BSL PRO Lesson H16: Active Learning: Reflexes & Reaction Time

This lesson is based on a presentation developed by Dr. Jennifer Lundmark and Ms. Andrea Salmi for the HAPS Conference, Phoenix, Arizona, May 25-30, 2002.

This PRO Lesson describes basic reflex and reaction time (visual stimulus) exercises and details hardware and software setup of the BSL Lessons System to record reaction time to auditory stimulus. All data collection and analysis is done via the BIOPAC MP data acquisition unit and the Biopac Student Lab Lessons software.

Active Learning With Inquiry-based Labs

Active Learning Lessons convert traditional physiology laboratories into inquiry-based exercises. Students perform a lab exercise designed to encourage them to make observations and develop and test multiple hypotheses during a single lab period using the BIOPAC data acquisition system. These inquiry-based exercises are designed to give students experience with the scientific method, group discussion, design of simple experimental protocols, and the responsibility of making their own decisions.

This "Active Learning” lesson allows students to participant in, rather than merely receive, their own education. This lesson assumes students are familiar with the basic concepts of reflex and reaction (response) time outlined below, and provides only the basic setup and recording steps students need to create their own experiment. Students will design an experiment to determine factors that affect reaction time and indicate specifically where in the nervous system sequence a factor had its effect.

To learn more about the benefits of Inquiry-based, Active Learning Labs, read these results from an NSF-CCLI Grant-Supported Project on Inquiry-based labs using the Biopac Student Lab System.

Abstract Dr. Jennifer Lundmark <lundmark@csus.edu> & Ms. Andrea Salmi <salmia@crc.losrios.cc.ca.us>

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REFLEXES

Reflexes are rapid, predictable motor responses to stimuli. Reflexes occur over specific neural pathways called reflex arcs. In this exercise, you will test reflexes that are initiated by stretch receptors (muscle spindles) within muscles. Stretching the muscle spindles stimulates a sensory neuron that conducts an impulse to the spinal cord. In the spinal cord, the sensory neuron generally stimulates an interneuron (but directly stimulates motor neurons in the knee jerk reflex). The motor neurons conduct impulses to muscles and stimulate them to contract.

One way to stretch muscle spindles is to strike a tendon with a rubber mallet. You will test several different reflexes in this manner.

REACTION TIME

Reaction time is the amount of time it takes for an individual to react voluntarily to a sensory stimulus. In the first exercise, students will test their reaction time to a visual stimulus. In the second exercise, students will test their reaction time to an auditory stimulus.

Some years ago, a world-class runner was repeatedly accused by his competitors of “jumping the gun” in races. He could only respond to these accusations by saying that he felt he had done nothing wrong. When footage of his races was reviewed, it became clear that he was in fact leaving the starting blocks before his competitors. As the evidence against him mounted, he underwent physiological testing which measured how long it took him to respond to external events or stimuli. It was revealed that his responses were some five to ten percent faster than those of an average runner, and this slight advantage enabled him to react faster once he heard the starter’s pistol. —BIOPAC Systems, Inc.

Objectives

1. Measure reflex response of the femoral, medial popliteal, musculocutaneous, and radial nerves. 2. Measure reaction time to visual stimulus. 3. Observe the effects of learning and physiological processes on reaction times of auditory stimulus. 4. Compare reaction times with two presentation schedules: fixed intervals and pseudo-random intervals

of auditory stimulus. 5. Design an experiment to determine factors that affect reaction time and indicate specifically where in

the nervous system sequence a factor had its effect.

Equipment

• BIOPAC push-button hand switch (SS10L) • BIOPAC headphones (OUT1) • Reaction Time Ruler or equivalent measure (divided into milliseconds, from 50 milliseconds at the

thumb line, to 400 milliseconds at the release end—see conversion chart) • Rubber mallet (or similar) • Chair • Desk or table • Colored pencils (for Lab Report) • Computer running Windows XP or Mac OS X • BIOPAC MP35/MP30 Data Acquisition Unit • Biopac Student Lab Lessons Software (Lesson 11: Reaction Time)

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Setup Hardware

1. Plug the push-button hand switch (SS10L) into CH 1 on the front of the MP unit. 2. Plug the headphones (OUT1) into the "Analog Out" port on the back of the MP unit. 3. Turn the MP unit ON.

Software 1. Launch the BSL Lessons software on the host computer. 2. Optional: Print the H16 Lab Report (PDF file) to complete it as you work.

Reflex Exercises One way to stretch muscle spindles is to strike a tendon with a rubber mallet. You will test several different reflexes in this manner.

1. Knee Jerk - tests the femoral nerve • Have the Subject sit with his or her legs hanging freely over the edge of the chair. • Strike the patellar ligament and observe the resulting muscle contraction. • Report: Which muscles contract? What causes these muscles to contract? What action occurs

at the knee joint? 2. Ankle Jerk - tests the medial popliteal nerve

• Have the Subject stand on one leg alongside a chair, with the other leg bent at the knee and its shin resting on the seat of the chair. The foot should project over the edge of the chair.

• Strike the Achilles tendon at ankle level and observe the resulting muscle contraction. o Report: Which muscles contract? What causes these muscles to contract? What action

occurs at the ankle joint? 3. Biceps Brachii Jerk - tests the musculocutaneous nerve

• Have the Subject rest an arm on the desk. • Locate the tendon of the biceps brachii muscle in the antecubital (anterior elbow) region. • Gently press the biceps brachii tendon with the thumb and strike the thumbnail with the mallet.

o Note the twitch in the biceps brachii muscle. Usually the contraction is too weak to produce any significant arm movement.

o Report: If the biceps brachii did produce a strong contraction, what action would occur at the elbow joint?

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4. Triceps Brachii Jerk - tests the radial nerve • Have the Subject lay his or her chest on the lab desk so that the upper part of the arm is resting

on the desk and the forearm is hanging over the edge of the desk. • Strike the tendon of the triceps brachii on the posterior surface of the elbow.

o Report: What action occurs at the elbow?

Reaction time: Visual Stimulus Exercises

1. Each pair of students should obtain a reaction time ruler and assign one student to start as the Releaser, and the other student to start as the Subject. • Look at the ruler and note that it is divided into milliseconds, from 50 milliseconds at the thumb

line to 400 milliseconds at the release end. The lines that are not numbered represent 10 milliseconds.

2. Get in position. • The Subject should sit in a chair, while the Releaser should stand facing the Subject. • The Releaser should hold the ruler at the release end, and the Subject should position the thumb

and index finger of the dominant hand on either side of the thumb line, about one inch apart. That is, the thumb line mark on the ruler should be between the Subjects’ thumb and index finger.

3. The Subject should indicate when he or she is ready to start, and the Releaser should then let go of the ruler anytime within the next 10 seconds. • The Releaser should not look at the Subject, or give any indication when he or she is going to

release the ruler. 4. The Subject should try to catch the ruler between the thumb and index finder as soon as it begins to

fall. 5. Report: Practice 10 drops, and then record the next 10 measurements in the Lab Report.

• The number of milliseconds it takes for the Subject to catch the ruler is read from the values on the ruler; use the value under the center of the thumb.

• It may be necessary to estimate the number of milliseconds if the center of the thumb does not fall directly on a labeled interval.

• If you do not have a Reaction Time Ruler, use the following conversion:

Distance Reaction Time 2 in (~5 cm) 0.10 sec (100 ms) 4 in (~10 cm) 0.14 sec (140 ms) 6 in (~15 cm) 0.17 sec (170 ms) 8 in (~20 cm) 0.20 sec (200 ms) 10 in (~25.5 cm) 0.23 sec (230 ms) 12 in (~30.5 cm) 0.25 sec (250 ms) 17 in (~43 cm) 0.30 sec (300 ms) 24 in (~61 cm) 0.35 sec (350 ms) 31 in (~79 cm) 0.40 sec (400 ms) 39 in (~99 cm) 0.45 sec (450 ms) 48 in (~123 cm) 0.50 sec (500 ms) 69 in (~175 cm) 0.60 sec (600 ms)

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OR to be more precise, use the following formula:

where, t = time (in seconds); y = distance (in cm); g = 980 cm/sec2 (acceleration due to gravity). Note: To use inches in your distance measurement, use g = 385.8 in/sec2.

Reaction Time — Visual Stimulus Trial # Subject A (msec) Subject B (msec)

1 __________ __________ 2 __________ __________ 3 __________ __________ 4 __________ __________ 5 __________ __________ 6 __________ __________ 7 __________ __________ 8 __________ __________ 9 __________ __________

10 __________ __________ 6. Have the Subject and the Releaser change places and repeat steps 2-5 7. Report: Calculate the average reaction time (msec) for both Subjects.

Reaction Time: Auditory Stimulus Exercises

1. Open the Reaction Time lesson, L11-React-1.

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2. Have the Subject put on the headphones, hold the hand switch in his/her dominant hand, close his/her eyes and relax.

3. Click Calibrate and then click OK to start the 8 second calibration procedure. 4. The Subject should quickly and briefly press the button on the hand switch when he or she hears a

click.

• This will happen about 4 seconds into the recording. At the end of the 8 seconds, verify that a spike appears on the screen. If so, you are ready to record. Otherwise, redo the calibration procedure.

6. The Subject will now record four segments of data; the Subject should sit quietly with closed eyes during the four segments of data collection.

• The first two segments will present 10 clicks at pseudo-random intervals, varying from 1 to 10 seconds between clicks.

• The second two segments will present 10 clicks at fixed intervals, every 4 seconds. 7. When ready, click Record to start the first segment.

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8. The Subject should quickly and briefly press the button when he or she hears a click. • At the end of the 10 clicks, the recording will automatically stop.

8. Allow the Subject to relax for a moment, then click Resume and do the next set. 9. Continue until all four sets of data have been collected. 10. Click Done and choose “Analyze current data file” or "Save As" from the pop-up window.

• Note: Following the press of the Done button, the program automatically calculates all 10 reaction times and the average reaction times for each trial and places them in the Journal window on the bottom of the screen. Use this Journal information to fill in your Lab Report.

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Design an Experiment

Conform to the Scientific Method A. Identify a problem or objective. B. Form a hypothesis. C. Test the hypotheses by observation and experimentation. D. Interpret the data. E. Draw conclusions (design a new experiment if data do not

support the hypothesis) F. Report observations and conclusions.

1. Determine at least two factors that might affect the reaction time of your subject.

2. Develop two hypotheses and show them to your instructor before proceeding.

3. Using the Biopac Student Lab Lessons menu, start Lesson 11 again.

4. Collect your data.

5. Explain the results; that is, why did the tested factors affect the reaction time of your subject?

6. Indicate specifically where in the nervous system sequence your factor had its effect.

Analysis

The BSL software offers a wide array of measurement and analysis tools to provide precise analysis of reaction time. Some analysis options follow.

For detailed analysis and additional questions, print and complete the H16 Lab Report (PDF file).

1. Set up your display window for optimal viewing of the first marker and pulse of the first segment.

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2. Set up a measurement box for CH 1 = Delta T.

3. Select an area from the first marker to the leading edge of the first pulse and note the ΔT measurement. o The marker indicates the start of the stimulus click. o The leading edge of the pulse indicates when the button was first pressed. Leading edge is

defined as the point where the pulse first reaches its peak. o The threshold that the program uses to calculate reaction time is 1.5mV.

4. Look at the first reaction time result in the Journal and compare this to the ΔT measurement found above--they should be approximately the same.

5. Repeat the steps above on other pulses until you are convinced that the Journal readings are accurate. 6. Report: Print the Journal or transfer your data from the Journal to the Data Report. 7. Report: Record the average values for the four exercises below, and convert to milliseconds.

Reaction Time — Auditory Stimulus

Segment #: Presentation Subject A

seconds Subject A

msec Subject B seconds

Subject B msec

Segment 1: Pseudo-random

__________ __________ __________ __________

Segment 2: Pseudo-random

__________ __________ __________ __________

Segment 3: Fixed-interval __________ __________ __________ __________

Segment 4: Fixed-interval __________ __________ __________ __________

8. Report: Collect data from at least five other Subjects as needed to complete the Lab Report. Calculate the mean for each presentation to determine if reaction times vary as the Subjects progress through the series of stimulus events.

A. Group Summary Complete Table 11.3 with the mean for five Subjects and calculate the group mean.

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B. Variance and Standard Deviation Calculate the variance and standard deviation for five Subjects with data from Segment 2: Pseudo-random Trial 2 and from Segment 4: Fixed Interval Trial 2.

C. Questions

a. Did reaction times vary as the Subjects progressed through the series of stimulus events?

b. Describe the changes that occurred in the mean reaction time between the 1st and 10th stimuli presentation: For Segment 1: For Segment 2:

Which segment showed the greatest change in mean reaction time? Segment 1 Segment 2

c. Estimate the minimal reaction time when reaction time becomes constant: sec

d. What physiological processes occur between stimuli presentation and pressing the hand switch?

e. Which presentation schedule had a lower group mean? Pseudo-random Fixed-interval

f. Which of the presentation schedules seems to have less variation (lower variance and lower standard deviation)?

Pseudo-random Fixed-interval g. State a plausible relationship between the difficulty of a task and the reaction time statistics: mean,

variance, and standard deviation.

h. What differences would you predict in reaction times and learning between your right and left hands?

9. Save or Print the data file. 10. Exit the Biopac Student Lab program.

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Appendix Inquiry-based Labs / Active Learning

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