" framework, which is very useful to understand both human and engineering systems.
- For more advanced students, provide additional explanatory material as found at the websites listed in the References section.
Dowshen, Steven. What Are Reflexes? Last updated September 2010. Kids Health from Nemours. Accessed April 16, 2013. http://kidshealth.org/kid/talk/qa/reflexes.html
List of reflexes (alphabetical). Last updated November 3, 2012. In Wikipedia, The Free Encyclopedia. Accessed April 16, 2013. http://en.wikipedia.org/w/index.php?title=List_of_reflexes_(alphabetical)&oldid=521175984
Mental chronometry. Last updated March 2, 2013. In Wikipedia, The Free Encyclopedia. Accessed April 16, 2013. http://en.wikipedia.org/w/index.php?title=Mental_chronometry&oldid=541675578
Your Sense of Touch. The Senses, Oracle ThinkQuest. Accessed April 16, 2013. http://library.thinkquest.org/3750/touch/touch.html
Marianne Catanho, Sachin Nair, Charlie Franklin, Satish Nair
© 2013 by Regents of the University of Colorado; original © 2012 Curators of the University of Missouri
GK-12 Program, Computational Neurobiology Center, College of Engineering, University of Missouri
Last modified: May 27, 2015