Caffeine and Reaction Time Essay
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Nov 19th, 2019

Caffeine and Reaction Time Essay

1) Identify the Problem or Question

How does the consumption of caffeine affect the reaction time of the nervous system?

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2) Introduction

Purpose of the experiment: To identify the whether or not caffeine increases or decreases the reaction time of the nervous system.

In our experiment, we have decided to use all the “cases” which will test how fast a signal from our brain will be sent to our muscles in order to click the mouse when we see an object or directions on the screen.

We know that the commonly used drug, caffeine, increases the heart rate, thus the increase in blood flow. The question in our experiment is, does the increase of blood flow, caused by caffeine, positively or negatively affects the reaction time that it takes to click the mouse the moment we see an approaching object.

Another underlying factor we can analyze in our experiment is gender and age. Since we are using test subjects whose ages and gender vary from 16 to 50 and from male to female, we can roughly conclude whether or not age and gender affect reaction time.

The reason we say roughly, is that the two factors, age and gender, are being “tested” in conjunction with the consumption of caffeine. We do not know if the consumption of caffeine and its effects vary for how old the person is and his or her gender.

3) Research and Current Ideas

In past experiments, people have concluded that there is an inconsistency in results depending on the amount of caffeine consumed. Apparently, a half-cup of coffee had faster reaction times than the reaction times that were drawn when the test subject drank a full cup of coffee. The person had concluded that too much caffeine could actually impair reaction time, but the right dosage could potentially increase reaction time.

4) Predict a solution to the problem or an answer to the question

Scientific Hypothesis: The consumption of 12oz of ground coffee will speed up our reaction time. Using past experiments conducted by other people, and the chemical compounds of caffeine and its affects on our body, we have drawn this hypothesis.

Dependent Variable: Reaction time

Independent Variable: Condition of the test subject (Caffeine)

The reaction time is the dependent variable, because the results depend on the condition of our subject. The condition of the test subject is the independent variable because we are changing the state of our test subject by increasing their caffeine levels.

5) Design the experiment to be used to test your hypothesis


* 4 tablespoons/24 of Maxwell house coffee blend
* Computer/Internet
* 4 test subject (2 16 year olds/ 2 middle aged adults, one of each gender) * Serendip software


1) Complete a control experiment by conducting the serendip experiment while you are in your natural state for each test subject. 2) The site for the serendip activity is: 3) Make sure that each “Case” is done 10 times to ensure accuracy. 4) Click “Results Summary” and record the information given. 5) Have each test subject consume 12 oz (2 tablespoons) of the Maxwell House Coffee blend. 6) Wait five minutes before the test subject goes through the serendip reaction time activity again. 7) Repeat steps 1-3 for each test subject, except after he or she has consumed the coffee and waiting for a duration of 5 minutes before completing the serendip activity. 8) Record the results in a data table.

6) Carry out the experiment

Test Type| Control Experiment| Experiment w/ Caffeine|
Act | 219 +- 15 milliseconds| 194+- 11 milliseconds|
Think, Act| 270 +- 32 milliseconds| 243 +- 28 milliseconds| Read, Think, Act| 394+- 74 milliseconds| 364 +- 68 milliseconds| Read, Think-Negate, Act| 383+- 102 milliseconds| 352 +- 64 milliseconds | Jazmine Ortiz, 16, Female

Jazmine Ortiz, 16, Female

Daniel Kim, 16, Male
Daniel Kim, 16, Male

Test Type| Control Experiment| Experiment w/ Caffeine|
Act | 210 +- 10 milliseconds| 191+- 8 milliseconds|
Think, Act| 267 +- 31 milliseconds| 236 +- 25 milliseconds| Read, Think, Act| 381+- 74 milliseconds| 344 +- 60 milliseconds| Read, Think-Negate, Act| 375+- 102 milliseconds| 342 +- 58 milliseconds | Test Type| Control Experiment| Experiment w/ Caffeine|

Act | 384 +- 72 milliseconds| 298+- 38 milliseconds|
Think, Act| 340 +- 62 milliseconds| 323 +- 50 milliseconds| Read, Think, Act| 422+- 124 milliseconds| 414 +- 119 milliseconds| Read,
Think-Negate, Act| 398+- 102 milliseconds| 375 +- 102 milliseconds | Test Type| Control Experiment| Experiment w/ Caffeine|

Act | 372 +- 70 milliseconds| 361+- 67 milliseconds|
Think, Act| 321 +- 49 milliseconds| 310 +- 46 milliseconds| Read, Think, Act| 398+- 76 milliseconds| 391 +- 74 milliseconds| Read, Think-Negate, Act| 394+- 106 milliseconds| 370 +- 68 milliseconds |

*The data shown are the averages of 10 trials that was calculated by the serendip program *The data shown are the averages of 10 trials that was calculated by the serendip program Keon Shim, 39, Male

Keon Shim, 39, Male
Mi Ok Kim, 44, Female
Mi Ok Kim, 44, Female

7) Analyze the data and observations

7) Cont.

Analysis: The results we received from the experiment were what we had suspected. For every test subject, the reaction times for every “Case” that were influenced by the coffee’s caffeine were quicker than the controlled reaction times. For example, Daniel Kim had a controlled “Read, Think-Negate, Act” average reaction time of 375+-102 milliseconds. When he consumed the 12 oz of coffee, his average reaction time decreased to 344+-60 milliseconds.

It is quite apparent from the graphs that the average reaction time for every “case” for each test subject decreased when absorbing caffeine into their system. Test subjects also consumed the “right” amount of caffine, 160mg, which allowed the subject to shorten their reaction time, while the wrong dosage could impair it. We can also draw from the graphs the relation that the younger the test subjects are, the quicker their reaction time will be. Also, we can also conclude from the results that males tend to have a quicker reaction time than females (Daniel’s reaction times were faster than Jazmine’s, and Keon’s were faster than Mi’s).

8) State the conclusion

The hypothesis was correct. The effects of caffeine shortened the reaction time in all of our test subjects.

9) Summary Paragraph

The reason why we were able to correctly devise a hypothesis for the experiment was because of the prior knowledge we had of the drug, caffeine. Caffeine increases the heart rate, which allows for faster muscle contractions. Caffeine does not really affect the actual reaction of the nervous system, but rather the actual contractions of the muscles themselves. This known fact of caffeine is reflected in the experiment. It shortened the reaction time of our test subjects in every “case”. We found other factors in our experiment that may have affected the reaction time of our test subjects. A few scientists have theorized that gender can affect reaction time.

They say that males tend to have a faster reaction time because males are usually involved in more physical activities, such as sports, which helps improve reaction time. That “theory” is also reflected in our results. All the male subjects had faster reaction times than their age equivalent female subjects. Finally, the last factor would be the age of the test subject. Our younger test subjects both had faster reaction times than both the older test subjects. There are many theories being circulated that once someone enters their mid-twenties, their reaction time slowly increases.

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