Parent and Teen Factors Associated with the Amount and Variety of Supervised Practice Driving

Abstract

Despite the fact that a minimum number of practice hours for novice drivers has been widely adopted in the U.S., Australia, NZ and in some European countries, surprisingly little is known about the amount or variety of driving during the learner stage. One factor may be due to the difficulty in obtaining objective measures of the amount and conditions during which practice driving takes place. The purpose of this study was to use objective measures of the amount and variety of practice driving occurring during the learner permit stage, and examine how these differ according to individual and household level characteristics, which were measured at baseline using parent and teen surveys. We found that increased practice was associated with parenting practices, such as parent trust, as well as household income and pre-permit driving experience. Taken collectively, the findings suggest the amount of practice driving may be a function of the motivation or interest of the teen to drive, combined with the quality of the relationship between parents and teens and the household environment within which these characteristics are occurring. Surprisingly, in this study, teens from households with lower incomes gained more practice hours and days. Population level studies examining the association between the family context and how teenagers learn to drive are needed to confirm the findings from this study in a representative sample. The use of both naturalistic and survey methods used in this study demonstrates how they can build on one another.

1. Introduction

Despite the fact that a minimum number of practice hours for novice teenage drivers has been widely adopted in the United States as part of Graduated Drivers Licensing, surprisingly little is known about the amount or variety of driving during the learner stage. An improved understanding about why some teens practice more or experience more challenging driving environments may inform our understanding of how to improve practice driving and reduce the increase in crash risk during the transition to independent driving.

The literature on parent and teen engagement during the supervised driving period has identified some factors related to the experience of practice driving such as social support (Mirman et al., 2014), parental modelling of driving behavior (Taubman–Ben-Ari, 2010), and the pre-existing parent-teen dynamic (Laird, 2014). However, few studies have examined the relationships between these factors and the amount and variety of practice driving.

Currently, how often practice occurs during the day versus night or how often it provides exposure to a variety of driving conditions is unknown. In a rare, naturalistic driving study, the authors found practice driving was characterized mainly by routine driving trips on familiar roads, occurring in minimally challenging environments (Goodwin et al., 2010). Supervisors appeared to be focused on keeping their teens safe while they accumulated minimally challenging experiences. However, they did not measure the objective amount of driving that occurred during the learner period or the proportion of time that practice driving occurred at night or in wet weather.

In previous research, we examined the amount and nature of parent instruction during the learner permit period (Ehsani et al., 2017). We found that most driving instruction occurred in reaction to specific driving situations such as navigating and identifying hazards, which could be characterized as co-driving (Ehsani et al., 2017). We also examined factors related to how long learners remained on their permit and found that the number of months teens held their permit was not significantly associated with the amount of practice driving (hours or miles) they accumulated (Ehsani et al., 2016). The purpose of the current research was to build on these studies by describing the amount and variety of practice driving occurring during the learner permit stage and to examine how these vary according to individual and household level characteristics.

2. Materials and Methods

The primary vehicles of learner teenage drivers in southwestern Virginia, USA were instrumented with data acquisition capabilities within three weeks of obtaining a learner’s permit. These data acquisition systems were used for the purpose of measuring the amount of practice completed before progressing to independent licensure. Participants were instructed to drive as they would normally.

2.1. Consent and compensation:

Three consent forms were required for the study: parental consent and teenagers’ assent for learner participation, and an adult consent form for parent participation. Teenager assent was obtained separately from the parent to ensure their participation was voluntary and free of parental coercion. Teenage participants received $800 for completing the study, paid to them in installments as they completed key milestones. The protocol was approved by the Virginia Tech Institutional Review Board for the Protection of Human Subjects.

2.2. Vehicle Instrumentation:

Instrumentation was installed in the vehicle in which most practice driving would occur. The data acquisition system included a computer that received and stored continuous data from accelerometers, a global positioning system (GPS) that calculated vehicle position, and cameras. Video images monitored the driver’s face, the dashboard, and areas reachable by the driver’s hands, as well as the forward and rearward roadway. A microphone recorded in-vehicle conversation and driving instruction. Participants were followed for the duration of their learner permit period for a maximum of 24 months.

2.3. Trip coding:

Data coding was conducted on each trip file, including video and audio data generated during practice driving. A trip was defined as beginning when the vehicle ignition was turned on and ending when the ignition was turned off. Trip duration was calculated using the timestamp corresponding to ignition on and ignition off, regardless of vehicle movement. GPS recorded the movement of the vehicle and the distance traveled (miles) in each trip.

2.4. Outcome Measures:

We used four different measures to assess the amount and variety of practice driving.

2.4.1. Total practice driving hours:

Total driving hours were determined by using the sum of all trips during the learner stage.

2.4.2. Night driving hours:

Night driving was calculated using trip start times and merged with sunrise and sunset times for the day the trip occurred (Time and Date, 2015). If a trip began after sunset, it was considered as driving at night. In order to account for the variation in the amount of practice driving within the sample, the proportion of practice driving that occurred at night in relation to the total amount of driving during the learner period was also calculated.

2.4.3. Wet weather hours:

Wet weather driving was calculated using trip start times and merged with precipitation data for the region where the study was conducted (NOAA, 2015). If a trip began when there was precipitation, road conditions were coded as being wet. Here again, in order to account for the variation in the amount of practice driving within the sample, the proportion of practice driving that occurred in wet weather was calculated in relation to the total amount of driving during the learner period.

2.4.4. Days of practice driving:

The number of unique days when practice driving occurred during the learner permit stage was computed using the trip recorders. This measure is intended to measure the consistency of practice over the duration of the learner period. If multiple trips occurred on a single day, it was treated as a single trip occurring that day.

2.5. Predictors and Correlates of Practice Driving:

A number of survey instruments were administered at baseline to both parents and teens to measure individual characteristics and behaviors. These included demographic and household characteristics such as age of the participants, gender, and household income. The same scales were administered to parents and teens, with wording to make them teen- or parent-specific. In addition, the amount and nature of driving instruction provided by parents was assessed over the course of the practice driving period.

2.5.1. Teenagers’ pre-permit driving experience

was measured by eight items asking about the first time teens had driven or maneuvered different vehicle types and the number of times they had driven maneuvered each type. Vehicle types included cars/trucks, all-terrain vehicles, motorcycles/scooters, boats, jet skis, golf carts, tractors and lawn mowers. The frequency of driving/steering each vehicle type ranged from never to 5 or more times. The cumulative driving experience was summed across all vehicle types with never counted as zero and 5 or more times counted as five. The minimum possible score was zero while the maximum possible score was forty.

2.5.2. Trust of Teens

was measured by separately asking teens and parents how much parents trusted the teen. Six items were adapted from Simons-Morton et al. (2013) and ranged from general concepts -- “How much do you trust that your teen will not hang out with bad people?” -- to specific situations -- “How much do you trust that what your teen says s/he is going to do on a Saturday night is true?”. Responses ranged from 1 = Not at all to 4 = A lot. Questions administered to teens were worded identically but with the subject of the questions focusing on their perceptions of their parent. The responses were summed such that the minimum possible score was six whereas 24 was the maximum possible score.

2.5.3. Knowledge of Teen Activities

was measured by eight items separately asking teens and parents how much parents knew about their teens’ activities (Simons-Morton et al., 2013). For different behaviors, parents were asked “How often do you know…” with response options ranging from 1 = Never to 5 = Always. Examples of item questions include: “…what your teen is doing during his/her free time?” and “…where he/she goes when out with friends at night?”. Questions administered to teens were worded identically but with the subject of the questions focusing on their perceptions of their parent. The responses were summed such that the minimum possible score was eight while 40 was the maximum possible score.

2.5.4. Driving Instruction:

In addition to the survey scales administered at baseline, we measured the amount and nature of driving instruction that was provided by parents to teens during the practice driving period using video and audio data that were continuously recorded throughout the entire learner period. To assess the progression of practice over time, we sampled the data during the first and last ten hours of practice. The sampling protocol has been described in previously published studies (Ehsani et al., 2017; Ehsani et al., 2016). For each recorded segment, the conversation between parents and teens was coded as (1) related to driving; (2) not related to driving; (3) related to both driving and non-driving; or (4) no conversation present. In these analyses, we considered the total amount of instruction provided by parents.

2.5.5. Licensure timing

of participants was determined by requesting a copy of the participants’ driver’s license when they notified the research team they had progressed to their independent driving license. The duration of the learner permit period was calculated by subtracting the date of independent licensure from the date the learner permit was issued.

2.6. Analyses

Spearman rank correlations were calculated for the predictors and measures of the amount of practice driving. In previous analyses, we found that the length of the learner period was not significantly associated with the amount of practice that teens accumulated (Ehsani et al., 2016). Therefore, it was not included as a covariate. Multivariate linear regression was conducted to examine the association of the individual and household characteristics and the outcomes, adjusting for teen age, teen gender, and household income reported by parents. Statistical analyses were performed using SAS version 9.4.

3. Results

Demographic characteristics of the sample (n = 90) are presented in Table 1. On average, teens were 15.61 years old (SD = 0.16) and the sample was 54.4% female. Approximately half the parents (47.8%) reported a household income of at least $100,000 annually. In Virginia, USA, where the study was conducted, novice teenage drivers are required to hold the learner’s permit for at least nine months. Of the 90 novice teen drivers in the sample, 83 participants completed the learner permit stage and advanced to independent licensure. The average learner permit duration for these teens was 10.35 months (SD = 2.48).

Table 1:

Sample Characteristics

Measures	n	%
Gender
Female	49	54.44
Male	41	45.55
Race/Ethnicity
White	82	91.11
Black	3	3.33
Other	5	5.55
Age at instrumentation (in years)
15.5	43	47.78
15.6	21	23.33
15.7	8	8.89
15.8	8	8.89
15.9	4	4.44
16.0	4	4.44
16.1	2	2.20
Household Income
< $100,000 annually	47	52.22
≥ $100,000 annually	43	47.78

The psychometric properties of the survey measures and the distribution of the measures of practice driving are described in Table 2. During the learner permit period, teens drove for an average of 46.59 hours (SD = 32.83) in total, 10.07 hours (SD = 10.18) at night, and 5.15 hours (SD = 4.16) in wet weather. Close to one-fifth of practice occurred at night (19.7%, SD = 10.51) and 10.86% of practice (SD = 4.82) occurred in wet weather. The mean number of days teens drove during the practice period was 87.12 (SD = 44.77). On average, females practiced 50.26 hours (SD = 37.43) and males practiced 42.21 hours (SD = 26.09), though there were no significant differences by gender across the measures of the amount of practice driving. The number of hours practiced (including at night or in wet weather) and number of days teens drove were not significantly associated with the learner permit duration.

Table 2:

Descriptive statistics of total hours of practice driving, hours of nighttime practice driving, hours of wet weather practice driving, total days of practice driving, pre-permit driving experience, teen’s perception of parental trust, and parental knowledge (from the parent’s perspective).

Measure	n	Number of items	Mean	Min.	Max.	SD	Median	Internal Consistency#
Total Hours of Practice Driving	90	---	46.59	0.65	210.72	32.83	40.39	---
Hours of Nighttime Practice Driving	89	---	10.07	0.07	53.86	10.18	6.97	---
Hours of Wet Weather Practice Driving	89	---	5.15	0.03	24.63	4.16	4.10	---
Total Days of Practice Driving	90	---	87.12	4.00	203.00	44.77	84.50	---
Pre-permit Driving Experience	90	8	13.51	0.00	40.00	8.55	13.00	0.69
Teen’s Perception of Parental Trust	90	6	20.92	6.00	24.00	3.29	22.00	0.82
Parental Knowledge	90	8	34.19	26.00	40.00	3.07	34.00	0.79

^#Standardized Cronbach’s α

Table 3 shows Spearman rank correlations between survey variables and the outcomes of interest. Pre-permit experience, teen perception of parental trust, and parental knowledge (from the parents’ perspective) were correlated with at least one of the outcomes at the significance cutoff of p = 0.10. Greater pre-permit experience was correlated with more hours of practice (including at night and in wet weather). Teen perceptions of parental trust were positively correlated with all measures of practice amount and variety. Parental knowledge was also positively correlated with hours of nighttime driving, hours of wet weather driving, and days of driving. There was a significant negative association between the total amount of instruction provided by parents during practice and each measure of practice driving.

Table 3:

Baseline survey scales and correlation with amount and variety of practice driving (N=90).

Practice Driving Outcomes	Teen Measures			Parent Measures
	Amount of Pre-permit Experience	Teen’s Perception of Parental Trust	Teen’s Perception of Parental Knowledge	Parental Trust	Parental Knowledge	Total Driving Instruction^
Practice Driving Hours	0.22**	0.20*	n.s.	n.s.	n.s.	−0.36***
Night Hours	0.20*	0.25**	n.s.	n.s.	0.22**	−0.26**
Wet Weather Hours	0.26*	0.21**	n.s.	n.s.	0.18***	−0.32***
Days of Practice Driving	n.s.	0.23**	n.s.	n.s.	0.20*	−0.40***

^*p ≤ 0.10

^**p ≤ 0.05

^***p ≤ 0.01

^{^}All types of driving instruction provided by parents

Abbreviations: n.s. – non-significant

Multivariate linear regression using each set of significant predictors are presented in Table 4. Pre-permit experience (β = 0.88, p ≤ 0.05) was significantly positively associated with the total hours of practice driving and hours of wet weather driving (β = 0.12, p ≤ 0.05). Teen perception of parental trust had a marginal positive association with days of practice driving (β = 2.37, p ≤ 0.10). Teens from households with annual income of at least $100,000 drove fewer hours overall (β = −17.56; marginally significant at p ≤ 0.01) and at night (β = −4.22, p ≤ 0.05) and fewer in wet weather (β = −1.65, marginally significant at p ≤ 0.10) than those from a household with less than $100,000 in annual income. Finally, higher household income was significantly associated (β = −23.58, p ≤ 0.05) with fewer days of practice.

Table 4:

Multivariate model showing association between significant baseline characteristics with amount and variety of practice driving (N=90).

Practice Driving Outcomes	Pre-permit Experience#		Parental Knowledge^		Teen’s Perception of Parental Trust#		Teen Age		Teen Gender (Ref: Female)		HH Income (Ref: < $100,000)
	β	95% CI	β	95% CI	β	95% CI	β	95% CI	β	95% CI	β	95% CI
Practice Driving Hours	0.88**	(0.07, 1.69)	---°	---°	1.17	(−0.88, 3.21)	−22.39	(−64.59, 19.80)	−10.37	(−23.81, 3.07)	−17.56***	(−30.48, −4.63)
Night Hours	0.13	(−0.13, 0.38)	0.62	(−0.14, 1.37)	0.53	(−0.12, 1.19)	−6.22	(−19.71, 7.28)	1.05	(−3.39, 5.50)	−4.22**	(−8.40, −0.05)
Wet Weather Hours	0.12**	(0.01, 0.22)	0.11	(−0.20, 0.42)	0.17	(−0.10, 0.44)	−1.46	(−7.04, 4.13)	−0.68	(−2.51, 1.16)	−1.65*	(−3.38, 0.07)
Days of Practice Driving	---°	---°	1.14	(−2.17, 4.45)	2.43*	(−0.43, 5.29)	−41.44	(−99.49, 16.61)	−2.36	(−21.59, 16.87)	−23.48**	(−41.76, −5.20)

^*p ≤ 0.10

^**p ≤ 0.05

^***p ≤ 0.01

^°Multivariate models only included predictors correlated with outcomes at p ≤ .10 (see table 3). All models adjusted for teen age, teen gender, and household income.

^{^}Baseline measure administered to parents

^#Baseline measure administered to teens

Abbreviations: HH – household income

4. Discussion

The purpose of this study was to examine teen and parent factors associated with the amount and variety of practice driving that a sample of novice teenage drivers accumulated during the learner permit period. Across all measures of driving exposure, teens from households with incomes of less than $100,000 drove significantly more (or trended towards significance) than their peers from households with higher incomes.. This finding was unexpected, as higher household income is associated with an earlier age of licensure (Tefft et al., 2013; Tefft et al., 2014) and greater household resources that can be devoted to practice driving such as multiple household vehicles. Possibly, there was more urgency to practice and advance to licensure among lower income than higher income families. To our knowledge, this is the first time the inverse association between household income and practice driving has been described, although our sample was largely middle class and may not reflect the full range of economic diversity that exists in the general population. Another reason may be that the study population was a highly motivated sample of novice drivers and of parents who committed to ongoing assessment via surveys and naturalistic measurement of driving behavior, possibly indicating greater parental involvement and interest in the process of learning to drive than the average teen in Virginia.

A strong parent-teen relationship during the practice driving period would be expected to promote extensive practice (Mirman et al., 2014; Taubman–Ben-Ari, 2010; Laird, 2014). In this study, of the several measures of parenting practices assessed, we found that teens’ perceptions of parental trust was the one such variable marginally associated (p ≤ 0.10) with more days of driving. Research on learning has consistently established that distributed practice is more effective for long-term retention than massed practice (Kwon et al., 2015), suggesting that the goal of the learner period should not only be to practice extensively but also to spread out practice over a substantial timeline. This implies that interventions to improve the amount of practice may need to consider the relational aspects between parents and teens during the supervised practice driving period (Mirman et al., 2014).

The amount of pre-permit driving was significantly and positively associated with the total amount of practice driving and amount of driving at night. This might reflect an affinity towards vehicles and driving among teens and/or parents or some other unknown motivational, environmental, or parent-teen relational factors. As practice driving increased, the total amount of parental instruction decreased. This association was particularly pronounced for functional instruction during the final hours of practice, suggesting that parents may have been calibrating their instruction according to the skills and capabilities of the teen drivers, who were no longer needing guidance about specific events that were occurring.

4.1. Limitations

Any practice driving that occurred in non-instrumented vehicles was not included in our estimate of how much teens drove during the learner permit period. Therefore, it is possible that the measures of exposure are under-estimates of the amount of driving that took place. All study participants were required to complete the standard driver education course, which would have contributed to their learning and experience apart from parent-supervised practice. We did not measure when teenagers took the behind-the-wheel test and the number of test attempts, which may have had implications for learner permit duration and the hours of practice driving.

5. Conclusions

With more time and a broader range of experiences, learners are more likely to develop the skills to drive safely. The extended period of supervision also provides a greater opportunity for parents to establish expectations for safe independent driving (Simons-Morton and Ehsani, 2016). Our findings are consistent with the contention that increased practice driving is associated with parenting practices, such as parent trust, pre-permit driving experience, and with household income (albeit in the opposite direction). Taken collectively, the findings suggest the amount of practice driving may be a function of the motivation or interest of the teen to drive, possibly combined with the quality of the relationship between parents and teens and the household environment within which these characteristics are present. Surprisingly, in this study, teens from households with lower incomes gained more practice hours and days. These findings build on a body of literature that indicate parents and the family context are important sources of influence in the process of learning to drive. Population level studies examining the association between the family context and how teenagers learn to drive are needed to confirm the findings from this study in a representative sample.

Highlights:

• Practice driving amount and variety differed widely among participants in a naturalistic driving study

• Having driven before receiving a learner permit was associated with more driving overall, and driving in wet weather

• Factors related to parent-teen relationship (such as trust) were associated with more days of practice

• Higher household income was associated with less practice driving