Does Having a Cell Phone Conversation Affect Reaction Time While Driving?

Introduction: Although several states have placed restrictions on cell phone use while driving, it's still not uncommon to see drivers with one hand on the wheel and the other hand holding their cellular phone. Is using a cell phone while driving enough of a distraction to make a driver dangerous?

People who use cell phones while driving are as impaired as drunk drivers, according to a recent study conducted by the University of Utah (Reuters). Even if a hands-free device is used, a person's driving ability is significantly affected because their reaction time is significantly slowed down. According to the study, drunk drivers and cell phone users alike did not believe themselves to be affected when their reaction times were in fact impaired.

Hypothesis: My hypothesis is that participants will perform better on the reaction time test when they are fully focused, simulating an undistracted driving experience. When the participants are distracted through being engaged in a conversation and simulating a cell phone conversation while driving, I believe their reaction times will be significantly slowed.

Materials and Methods:The researchers at the University of Utah used a simulated driving machine to test the study's participants, but reaction time can be measured easily at home with simpler supplies. In my experiment, I measured reaction time with nothing but a ruler.

I had each participant hold out his or her thumb and forefinger. I had my helper hold a ruler just above their fingers. When my helper dropped the ruler straight down, the participant grabbed the ruler as fast as they could between their thumb and forefinger. The participant received no prior warning.

I tested eight participants, all adults with driving experience. Each adult was tested through six trials. During the first three trials, the participant was undistracted and focused on grabbing the ruler quickly. These trials simulated driving without any diversions. In the final three trials, each participant was engaged in a conversation with my helper while simultaneously trying to focus on grabbing the ruler. These trials simulated driving while using a cell phone and being forced to split one's focus between two tasks.

The place (in inches) where the participant grabbed the ruler can be converted into their reaction time in milliseconds using the following table ("Human Behavior"). SEE TABLE A.

Results: Each subject was tested using six trials. The first three trials were run without distraction of any type. The final three trials were run while my helper engaged the subject in conversation to simulate a cell phone conversation. SEE TABLE B.

Discussion: We can respond to a visual sensory stimulus in 150 milliseconds under optimal conditions, according to sciencebuddies.org. Taking much longer to respond to stimuli can prove dangerous in situations such as driving, especially if more time is needed to choose between two or more choices of behavior. For the purposes within my experiment, I judged driving ability to be impaired if the subject took longer than 180 milliseconds (more than 6.5 inches of dropping distance) to respond to the visual stimuli. 180 milliseconds is adequate time to respond to a visual cue and make quick decisions if necessary ("Human Behavior").

Seven of the eight participants proved my hypothesis to be correct. Their performances were exactly what I predicted. Each of them was able to react quickly without distraction during the first three trials. This showed that their reaction time was perfectly safe for activities such as driving. During the final three trials, their reaction times were not as reliable. This shows that any distraction, such as the use of a cell phone, will slow a driver's reaction time and affect the driver's safety on the road.

The participant who performed differently than predicted (Subject 7) may have been affected by other factors. He could have felt distracted throughout the entire experiment, even though I minimized distractions during the first three trials. He also could have felt anxious about his performance and allowed his nerves to slow his reaction time. Finally, his reaction time could have just been naturally slower than the other participants. Because only one of the participants was affected in this way, I do not think that there was an error in my experiment. I think that the discrepancy should be contributed to the participant, not to the experiment itself.

Conclusion: Because of the results I gathered through my experiment, I believe that using a cell phone is significantly distracting to drivers. Using a cell phone distracts a driver and slows their reaction time, which can be very dangerous on the road. When a driver is fully focused on safe driving, reaction times are much faster and driving is much safer.