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Lani Chung

Mr. Nakamura

Biology HL Period 3B

7 March 2013

Reaction Time Lab Analysis Questions

1. Specifically, which parts of the nervous system were used when the student responded to the

dropped meter stick in the tests for visual stimuli?

When the student saw the meter stick begin to drop, the photoreceptors of the retina are

stimulated and they send impulses to the bipolar neurons and the ganglion cells. The axons from

the ganglion cells travel to the visual area of the cerebral cortex of the brain. The brain must then

correct the position of the image so that it is right side up and not revered. It must also coordinate

the images coming from the left and right eye. When the student tried to grab the meter stick

after receiving the visual stimuli, the somatic nervous system (SNS) is responsible for receiving

the sensory information and controlling the movement of their arm. The SNS carries nerve

impulses from the brain to the muscle to be moved which allowed the student to react to the

visual stimuli.

2. If you continued to repeat the test for visual stimuli, do you think you would get faster? Why or

why not?

If you continued to repeat the test for visual stimuli, you would probably get faster because you

can speed up nerve conduction through practice. By repeating the same movements, you make

them almost automatic. Although the action of grabbing the meter stick before it falls is not a

classical reflex, with practice, your movements almost mimic a reflex. They become motor skills

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that have been etched into your nerves and brain which causes the motor pathways to be almost

reflexive.

3. What factors would ultimately limit your speed of response?

The main factor that would ultimately limit your speed of response is the time that it takes for the

image of the visual stimulus to reach your eyes, as well as the time that it would take for the

visual stimulus to be sent to your brain and processed. Another factor is the time that it takes for

the muscles to contract after neurological impulses are sent to them.

4. How does a reaction differ from a reflex?

Reactions are different from reflexes in that they are voluntary responses to a stimulus from the

environment. It can be trained to become faster through regular practice. A reflex is an

involuntary and nearly instantaneous movement in response to a stimulus that is usually done to

protect the body from harm. It is generally much faster than a reaction

5. Draw a simple reflex arc that would occur when a person steps on a nail. Label all of the

neurons involved.

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6. List at least one more factor that would affect your reaction time and describe how you would

test it.

Another factor that would affect reaction time is fatigue. This factor can be tested by having

subjects first run a distance of 400 meters. Then the subjects will attempt to grab the meter stick

before it falls to the ground with their eyes open and essentially follow the procedure for the

visual stimulus test. The tiredness that results from the physically exertive task of running will

help to test the effect of fatigue on the reaction time of an individual.