The Effect of Cellular Telephone Usage on Reaction Time
There are over 105 million cellular phones in the United States today, including 32% of all teenagers. Some surveys have shown that 85% of drivers often use their cell phones while driving, which increases their risk of collision four times. The purpose of this project was to determine the effects of cellular telephone usage on reaction time. Eighty teenagers (15-18) and 80 adults (age 24-60) were each divided into control and experimental groups. Two tests were taken: a computerized reaction test with random dots appearing within a thirty-second time period and a foot reaction timer measuring the response to a light stimulus. The experimental groups were engaged in conversation on a cell phone during the two tests. The phone conversation increased reaction time for all groups. The teens had better reaction times on both tests than the adults. Eighteen t-tests were done to compare different groupings. All were significant, except the teenager groups on the computer game and the difference between female teenagers and female adults on reaction timer. The results of this study seem to indicate that cellular telephone usage does have an effect on reaction times.
Cellular phones were introduced in 1983, and usage has exploded to more than 105 million phones in the United States. (1) Included in this number is a growing percentage of teenage users—about 32% of the age group at the end of 2000. (2) Cell phones are used in many places, but use by automobile drivers is a particular concern. More and more drivers are using commute time to conduct business and personal affairs on phones. A recent survey by Prevention Magazine found that 85% of cellular telephone users polled said they often use their phones while driving. (3)
It is a great way to make good use of time, but there is a down side. The risk of collision when using a cell phone is four times higher than when one is not in use. (4) One study estimates that a driver on a cell phone has a 6-in-1 million chance of dying in an accident each year. Last year 27 states considered cell phone legislation—either banning while driving or using hand-free devices. (5) Fourteen other countries now restrict the use of cell phones in cars. (6)
Accidents often happen when a person is distracted. Dialing, discussing, and holding a conversation affect a person’s ability to properly respond to typical driving situations. The interference of making a telephone call while driving a vehicle is primarily visual and mechanical and has to do with seeing, locating, and punching the keys. (6) The distraction that results from carrying on a conversation is largely cognitive and is greatly influenced by the nature of the conversation itself and the amount of attention it demands. (7) An intense business conversation could divert a driver’s attention so that signs of danger may be overlooked. A survey of cellular phone users showed that on the average 72% of all conversations are for business purposes. (7) However, casual social conversation may be no more distracting than talking to a passenger. Less-experienced drivers may be particularly affected by distractions because as a group they have higher accident rates than most adult drivers. (8)
Reaction time is a very important factor in driving situations. Reaction time is the time from the onset of a stimulus to the beginning of the response. (9) The foreperiod -- the time a subject waits for the stimulus -- may be constant or variable; when driving, it varies. More intense stimuli lead to faster reaction times. Auditory stimuli lead to slightly faster reaction times than visual stimuli. Reaction time tends to slow with aging, and males tend to have faster reaction times than females at all ages. (10) Types of reactions include simple and choice. Simple involves one stimulus and one response. Choice occurs with more than one stimulus, and more than one response is produced. Also, practice reduces reaction time. Driving situations involve different types of stimuli and responses. Accident report data shows that car phone users tend to swerve out of the lane or hit something in front of them. (6)
The purpose of this project was to determine the effects of cellular telephone usage on reaction time. Because it was believed that cellular phone usage would increase the time of reaction to visual stimuli and that adult phone users would have slower reaction times than teenagers, three null hypotheses were developed. First, talking on a cell phone does not affect the hand reaction time to visual stimuli for a particular age and gender group. Second, talking on a cell phone does not affect the foot reaction time to visual stimuli for a particular age and gender group. Third, there is no difference between the mean reaction times of teenagers and adults to visual stimuli when talking on a cell phone.
Materials included a computer with Internet access, a reaction timer, a cellular phone, a phone in a different room than the subject, and permission slips.
Test subjects were grouped into 15-18 year-olds and adults ranging in age from 24 to 60 years of age. First, each test subject sat at the computer and played the hit-the-dot game from “Brain Games” on the Internet. As the thirty-second game progressed, the subject clicked the mouse on the dot as it appeared randomly. The number of dots hit within the thirty-second time period was recorded. For the second test, the test subject put his or her right foot over the reaction timer foot switch and pressed it in response to the light stimulus. The time of response was recorded. Eighty test subjects constituted the control group, twenty 15-18 year old females, twenty 15-18 year-old males, twenty adult females, and twenty adult males.
Eighty different test subjects repeated both the hit-the-dot game and the response to light with the reaction timer while engaged in conversation with the researcher on the phone. Each subject responded to the following prepared set of questions:
1) What did you have for dinner last night?
2) What did you get for Christmas?
3) What is your favorite movie?
4) What is your favorite color?
5) Where’d you get your shirt?
6) What did you have for lunch?
7) Tell me how to get to your house from the school.
DISCUSSION OF RESULTS
When the phone group scores were compared to the control group scores for the computer game, involving hand reaction time, the control group results were higher for all teen, adult, male, and female comparisons. The results for comparisons among the same groups for the foot reaction timer were the same, with the phone conversation increasing the time of response. When the teen phone was compared to the adult phone, the teen scores were higher than the adults on the computer game Comparison among the same groups for the foot reaction timer showed the adults having slower reaction times than the teenagers for both male and female groups.
Eighteen t-Tests were done to compare the results while on the phone to the control group and to compare the results of teenagers engaged in conversation to the results of the adults engaged in conversation. Significance was shown for all groups except: both male and female 15-18 year-olds compared to their control groups on the computer game, female 15-18 year-old phone results to female adult phone use on the reaction timer, and the combined group of all 15-18 year-olds compared to their control group on the computer game.
The phone conversation increased reaction times and decreased scores for the computer game for all groups. The lack of significance shown by the t-Tests comparing all teenagers engaged in conversation to their control group indicates that teens are not as easily distracted by phone usage as adults. Previous research has shown that aging increases reaction times. Scientists have speculated the reason for slowing reaction time with age may be the tendency of older people to be more careful and monitor their responses more thoroughly.
The results of this study seem to indicate that cellular telephone usage does have an effect on reaction times. Talking on a cell phone does affect the hand reaction time to visual stimuli for the adult male and female comparisons of phone to control and male and female comparisons of 15-18 phone to adult phone. Talking on a cell phone does affect the foot reaction time to visual stimuli for all groups except the female 15-18 phone to adult phone group. There was a difference between the mean hand reaction times of teenagers and adults to visual stimuli while talking on a cell phone for combined groups. All null hypotheses were rejected.
Future work could be done by not only testing cognitive effects of conversation but, also the mechanical effects the have to do with seeing, locating, punching the keys, and answering the phone. This may be done by using driving simulators.
1) Daily Oklahoman – Etiquette Eludes Cell Phone User – Jan. 2, 2001
2) Daily Oklahoman – Drop in Teen Smoking – November 3, 2000
4) http://www.aloha.net/~dyc/distracted.html, 11/3/00
5) Daily Oklahoman – Ford Announces $10 Million to Test Driving – Jan. 11, 2001
6) Spencer, Paula (2000). Driving to Distractions. Women’s Day, September 12, 2000, pp. 105-108.