Effect of Car Phone Usage on Cognitive Ability and Driving Performance

Kevin Bogle

Classen School of Advanced Studies

Oklahoma City, Oklahoma

Abstract

Controversy is sharp regarding car phone use while driving. Dangers may include reduced competence and difficulty in concentration. The following research question was developed: Can drivers successfully drive safely and simultaneously use a car phone? Three studies were conducted to determine driving performance and cognitive ability while driving with and without a car phone. Experiment 1 used 45 participants on a driving simulation; Experiment 2 tested 20 and Experiment 3 tested 25 drivers on three driving tasks: serpentine forwards and backwards; parallel park; and a driving course. Drivers in all three studies completed the course: once while using no phone, once using a regular car phone, and in Experiment 3, once with a hands free phone. Order of conditions was counterbalanced. Three equivalent lists of groceries and directions were used to test cognitive ability. A t-test or analysis of variance for repeated measures was performed on all five measures of driving performance and cognition. Analyses revealed that statistically significant differences exist (p < 0.0001), indicating car phone use adversely affected driving performance and cognitive ability. Drivers were largely unaware of their impaired performance. The results clearly indicate car phone use is dangerous and caution should be used.


 

Effect of Car Phone Usage on Cognitive Ability and Driving Performance

            Many drivers talk on their cellular phones or on car phones while they are driving. However, there currently exists a controversy about whether car phone usage while driving should be allowed. Some claim that it is safe and a matter of personal choice; therefore, car phone usage should not be prohibited by legislation. Others contend that the use of car phones  is unsafe, dangerous, and that its use should be prohibited by legislation. Car phones may cause problems by reducing competence and concentration. However, prior research has not yet clearly determined if talking while driving harms one’s ability to drive safely.

            Research in related areas has shown that it is difficult for humans to do more than one thing at a time if the tasks require cognitive processing, such as listening to two messages at the same time or processing two visual images at the same time. Some tasks that initially required significant cognitive processing have been shown to become almost automatic, therefore, not requiring as much attention and focus on the task, for example, typing, CPR, reading, and driving. As these skills are mastered they require less cognitive processing which allows one to be able to do some other things at the same time (Solso, 1999).

            Police officers claim that many accidents are caused by drivers not paying close attention to their driving while they are talking on their car phones. Police report that drivers cannot safely do both things at the same time. However, no systematic experimental research has, thus far been conducted to address this very important issue. Therefore, the following research question was developed: Can drivers successfully do two things at the same time-- drive safely and simultaneously use a car phone?

            Limited research has been conducted to address the issue of reduced competence and concentration while driving. The National Highway Safety Administration (1997) and the New England Journal of Medicine (Redelmeier & Tibshirani, 1997) cite frequency of car wrecks while

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using cellular phones as evidence that car phones are dangerous. Ridley (1998) demonstrated that using only one hand to drive may impair performance. Recently, it was reported in the Dallas Morning News (2000) that a 43-year-old Irving man died after losing control of his vehicle. Traffic investigators on the scene thought that the man “was distracted by his car phone.” Redelmeier & Tibshirani (1997) examined the phone usage logs of 700 drivers who had been involved in traffic accidents. The risk of accident was four times greater for drivers who had used their car phones five minutes before their accident occurred. But, it is not known whether the drivers were actually on the phone talking when the accidents occurred or if talking on the phone in any way caused the accidents. None of these studies have reported experimental research.

             In spite of the negative charges, most car phone manufacturers claim that phone usage while driving is completely safe. AT&T wireless recently contracted with the Harvard Center of Risk Analysis (Lissy, 2000) to interview cell phone users regarding their use of phones while driving. Their results revealed that 80-90% of cell phone owners use their phones while driving. The drivers surveyed did not think that their driving was impaired by cell phone usage, and they thought that the benefits of greater time productivity and “social networking” outweighed any risks (Lissy, 2000). However, it is important to note that no experimental research was conducted, nor was driving ability measured.

            In the United States, the controversy is sharp. Many citizens feel that they should have the right to use car phones, no matter what the risk. They consider it a personal freedom. In a few counties in the U. S., such as Marlboro in New Jersey, Brooklyn in Ohio, and Lebanon in Pennsylvania, car phone usage has been prohibited (Dotinga, 2000). No states have passed similar restrictive legislation to date, although Arkansas has a bill under consideration. World wide, 13 countries including Australia, England, France, Germany, Italy, Japan, Portugal, Sweden, Spain, and Switzerland have banned or restricted cell-phone usage in cars-- drivers must pull off the road to use their car phones even in an emergency (Ebersole, 2000).

            Research clearly indicates that people have difficulty processing information from more than one source at a time (Solso,1995; Sternberg, 1996). For example, Cherry (1953)  demonstrated that people cannot process information from two auditory inputs simultaneously. Using earphones, Cherry had participants listen to two different messages in each ear while shadowing the message in one ear or the other–surprisingly little information could be processed from the unattended ear. Moray (1959) included subject’s names in the unattended ear and they were able to process this, but little else. Similarly, Neisser & Becklen (1975) demonstrated that people cannot process two visual inputs at the same time. When participants were shown two superimposed videotapes simultaneously and asked to follow the action in one of the films, very little information from the unattended film was processed. People are apparently unable to process two things in the same modality simultaneously.

            Posner (1988) showed that while some parts of the cortex are involved in attention, other parts of the cortex are involved in information processing. When attention is focused on a foveal task, participants are unable to discriminate relevant from irrelevant distractions in the periphery (de Fockert, Rees, Frith, & Lavie, 2001).

            Additionally, LaBerge (1975) and Tulving (1989) demonstrated that although some tasks initially require significant attention to the task, they can become somewhat automatic through time, requiring less cognitive processing. Such tasks include typing, playing a musical instrument, scuba diving, reading, and driving. Initially, it requires all one’s available attention just to be able to perform the task; finally, the motor skills involved become relatively automatic.

            After driving becomes more automatic, how much cognitive processing can be performed while driving? If someone is driving, listening to the radio, and also talking on a car phone, how much is his/her driving ability jeopardized? Although there has been significant discussion regarding the use of car phones, the accuracy, speed, and safety of drivers, both with and without using car phones, has not been experimentally tested. The question remains: how does a normal driver react when using a car phone? Three current investigations were designed to use drivers in both simulated and realistic driving situations. Would drivers be able to drive as quickly and efficiently with the car phone as without it and would drivers be able to remember simple driving instructions and groceries, as well with the car phone as without it?

Experiment 1- Driving Simulation

Method

            Participants. Thirty-five students from University of Central Oklahoma volunteered to participate: 8 females and 17 males. All were experienced drivers with an average age was 29 years. All were treated in accordance with APA guidelines for use of human participants.

            Materials. Participants in a pilot study tested four different games: Screamer II, Road Rally, Championship, and Need for Speed II. The last program was chosen as the most realistic because it allowed oncoming traffic, similar road signs, and weather conditions. A steering wheel with controls for gears and horn was used. Additionally, pedals for acceleration and for braking were installed and used. These added to the realism of the driving situation. A radio was placed beside the test site because most of the participants indicated that they normally listened to the radio in the car. A car phone was placed beside the computer simulation to be used during one of the two 5-6 minute laps around the course.

            Procedure. Participants turned the radio to their typical station and were given a list (eight items) of groceries and directions (eight items) to remember. Each was given instructions for how to drive using the steering wheel, how to accelerate and brake using the foot pedals, how to honk the horn, and how to reverse. Each participant then practiced a lap around the course to get used to the equipment. Participants were then asked to recall the groceries and the directions. The participants then drove the course twice, once while using the car phone and once without it. The order of conditions was counterbalanced to minimize practice effects.

Results and Discussion

            The number of mistakes made for the two conditions (with and without car phone) were compared for four measures: 1) time taken to complete the lap; 2) number of times the driver swerved out of his/her lane; 3) number of times the driver hit signs, or trees or left the road; and 4) number of times the vehicle crashed. The scores for all four measures with and without phone were averaged (Table 1, summary of statistical results including means and t values.).

            All the measures used in the first study indicated double or triple the number of errors during the simulated driving. People reported that talking on the car phone helped them concentrate better and stay more focused. They were completely unaware of their errors. This is an especially important finding because it indicates that the use of car phones may be particularly hazardous. Not only was the simulated driving debilitated, and concentration impaired, but the drivers were unaware of both types of shortcomings. It appears from these results that this is an instance of human cognitive functioning being overloaded beyond capacity (Figure 1-2). It was obvious that the actual driving performance of drivers was important to test experimentally.

Experiment 2 - Driving Course

Hypotheses

            The simulation study provided preliminary findings that car phone conversation requires sufficient cognitive processing to negatively affect driving performance. Based upon the findings of the simulation study, the following hypotheses were developed for the second study which involved drivers behind the wheel of actual vehicles: (1) Drivers will remember a grocery list significantly less well when using a car phone than when not using a car phone; (2) Drivers will remember directions to a location significantly less well when using a car phone than when not using a car phone; (3) Drivers will drive significantly more slowly when using a car phone than when not using a car phone; (4) Drivers will make significantly more mistakes and drive significantly more reckless when using a car phone than when not using a car phone; and

(5) Drivers will parallel park significantly worse when using a car phone than when not using a car phone.

Method

            Participants. Twenty college students from the University of Central Oklahoma, different from Experiment 1, volunteered to participate in the study. There were ten females and ten males. Their ages ranged from 16-46; the average age was 28 (females-29; males-27). Driving experience ranged from 6 months to 30 years; the average number of driving years was 12 (females-13; males-11). One-third of both male and female drivers were regular car phone users. The participants were tested individually, thanked for their participation, and then debriefed.

            Materials. In order to test how drivers would perform both with and without talking on a car phone, it was important to develop realistic driving challenges. The university driving course, used in its driver education program, was adapted. Three driving tasks were developed. First was a serpentine task, followed by a driving course task, and then a parallel parking task. All drivers were asked to drive their own vehicles because they would be familiar with the vehicle and would be adequately insured. A cellular telephone was placed beside the driver to be used during one of the two laps around the course and one time while parked.

            Two equivalent lists of groceries with eight items each had been previously developed for use in the simulation experiment. Each list contained eight items. Also, two lists of directions which had been previously developed were used. The directions were equal in difficulty with the same number of elements (eight) to be remembered. The list and directions were used in the previous driving simulation experiment.

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            Other materials included a car phone, stopwatch, pencils, data sheets, and forms for the drivers to write down the groceries and directions they could recall. Standard equipment was used such as counters to measure inertia and tumblers to measure accuracy and jerkiness of movement.

            Procedure. First, each student was seated at the steering wheel and if he/she normally listen to music when driving, tuned in his/her favorite radio station. The researcher sat in the back seat in order to give instructions, to observe the driving performance, and record data. An additional assistant sat inside a nearby building in order to call the driver on the car phone at the appropriate time.

            The driver was then given a list of eight grocery items and directions to someone’s house. Each student repeated each item and each segment of directions after the assistant read them. Next, the participant was given instructions for his/her first task. After instruction, the participants were asked to recall the groceries and the directions. For the serpentine task, drivers were asked to drive forward around three cones set in a straight line, and finish with the center of the front of the car as close as possible to the last cone. They were then asked to drive backwards around the cones and center the back of their vehicle against the last cone. The number of cones touched and the number of inches off center were measured.

            Next, was the driving course. Drivers were told that both speed and accuracy would be recorded. They drove the course twice, which included driving off the road momentarily, around a “cone” car, around a curve, over a hill, around a figure eight, across the “highway,” over a railroad track, and back to the starting point. Standard equipment was used to measure driving accuracy–the number of weights which tipped over and the number of changes in inertia measured by a counter were recorded. In addition, the time it took to complete the course was recorded.         The third task entailed parallel parking in a designated spot. How centered the vehicle was, how many inches from the curb, and how long they took to park, were all recorded.

            Each driver completed all three tasks, both with and without talking on the car phone. The order of the conditions was counterbalanced: for half the participants, driving with no phone was their first condition, followed by talking on the phone next; for the other half, the condition with talking on the phone was first, followed by no phone for their second condition.

            During the lap when the car phone was used, the phone rang at the beginning of the lap and conversation continued throughout. An assistant provided the participant with an equivalent grocery list, and an equivalent set of directions to remember. After the directions were given, the participant was engaged in conversation about his/her birth, age, siblings, parents, places of residence, date and location of high school graduation, number of hours finished in college, and classes planned for the upcoming semester. After the driving course was completed, the participants recalled as many groceries and directions as they could. The amount of time between being given the list and being asked to recall the list was held constant for both conditions. The experiment took about an hour for each participant after which the purpose of the experiment was explained.

Results

            Scoring. There were six comparisons made. The number of correctly remembered grocery items and the number of correctly remembered directions were recorded for both conditions: with and without the car phone. Next, the errors made for the two conditions (with and without car phone) for four measures: 1) score on the Serpentine task (number of cones hit and inches off center of the cone); 2) time taken to complete the course; 3) score on the driving course (number of tumblers fallen plus number on the inertia counter); and 4) score on the parallel parking (whether the driver signaled plus number of inches the vehicle was from the curb). The scores for all four measures, with and without phone, were averaged and t-tests for correlated measures were performed on the data.

            Analyses. For the number of items recalled on the grocery lists, the drivers averaged 5.5 grocery items without driving and 2.63 number of items recalled while driving. This was a statistically significant difference using a t-test for repeated measures (t (19) = 9.04; p< 0.00001). For the number of correctly recalled direction items without the phone averaged 6.94 and 2.95 directions recalled with the phone while driving. This was a statistically significant difference using a t-test for repeated measures (t (19) = 11.92; p< 0.00001, Figure 3 ).

            The students averaged 54.03 on the serpentine task without talking on the phone and 103.75 on the serpentine task while talking on the phone (number of cones hit plus number of inches off center). This difference was statistically significant using a t-test for repeated measures (t (19) = 4.81; p< 0.0001). The students in this study averaged 3.12 minutes per lap without the phone and 3.51 while talking on the phone. A t-test for repeated measures performed on the data (t (19) = 6.44; p < 0.00001) indicated that the lap without the phone took less time; this difference was significant. Students averaged 20.35 on the driving course score (number of tumblers fallen plus number of counters moved) without the phone and they averaged 31.0 with the phone being used. This was a statistically significant difference using a t-test for repeated measures (t (19) = 4.81; p < 0.0001, Table 2).

            Finally, on the parallel parking task (signaling + number of inches from curb), the students averaged 22.63 without talking on the phone; 40.35 while talking on the phone---a statistically significant difference using a t-test for repeated measures (t (19) = 2.36; p< 0.0292, Figure 4).

Experiment 3-Hands-Free Car Phone

Method

            Participants. Twenty additional students from University of Central Oklahoma volunteered to participate: 12 females and 8 males. Their average age was 29 years. All were experienced drivers; the youngest driver had been driving over four years and the oldest driver had been driving for over 30 years. Almost half of the participants were regular car phone users.

            Materials.  The materials used in Experiment 3 were the same as in Experiment 2, except that a third equivalent list of groceries and set of directions of equal difficulty were developed. Care was taken that items were similar but not so similar as to cause confusions within categories, such as that seen with retroactive interference (Wickens, 1970, Wickens, Born, & Allen,1963).

            Two types of car phones were used. The first was a regular car phone that was held in the hand. The phone was similar to, but smaller than, a regular land-based phone. A hands-free phone was used for the third condition. This phone was installed in the car with a speaker on the base for listening and a small speaker to pick up voices attached to the sun visor. All the driver had to do was to push one button to answer and one button to end conversation.

            Procedure. The basic procedure used in Experiment 3 was the same as in Experiment 2.  Participants first performed a serpentine tasks both forward and serpentine backward and were measured on how close to the cone and how many inches off center they drove. Next, they drove the course, which included cones as “vehicles” around which the participants had to serpentine.  Number of cones hit, tumblers felled, or weights knocked over were recorded as well as their driving speed. Finally, participants parallel parked, and the number of inches from the curb and inches off center were tabulated for all three phone conditions. They were also timed on this task. Participants were required to memorize the grocery items and the directions. The amount of time required before recall was consistent between all three conditions.

Results

            Scoring. One factor within-subjects analyses of variance were performed on the data for each of the five dependent variables. The number of correctly remembered grocery items and the number of correctly remembered directions were recorded for all three conditions: without a car

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phone; with a regular car phone; and with the hands-free car phone. Next, the mistakes made for the three conditions for three measures: 1) score on the Serpentine task (number of cones hit and inches off center of the cone); 2) time taken to complete the course; and 3) score on the parallel parking (whether the driver signaled plus number of inches the vehicle was from the curb and if the car was centered in the space. The scores for all measures, during all three conditions, were computed and analyses of variance for repeated measures were performed on the data.

            Analyses. Statistically significant results were obtained for all the dependent variables. For the number of items recalled on the grocery lists, the students averaged 5.55 grocery items with no phone, 3.95 with a regular car phone, and 2.8 recalled while driving with a hands-free car phone (F (2, 18) = 15.96; p < 0.0001). Similarly, the average number of directions recalled with no phone was 5.3, and 3.4 for both types of car phones (F (2, 18) = 14. 50; p < 0.0002). The Bonferroni t-test was used to determine which means differed from each other. The analyses revealed statistically significant differences between no phone and both of the two phone conditions, but they did not differ from each other (Table 3).

            For the serpentine task, the students averaged 24.6 inches off goal for the no phone condition; 41.9 for the regular car phone, and 45.2 for the hands-free phone. These differences were significant (F (2, 18) = 6.38; p < 0.0081). For the total time in seconds the drivers averaged 185.7 for the no phone condition, 234.7 for the regular car phone, and 229.0 for the hands-free phone. These differences were also statistically significant (F (2, 18) = 13.32; p < 0.0003). Finally, the parallel parking errors were recorded in inches. The drivers averaged 24.6 with no phone, 41.9 for the regular car phone, and 45.2 for the hands-free phone. These differences were statistically significant as well (F (2, 18) = 3.82; p < 0.0415). Bonferonni t-tests revealed for all comparisons that the no phone condition was significantly different from the two phone conditions; however, the two phone conditions didn’t differ from each other (Table 3).

Conclusion

            The experimental question which was developed for the research was: Can drivers successfully do two things at the same time--drive safely and simultaneously use a car phone? All three experiments measured the effect of car phone use on the speed, accuracy, and performance of drivers. The data showed that both the driving performance and cognitive performance was significantly negatively affected.

            According to all measures, participants drove statistically significantly worse when using the car phone. All the data collected indicated double or triple the number of errors while driving. Participants’ speed, accuracy on serpentine and parallel parking tasks, and precision on the driving course were significantly impaired when they were talking on the phone compared to when they were not. Even the speed at which the course was completed was negatively affected. These findings are consistent with the findings of Redelmeier & Tibshirani (1997), who reported car phone users are four times more likely to be involved in an accident.

            Additionally, the cognitive ability of participants to remember grocery items and directions was significantly impaired. When the drivers were not on the phone, the number of items correctly recalled was 5-6 items, which was a reasonable expectation (i.e., 7+2, Miller, 1956). But, they were only able to remember about half that amount of information when they were talking on a car phone. The tasks which involved mental concentration were significantly jeopardized.

            Drivers in the survey data collected for AT& T (Lissy, 2000) reported that they did not think that their driving was impaired by cell phone usage and that the benefits outweighed any risk. Similarly, many of the participants in both of the experimental studies reported here thought that their driving was unimpaired. This was particularly true of the people who normally use a cell phone. Nevertheless, their driving ability on all measures clearly indicates that their driving and cognitive abilities were impaired significantly. The findings of the current investigation clearly

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reveal that drivers’ opinions of their own accuracy and safety when driving is not reliable and cannot be trusted. Survey research, such as that reported by Lissy (2000), and anecdotal reports cannot be relied upon to give an accurate measure of the effect of car phone usage while driving.

            Previous research (LaBerge, 1975; Posner, 1974) has revealed that processing of certain cognitive tasks can eventually, with practice, become almost automatic, thereby requiring little of our available processing capacity. Such tasks (for example, typewriting, playing a musical instrument, mastering emergency behaviors, etc.) at first take much of our attention to perform the task, but with practice, can became almost automatic. This then makes it possible for us to do something else at the same time. Apparently, safe driving and car phone usage continue to require active cognitive processing and cannot be automated like other cognitive tasks.

            Previous research has also shown that it is difficult to perform two tasks at the same time in the same modality, such as visual (Neisser, 1975) or auditory (Cherry, 1953). However, little research has focused on both visual and auditory tasks at the same time. The current research had participants drive and try to remember at the same time or separately. Drivers were unable to focus on the road and remember information simultaneously--both tasks were too difficult to do well.

            Manufacturers of car phones have recently argued that their hands-free car phones are much safer than the hand held phones. The current investigation clearly shows that this is not the case. For all of the variables measured, the hands-free phone showed no superiority over the hand held phone. This information needs to be provided to drivers as soon as possible.

            It was interesting that people who use car phones regularly thought that they were able to drive just as well, if not better, while on the car phone as while not on the car phone. However, their scores reflected just the opposite--their performance, along with everyone else’s, was significantly impaired while on the phone. These people reported that talking on the car phone helped them concentrate better and stay more focused. They were completely unaware of their errors. This finding is especially important because not only is driving impaired and concentration affected, but the drivers are unaware of these impairments.

            These findings are consistent with research recently reported in Science (de Fockert, Rees, Frith, and Lavie, 2001), which indicates that when participants are focusing attention on a foveal task, more errors are made in the ability to disregard irrelevant cues in the periphery. Because drivers do not recognize their lack of driving effectiveness, car phone use while driving seems especially dangerous. In answer to the experimental question of whether or not drivers can safely drive and simultaneously use a car phone, the results clearly indicate that caution should be used.

 

 

 

 

                                                                             


References

            Bad driving under the cellular phone influence. [On-line]. Available: http://www.btimes.co.za/97/0413/survey6.htm.

            Burton, L. (1986). Relationship between skills and learning style in problem solving Perceptual and Motor Skills, 62, 48-49.

            Cherry, C. (1953). Some experiments on the recognition of speech with one and with two ears. Journal of the Acoustic Society of America, 25, 975-979.

            de Fockert, J. W., Rees, G., Frith, C. D., & Lavie, N. (Mar 2, 2001). The Role of Working Memory in Visual Selective Attention. Science, 291, (5509), 1803-1806.

            Dotinga, R. (2000). Keep On Truckin’: Cell-phone car accident risk might be low. HealthScout, 1-4.

            Dotinga, R. (2000). “Hazard of car phones overstated” Dallas Morning News, Lissy, K. director Motor Vehicle and Public Health, Harvard Center of Risk Analysis.

            Ebersole, R. (2000, November 17). “Cell phone hang-ups: are cellular phone bad for your health?” Current Science, Weekly Reader, 86, 6, 4-7.

            LaBerge, D. (1975). Acquisition of automatic processing in perceptual and associative learning. In P. M. A. Rabbit and S. Dornic (Eds.), Attention and Performance V. London: Academic Press.

            Lissy, K. S. (2000). Cellular phones and driving: Weighing the risks and benefits. Harvard Center for Risk Analysis, 8.

            Miller, G.A. (1956). Magical number seven, + two: some limits on our capacity for processing information. Psychological Review, 63, 81-97

            Moray, N. (1959). Attention in dichotic listening: affective cues and the influence of instructions. Quarterly Journal of Experimental Psychology, 11, 56-60.

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            National Highway Traffic Safety Administration (NHTSA). (1997). An investigation of the safety implications of wireless communications in vehicles. [online]. Available: http://www.nhtsa.dot.gov./people/injury/research/wireless/ (October 25th, 1999).

            Neisser, U. & Becklen, R. (1975). Selective looking: attending to visually significant events. Cognitive Psychology, 7, 480-494.

            Posner, M. I., and Snyder, C. R. R., (1974). Attention and cognitive control. In R. L. Solso, (Ed.), Information Processing and Cognition: The Loyola Symposium. Hilldale New Jersey: Erlbaum.

            Phone may be factor in fatal crash. (2000, July 15). Dallas Morning News, p.7.

            Redelmeier, Donald A., and Tibshirani, Robert J. (1997). Association between cellular telephone calls and motor vehicle collisions. New England Journal of Medicine, 336, (7), 453-458.

Ridley, K. (1998). British scientists demand warnings for cellular phones. [On-line]. Available: http://www.nando.net.    

            Solso, R. L. (1998). Cognitive Psychology, fifth edition. Boston: Allyn and Bacon, pp. 129-153.

            Sternberg, R. S. (1996). Cognitive Psychology. Chicago: Houghton-Mifflin, pp. 100-120.

            Tulving, E. (1989a). Remembering and Knowing the Past. American Scientist, 77, pp.361-367.                                                                                   

            Wickens, D. D. (1970). Encoding categories of words: An empirical approach to meaning. Psychological Review, 77, 425-538.

            Wickens, D. D., Born, D. G., & Allen, C. K. (1963). Proactive inhibition and item similarity in short-term memory.  Journal of Verbal Learning and Verbal Behavior, 2, 440-445.


Table 1

Summary Table of Statistical Results for Experiment 1: Simulation Study

Means w/out Car Phone         Means with Car Phone             t-test (df) **             p value               6.36 minutes/lap                  6.83 minutes/lap                     t (24) = 2.885 p< 0.0081 *

  5.02 groceries remembered      2.58 groceries remembered   t (24) = 8.276                p< 0.00001*

  5.19 directions remembered      2.74 directions remembered    t (24) = 7.966              p< 0.00001*

16.8 swerves out of lane           30.72 swerves out of lane         t (24) = 7.848              p< 0.00001*

 9.52 hit objects                        19.68 hit objects                        t (24) = 5.669 p< 0.00001*

 5.88 car wrecks                     18.68 car wrecks                     t (24) = 4.635            p< 0.0001 *     *Denotes Statistical Significance                                          ** t-test for related samples

 

 

Table 2

Summary Table of Statistical Results for Experiment 2: Driving Course

Means w/out Car Phone         Means with Car Phone             t-test (df) **             p value              5.50  groceries remembered       2.63 groceries remembered   t (19) = 9.04                  p< 0.00001*

 6.94  directions remembered      2.95 directions remembered    t (19) = 11.92              p< 0.00001*

54.03 serpentine errors         103.75 serpentine errors   t (19) = 4.82                p< 0.0001*

 3.12  minutes/lap                       3.51 minutes/lap                     t (19) = 6.44                p< 0.00001*

20.35 course errors                  31.0  course errors                  t (19) = 4.81               p< 0.0001*

22.63 parallel parking             40.35 parallel parking             t (19) = 2.36             p< 0.0292 *     *Denotes Statistical Significance                                          ** t-test for related samples


Table 3             Summary of Planned Comparisons for Experiment 3: Hands Free

Treatment                                Means                                  t-test (df) **               p value             Groceries Recalled  No Phone vs.                     5.55                 t (19) = 3.320 p< 0.0089 *

                                    Regular Phone  3.95

 

Groceries Recalled       No Phone vs.               5.55                 t (19) = 5.676 p< 0.0003 *

                                    Hands Free Phone        2.80    

 

Groceries Recalled       Regular Phone vs.         3.95                 t (19) = 2.299 p< 0.06

                                    Hands Free Phone        2.80    

 

Directions Recalled       No Phone vs.               5.30                 t (19) = 4.385 p< 0.0018 *

                                    Regular Phone  3.40

 

Directions Recalled       No Phone vs.               5.30                 t (19) = 4.202 p< 0.0023 *

                                    Hands Free Phone        3.40    

 

Directions Recalled       Regular Phone vs.         3.40                 t (19) = 0.000 p< 0.9999

                                    Hands Free Phone        3.40    

 

Serpentine Task            No Phone vs.               25.30               t (19) =-2.478 p< 0.0351 *

                                    Regular Phone  45.40

 

Serpentine Task            No Phone vs.               25.30               t (19) = -2.858 p< 0.0188 *

                                    Hands Free Phone        59.00  

 

Serpentine Task            Regular Phone vs.         45.40               t (19) = -1.680             p< 0.1273

                                    Hands Free Phone        59.00  

 

Driving Course No Phone vs.               185.7               t (19) =-4.443 p< 0.0016 *

                                    Regular Phone  234.7

 

Driving Course No Phone vs.               185.7               t (19) =-3.863 p< 0.0038 *

                                    Hands Free Phone        229.0  

 

Driving Course Regular Phone vs.         234.7               t (19) = 0.661 p< 0.5253

                                    Hands Free Phone        229.0  

 

Parallel Parking No Phone vs.               24.6                 t (19) = -1693 p< 0.1247

                                    Regular Phone  41.9

 

Parallel Parking No Phone vs.               24.6                 t (19) =-4.009 p< 0.0031 *

                                    Hands Free Phone        45.2    

 

Parallel Parking Regular Phone vs.         41.9                 t (19) =-0.420 p< 0.6842

                                  Hands Free Phone       45.2                                                                         

*Denotes Statistical Significance                                    **Bonferonni t-test, for related samples


 

Figure Captions

Fig. 1 Driving Simulation - Cognitive Performance

Fig. 2 Driving Simulation - Driving Performance

Fig. 3 Driving Course - Cognitive Performance

Fig. 4 Driving Course - Driving Performance

Fig. 5 Hands Free Experiment - Cognitive Performance

Fig. 6 Hands Free Experiment- Driving Performance


 











Appendix B

Experimental Protocol

            The order of conditions for the participants was counterbalanced: for half of the participants their first time through the protocol was without the car phone and the second time through was with the car phone; for the other half of the participants they did the first course with the phone on and the second one with the phone off.

 

1.         Give grocery list for participant to memorize

2.         Give directions for participant to memorize

3.         Explain the Three Tasks: Serpentine, Driving Course, and Parallel Parking

4.         Recall groceries and directions

5.         Serpentine forwards and backwards

6.         Driving course

7.         Parallel Park

1.         Repeat procedure with the car phone on: Serpentine

2.         Driving Course

3.         Parallel Park

4.         Recall Groceries and Directions

 



 

Participant Code Number ________________

Experimenter: Hi! I need you to stop on the way home and pick up a few groceries from the store. Could you do that?

 

Experimenter: Okay, I am going to say some things that you need to get at the store, so you need to remember these items. So I know that you heard me clearly , I want you to repeat each item after I say it. Okay?

 

Experimenter: Okay. Repeat after me. We need:

            1 gallon of milk

            One bunch of green grapes

            24 pack of Coke

            A spray bottle of Windex

            A jar of spaghetti sauce

            A quart of Apple Juice

            2 Ripe tomatoes

            One pound of hamburger meat

 

Experimenter: Oh yeah. I also need you to go pick up my sone Billy from his friend’s house. Because you do not know how to get there I’ll give you directions. Okay? Could you repeat each part of the directions after me?

            You get on Lake Hefner Parkway going north and exit on Britton

            Turn right (or east) onto Britton and drive to May Ave.

            Then you make a left (or north) on May.

            Then you go for .2 miles to Quail Creek Road.

            Then you turn left on Quail Creek Road

            His house is the third on the left, and the address is 237 Quail Creek Road

 

Experimenter: Hi! I need you to stop on the way home and pick up a few groceries from the store. Could you do that?

 

Experimenter: Okay. I am going to say some things that you need to get at the store, so you need to remember these items. So I know that you heard me clearly, I want you to repeat each item after I say it. Okay?

 

Experimenter: Okay. Repeat after me. We need:

            1 quart of eggnog

            One bunch of ripe bananas

            12 pack of Dr. Pepper

            A spray bottle of 409 cleaner

            A can of chili with beans

            A quart of orange juice

            4 sweet potatoes

            One pound of bacon. Okay?

Experimenter:

class=Section14>

Oh yeah. I also need you to go pick up my daughter Jill from her friend’s house. Because you do not know how to get there I’ll give you directions. Okay? Could you repeat each part of the directions after me?

            You get on Lake Hefner Parkway going south and exit on 50th Street

            Turn left (or east) onto 50th St. and drive to May Ave.

            Then you make a right (or south) on May

            Then you go for .3 miles to Country Club Road

            Then you turn left on Country Club Road

            Her house is the second one on the right, and the address is 2605 Country Club Road

 

Car Phone Dialog:

What is your name? What is your date of birth? Where were you born? Where have you lived? Where were your parents born? How old are they? Where all have they lived?

 

How many brothers and sisters do you have? How old are they? Where all have they lived?

 

Where did you go to high school? When did you graduate?

 

When did you start college? How many hours have you completed? What is your classification?

 

What is your major? What do you plan to do when you graduate?

 

What classes are you taking next semester? What are the days and times of your classes?

 

What classes did you take last semester? What were the days and times? Who were your teachers? What grades did you make?


 

 

class=Section15>

Table 3                                                            Appendix C--Data Summary Sheet for Simulation Study

 

Participant Number

 

Time

off phone

 

Time

on phone

 

Groceries off phone

 

Groceries on phone

 

Directions off phone

 

Directions on phone

 

Lane swerves off phone

 

Lane swerves

on phone

 

Wrecks off phone

 

Wrecks on phone

 

Hits

off phone

 

Hits

on phone

 

1-F

 

7:24

 

8:40

 

4

 

2

 

7

 

4

 

21

 

31

 

6

 

11

 

2

 

9

 

2 -F

 

7:03

 

7:32

 

4

 

3

 

4

 

.5

 

15

 

34

 

5

 

6

 

6

 

9

 

3 -F

 

6:52

 

8:24

 

6.5

 

3.5

 

6.5

 

3

 

11

 

22

 

10

 

4

 

5

 

6

 

4-F

 

8:08

 

7:01

 

6.5

 

5

 

8

 

5

 

15

 

40

 

13

 

15

 

11

 

22

 

5 -F

 

7:13.40

 

8:26.06

 

6

 

2.5

 

5

 

4

 

16

 

21

 

3

 

13

 

8

 

14

 

6 -F

 

8:49

 

8:03

 

5

 

4

 

6

 

5

 

19

 

22

 

8

 

11

 

8

 

7

 

7 -F

 

7:49

 

7:56

 

6

 

2

 

3

 

3

 

8

 

26

 

3

 

2

 

1

 

6

 

8 -M

 

5:47

 

5:27

 

7

 

5

 

5

 

4

 

10

 

20

 

6

 

10

 

4

 

17

 

9 -F

 

5:40

 

6:01

 

2

 

1

 

 5

 

3

 

22

 

18

 

1

 

1

 

6

 

7

 

10-M

 

5:36

 

5:27

 

3

 

1

 

5

 

0

 

10

 

26

 

3

 

16

 

6

 

11

 

11-F

 

6:56

 

8:05

 

6

 

1.5

 

3.5

 

0

 

14

 

36

 

6

 

24

 

7

 

13

 

12-F

 

7:46

 

10:26

 

5.5

 

3.5

 

3

 

1

 

24

 

41

 

4

 

51

 

1

 

27

 

13-M

 

6:24

 

6:24

 

6

 

6

 

5

 

5

 

18

 

33

 

6

 

36

 

7

 

8

 

14-M

 

5:37

 

5:36

 

5

 

2

 

5

 

3

 

7

 

33

 

11

 

33

 

22

 

32

 

15-F

 

7:33

 

7:36

 

6.5

 

4

 

4.5

 

4.5

 

17

 

22

 

3

 

23

 

16

 

22

 

16-M

 

6:17

 

6:23

 

6

 

2

 

6

 

2

 

22

 

51

 

9

 

11

 

3

 

16

 

17-F

 

6:29

 

6:51

 

3

 

3.5

 

6

 

5

 

19

 

22

 

4

 

16

 

15

 

23

 

18-F

 

8:41

 

8:53

 

6

 

0

 

6

 

1

 

15

 

32

 

5

 

41

 

5

 

30

 

19-M

 

5.26

 

6.2

 

5

 

3

 

4

 

2

 

17

 

26

 

1

 

3

 

9

 

16

 

20-F

 

5.41

 

5.48

 

5

 

1.5

 

4.75

 

2

 

24

 

41

 

2

 

32

 

9

 

44

 

21-M

 

4.3

 

5.1

 

4

 

1.5

 

7

 

3

 

21

 

36

 

16

 

34

 

19

 

33

 

22-M

 

6.05

 

6.09

 

5.5

 

3

 

5.5

 

4

 

12

 

26

 

3

 

18

 

15

 

27

 

23-M

 

5.06

 

6.34

 

6.0

 

2

 

7

 

2.5

 

27

 

59

 

4

 

36

 

18

 

43

 

24-F

 

6.43

 

6.55

 

4

 

1

 

6

 

2

 

10

 

20

 

3

 

0

 

13

 

23

 

25-M

 

4.51

 

5.02

 

2

 

1

 

2

 

0

 

26

 

29

 

12

 

20

 

22

 

class=Section16>

 

 

 

 

 

 

 

 

 

 

 

 

 

27


Table 3                                                            Appendix C-Data Summary Sheet for Driving Study

Subj #

Age - Yrs Driving

Use car phone

Groceries off phone

Groceries on phone

Directions off phone

Directions on phone

Serpentine:  off phone

Serpentine: on phone

Time:   off phone

Time:     on phone

Tumblers + Counters: off phone

Tumblers + Counters:

on phone

Parallel Parking: off phone

Parallel Parking: on phone

1-F

28-13

NO

5

3

8

4

40

79

3.08

4.14

14

21

10

50

2 -F

23-7

NO

6

1

6

1

65

100

2.24

2.42

9

17

14

36

3 -F

35-19

YES

4

3.5

10

5

84

110

3.36

4.00

7

14

0

21

4-M

17-2

NO

4

1

4

1

102

148

3.11

3.42

30

45

20

26

5 -F

16-.2

NO

4

2

5

1

191

223

3.44

4.02

4

6

30

70

6 -M

46-30

YES

7

4.5

9

5

16

53

2.20

2.24

20

19

10

30

7 -M

24-8

NO

4

2

6

1.5

78

106

2.42

2.58

26

40

5

26

8 -M

22-6.5

YES

5

2

6

4.5

53

90

3.02

3.08

23

48

11

33

9 -M

26-10

NO

4

2

6.5

3

46

60

3.15

3.57

29

30

19

26

10-M

21-5

YES

5

.5

4.5

1

49

68

3.14

3.45

63

65

27

44

11-F

27-11

YES

7

4.5

7

0

33

165

2.53

3.09

26

43

40

117

12-M

25-7

NO

6

3

7

3

59

65

3.17

3.51

29

30

26

27

13-M

32-15

NO

7

3

12

6

95.5

452

3.54

3.58

27

47

9.5

54

14-F

33-20

YES

5

5

7

3

22.5

65

4.45

5.06

19

17

10

20

15-M

24-8

NO

7

3

11

5

55.5

114

3.55

4.07

27

37

25

60

16-F

45-29

YES

7

4.5

9

5

16

53

2.20

2.24

20

19

10

30

17-F

34-18

NO

7

3.5

6

5

19

25

3.20

3.55

4

16

15

23

18-F

26-9

NO

6

0

6

1

15

32

4.15

4.55

15

41

25

50

19-M

34-18

YES

5

3

4

2

17

26

3.13

3.55

13

33

10

20

20-F

25-8

NO

5

1.5

4.75

2

24

41

3.24

4.05

2

32

10

44

 

class=Section18>

Appendix E

EXPLANATION OF DATA CODES FROM DATA SUMMARY SHEET:

PARTICIPANT NUMBER- F or M= which participant followed by Gender, F= female; M= Male

AGE-Yrs. Driving= Age of participant following by the number of years they have driven

USE Car phone?= Yes or No about regular car phone use

GROCERIES-OFF = Number of grocery items remembered w/out phone on

GROCERIES-ON = Number of grocery items remembered with the phone on

DIRECTIONS-OFF = Number of direction points remembered w/out the phone on

DIRECTIONS-ON = Number of direction points remembered with phone on

SERPENTINE-OFF= Number of cones hit plus the distance from the end cone of 3 around which the drivers had to manipulate the car. Drivers drove forward and back and the distance was measured each time w/out phone on

SERPENTINE-ON = Number of cones hit plus the distance from the end cone around which the drivers had to manipulate the car. Drivers drove forward and back. The distance was measured with phone on.

TIME-OFF= Driving time around a driving course w/out talking on phone           

TIME-ON= Driving time around a driving course while talking on the phone

TUMBLERS + COUNTERS -OFF= Total number of tumblers felled plus increase in numbers on driving counter plus number of times the curb was hit during figure 8 without phone on

TUMBLERS + COUNTERS -ON = Total number of tumblers felled plus increase in numbers on a driving counter plus number of times the curb was hit during figure 8 with the phone on

PARALLEL PARKING-OFF = Total number of cones hit, times hit the curb, inches from the curb, and whether the driver signaled when parallel parking without the car phone on

PARALLEL PARKING-ON = Total number of cones hit, times hit the curb, inches from the curb, and whether the driver signaled when parallel parking with the car phone on

class=Section20>

 

Effect of Car Phone Usage on Cognitive Ability and Driving Performance

Table of Contents

Abstract

Introduction                                                                                                                                1

Experiment 1- Computer Driving Simulation                                                                                4

            Method                                                                                                                          4

           

            Results                                                                                                               5

 

                        Table 1                                                                                                   5

 

                        Figure 1                                                                                                              6

 

                        Figure 2                                                                                                              7

 

Experiment 2- Driving Course                                                                                         7

 

            Method                                                                                                                          8

 

            Results                                                                                                             10

 

                        Figure 3, Figure 4                                                                                             11

 

Experiment 3 - Hands-free Car Phone                                                                          12

 

                        Figure 5, Figure 6                                                                                             15

 

Conclusions                                                                                                                              16

 

Appendices

            A         Experimental Protocol                                                                           19

 

            B          Data Summary Sheet for Simulation Study                                                         23

 

            C         Data Summary Sheet for Driving Study                                                 24

 

            D         Explanation of Data Codes from Data Summary Sheet                          25

 

Bibliography                                                                                                                             26


Summary

            Many drivers talk on their cellular phones, or car phones, while driving. Currently, there exists a controversy about whether car phone usage should be allowed while driving. Two studies were conducted to determine the driving speed, accuracy, safety, and cognition while driving with and without using a car phone. Results revealed statistically significant differences with p < .0001, indicating car phone use adversely affected driving ability and memory of participants when using a car phone.

 

 

class=Section22>

            Currently, many drivers talk on car phones while driving.  controversy about whether car phone usage should be allowed while driving is sharp: some contend it is a personal freedom; others claim it is dangerous and should be legislated. The dangers of car phone use may include reduced competence and difficulty in concentration. Prior research indicates that people have difficulty processing information from more than one source simultaneously.  However, there is little scientific research on car phone usage. Therefore, it is important to determine, experimentally, whether car phone usage hurts ability to drive safely. The following research question was developed: Can drivers successfully do two things at the same time–drive safely and simultaneously use a car phone? Two studies were conducted to determine the driving speed, accuracy, safety, and cognition while driving with and without using a car phone. In the first investigation, 45 participants used a driving simulation. In the second investigation, 20 drivers were tested using three driving tasks: serpentine forward and backwards around cones; parallel parking; and driving a course which included other cars, a figure eight, and a railroad track. Experiment 3 included a hands free as well as a regular car phone. Drivers in all three studies completed the course: once while using a regular car phone, once without, and once with the hands free phone in the third study. The order of conditions was counterbalanced. Three equivalent lists of groceries and directions were used to test cognitive capabilities. The drivers’ speed and accuracy were recorded using several measures. A t-test or analysis of variance for repeated measures was performed on all five measures. Results revealed statistically significant differences with p < .0001, indicating car phone use adversely affected driving ability of participants with errors up150% when using a car phone. The ability to remember directions (6.9 vs. 2.9) and grocery items (5.5 vs. 2.6) accurately were also impaired significantly (with p < .0001) while talking on a car phone. Drivers were largely unaware of their impaired performance. The results clearly indicate car phone use is dangerous and caution should be used. 

 

The issue remains, however, whether the government should prohibit car phone usage with legislation, or should people have the right to drive more dangerously if they so choose. In my opinion, the government should exercise its power over the will of individuals in this situation. If one’s behavior is dangerous only to oneself, maybe the government should not become involved. However, in this instance, others’ lives are put in jeopardy, in addition to the driver.