Danger is calling. Will you answer?

Science Fair 2014-15 Madison Olney

Back Ground Research

What happens if you are taking a call on your cell while driving? Do you focus on your surroundings as well as you are the conversation you’re having? This study will investigate how you having a cell conversation hands-on, hands-free, or not at all effects your reaction time, and if it is best not to talk on a cell while driving.

Reaction time is the time that elapses between a sensory stimulus and the response to that stimulus. Thus, it is a measure of the total time necessary for a chain of internal events:

· The stimulus activates one or more sensory receptors,

· The receptor(s) send a signal to the central nervous system (CNS),

· The CNS processes the incoming signal and elicits a neural response,

· Which must then travel to the appropriate muscles in order to generate the physical response.

"Under optimal conditions of attention, we can respond to a sensory stimulus in 120 to 150 ms." (Ghez, 1991) So I wonder if you’re on you cell phone, does it serve as a distractor? Causing your reaction to slow? If so, talking on the phone could be an optimal condition, which could increase our speed and reaction time, if your reaction time is slower when on the phone, your braking distance would increase resulting in possible crashes and accidents on the road. When you pick up the phone, do you put your life on the line?


The goal of this project is to determine whether or not engaging in a cell phone conversation adversely affects reaction time.


It is predicted that the subject’s reaction time when concentrated exclusively on reaction time test will be faster than the subject’s reaction while having a cell phone conversation, both hands-free and hands-on because in the hands-free and hands-on trials the cell phone serves as a distractor.


1. dependent variable -- how long the reaction time is

2. independent variable – talking on the phone

3. control group – while the subject is concentrating only on catching the ruler

4. experimental group – hands-on, and hands-free scenario


1. Cell phone- with hands-free operation mode

2. An assistant to converse with subjects on phone

3. List of questions and topics for cell phone conversations

4. Yard or meter stick to conduct reaction time


  1. Do your background research.
  2. Prepare a list of questions and topics for engaging your subjects in conversation.
  • Keep in mind that your assistant will need to keep a conversation going with each subject during multiple trials. Make sure your assistant gets some practice asking questions with a different group of subjects, so that you can refine the list of conversation topics.
  1. Prepare the test of reaction time. Verify the number of trials required to assure consistent results.
  • A simple method for measuring reaction time is to have the subject grab a ruler as you drop it. Perform a pilot study (with a separate group of subjects) to determine how many trials you need to get a consistent measure of reaction time. This is the number of measurements you will need to make for each of the trials in your experiment. A yard stick is recommended. Make sure that you use consistent sensory cues each time you drop the ruler. For example, if you give the subject an auditory cue ("Go!"), then be sure to give it each time, and in the same way.
  1. Recruit your volunteers and run the tests.
  • You will need to test a sufficient number of subjects to assure that your results are statistically significant... Keep the experimental conditions the same for all subjects.
  • You will test your subjects' reaction time during each of three conditions:
  • while the subject is talking with your assistant on a hands-free cell phone,
  • while the subject is talking with your assistant on a hands-on cell phone,
  • While the subject is concentrating exclusively on the reaction-time test (control).
  • You should use at least 25 subjects and conduct two trials per the conditions above. Note the experimental conditions and record the results of each trial, along with any observations you make during the experiment. It will help to organize your results in a table. Make sure that your experimental conditions are as consistent as possible. For example, you should always use the same assistant to carry out the phone conversations. Age group could span anywhere from new drivers to early 20 yr. old and 30 yr. old drivers.
  1. Analyze the results.
  • Average the results for each participant.
  • Think about how to compare results between participants or the conditions to each other. Here are some possibilities. You could simply average results for each of the three conditions, but if your subjects' normal reaction times vary significantly, then averaging could obscure your results. You could calculate the average difference in reaction time between the control and experimental conditions for each subject, and then average this number across all subjects for each condition.
  1. Analyze the statistical significance of your results. Formulate the null hypothesis against which you are comparing your results.
  • What is the probability that your results could be explained by the null hypothesis?
  1. Prepare one or more graphs to present your results.
  • If you do find a difference in reaction time, an interesting graph might be to show what the change in reaction time translates to in terms of stopping distance for a car traveling at different speeds.


The subjects seem to be faster with the hand-free scenario, (where the cell conversation isn’t serving as a distractor). Also many subjects told me they observed that when I gave them the auditory cue, “Go,” was startling and not expected. Which they said simulated the feeling of the moments before you realize you’re about to crash into another vehicle. Some people weren’t very engaged in their cell conversation. Others were too engaged and didn’t perform as well even when they were asked the same questions. So I observed that some people are got unawares more than others.

Data / Statistical analysis

After Experimentation


Claim- I observed that the participants preformed significantly worse when a cell phone was in use, compared to when they focused completely on hearing the auditory cue, “Go”.

Evidence- Evidence shows when looking at my total averages of the three scenarios they showed that the reaction time in seconds increased from 0.22 when not talking on the phone to 0.31 when using a hands-free option on the phone to 0.34 when talking normally on the phone. This represents a 41% increase in reaction time when talking on the phone with a hands-free mode and a 55% increase in reaction time when talking regularly on a cell device. The student T-Test proves that these differences in reaction time are highly statistically significant.

Reasoning- The results were what they were because the cell phone served as a distractor to the subject. This is why the scenario where no cell phone was used had a higher average reaction time. This is also why there was a slight improvement between the hands-on and hands-free reaction times, with the reaction time of hands-free being a little smaller than hands-on because being on a speaker eliminates having to hold the phone up to your ear as well as carrying a conversation.


The trends in my data support my hypothesis and claim that my subjects preformed significantly worse when a cell phone was in use, compared to when they focused completely on hearing the auditory cue, “Go”. So this proves that a cell phone can slow your reaction time.

Sources of error and Inaccuracies

Some sources of error could measurement, which occurred when the subjects would catch the ruler and there hand was too wide too tell exactly what inch or inch and a half they caught the ruler at. Another Inaccuracy could include the level of questioning the questions we asked each individual. Because obviously more rigorous questions take all their concentration, while less rigorous questions allow them to listen for the auditory cue more. Or yet another inaccuracy could include whether the participant was standing or sitting during testing.


This experiment applies to real life with driving. Being on your phone slows your reaction time, when I drop the ruler, and your reaction time while driving on the road. You can take my results and conclude that it is crucial NOT to use your phone on the road. Because if your reaction time is slower when on the phone, your braking distance would increase resulting in probable crashes and accidents on the road. By knowing this hopefully it will influence your decisions about what you do on the road, and prevent those probable incidents.


I could improve the fact that, the subjects would catch the ruler and there hand was too wide too tell exactly what inch or inch and a half they caught the ruler at, by having the subject catch the ruler with their forefinger and thumb. I could easily fixing the leveling of questioning and stance while testing problems by following my own procedure and make sure that all aspects of the testing environment stay the same.


  • “American Psychological Association (APA)”.http://www.apa.org@2014AmericanPsychological. web.26.spt.2014. cal.Ass.n.d.

  • BBC.”Thinking, Braking and Stopping Distance” BBC News. BBC, June 2, 2011, web. 25 sept. 2014

  • Ghez, C., 1991. "Voluntary Movement," in Kandel, E., J.H. Schwarz and T.M. Jessell. Principles of Neural Science: Third Edition. Norwalk, CT: Appleton & Lange.
    Goldrich, A.M., 2004.

  • Moore, Thomas Verner.Pg.17.”A Study In Reaction Time and movement” New York: Random, 1992.