What's Your Safety Personality?

TASA ID: 9075

Do you have a safety personality behind the wheel?  Yes!  Everyone has a safety personality.  That’s because everyone has a personality, and several universal personality dimensions affect safety behavior.  Driver personality is the strongest of various personal factors affecting safety outcomes, in my opinion.  Others include driver age, gender, sensory-motor performance (e.g., reaction time), medical conditions, and mental abilities.  All of these can affect driver crash risk, sometimes strongly.  Yet it is my conclusion that driver personality exerts the greatest enduring affects.

What is personality?  You might think of it as just behavior patterns in social situations.  We all know both extraverts and introverts, for example.  Yet it is more than that.  Personality is your long-term consistencies of behavior, compared to others.  This consistency is seen across decades of time and across a variety of situations.  Think about yourself and 3-4 other people whom you have known for a long time, and across different situations.  Who is the calmest person you know well?  The most aggressive?  The most friendly?

Maybe you are thinking that yes, people have individual differences in their behavior patterns, but that crash involvement is more a function of the environment and of just plain luck.  Those elements are strong also.  Traffic density is the biggest environmental factor affecting your safety on the roads each day.  And traffic crashes, especially serious ones, are rare events relative to all the hours and miles of driving.  Luck plays a role.  Even the worst drivers have to be unlucky to find themselves involved in a crash on any given day.

The vagaries of life notwithstanding, individual personality effects become evident over time. Studies of groups of drivers, such as those in a truck or other motor vehicle fleet, show repeatedly that there are wide variations in drivers’ rates of risky behaviors.  The same individuals tend to exhibit the highest risks over time.

One way to show this is to instrument fleet vehicles with sensors recording speeds, accelerations, decelerations (e.g., hard braking events), swerves, and close proximities to other vehicles.  Many large studies have captured and recorded these events, along with video footage of drivers’ actions and surrounding traffic.  Driver subjects are fully informed of the instrumentation and are compensated for agreeing to drive “in a fishbowl.”  Observations over their first weeks show clearly that drivers habituate quickly to the sensors and behave as usual, whether good or bad.  A few actual crashes are captured, but most of the events are “near-misses” or other aberrant incidents.  Capturing a lot of events means more reliable statistics.

A commercial fleet study rank-ordered 95 truck drivers by their rate of involvement in these kinds of at-fault events (described in Knipling, 2009).  If involvements were just a matter of chance, you’d expect all the drivers to average out about the same.  Yet the worst drivers, with just 19% of total mileage exposure, accounted for 53% of all the at-fault events.  The remaining drivers with 81% of exposure were involved in just 47% of the at-fault close calls.  Findings like this are seen reliably in instrumented fleet studies.  My conclusion is that, in almost any group of drivers, 15-20% of drivers account for 50% or more of total driver error and; therefore, liability risk.  By the way, the single very worst driver of the 95 did 0.9% of the total driving but had 6.3% of all at-fault events.  He was seven times riskier than the average subject in the study.

There’s a bright side to this coin.  The good drivers had 81% of the exposure but less than half (47%) of the total risk.  Event counts even showed that 18 of the 95 drivers never made a detectable mistake.  Fleet managers should pick out their bad apples but also recognize and appreciate all their good ones.

What if someone came back a year later and retested the same 95 drivers?  Would the good and bad ones still be the same?  The study did not do that, but evidence suggests that risk rankings wouldn’t change much.  I conducted a survey (Knipling et al., 2004) of 178 motor carrier safety directors and 67 other experts (i.e., researchers, consultants, administrators) which addressed the question of risk consistency over time.  When asked about the year-to-year consistency of driver risk, 67% of the safety directors said that relative driver risk stays about the same.  Only 10% believed that relative risk can change dramatically.  Among the other experts, 65% said that risk stays about the same.  None of the 67 believed that individual risk can change dramatically. 

So where do personality traits fit in this puzzle?  Personality traits are measured along dimensions, not classified in distinct categories like blood type.  Traits are scored by survey responses, answers to interview questions, and by behavioral observations.  Personality research is thus fuzzy compared to other safety science.  It is still compelling, though.

One personality trait with a strong relation to safety is sensation-seeking.  People scoring high on this measure tend to seek excitement, take risks, and get bored easily.  Sound like anyone you know?  Sensation-seeking usually peaks in late adolescence, but individual differences among people remain for decades.  Would you rather go to a party or read a book?  People who seek “action” at a party tend also to seek “action” while driving.

Impulsivity is another personal red flag.  It’s the inability to control impulses, which of course leads to hasty actions and errors.  Impulsivity is strongly related to driving mistakes and misbehaviors.  Driving presents an instantaneous personality test every time you approach a green-to-amber traffic signal change.  With exceptions, we can infer impulsivity and risk-taking tendencies when drivers run the red.

Aggressiveness and anger-proneness are overlapping personality traits.  Aggressive people are hard-charging, competitive, and impatient.  People who are easily provoked can become wrathful behind the wheel.  We’ve all had that road rage gut reaction, but some much more than others.  My survey of 178 fleet safety directors asked them to rate the relative risk associated with 16 personal factors.  “Aggressive/angry” was the #1 culprit, followed closely by “impatient/ impulsive.”  The traits judged least risky of those offered included “older driver” and “introverted/unsociable.”  

Decades of personality research has developed and elaborated the “Big Five” model of personality (Little, 2017).  The five dimensions don’t encompass everything about a person, but they tell you a lot.  The mnemonic “OCEAN” helps one to remember the five dimensions, listed below.  Research finds that two of the five dimensions correlate most highly with safe and unsafe tendencies.  As you read the list, try to pick out the two strongest safety indicators.  The “Big Five” personality dimensions are:

• Open to experience (vs. Closed)
• Conscientious (vs. Casual)
• Extraverted (vs. Introverted)
• Agreeable (vs. Disagreeable)
• Neurotic (vs. Stable).

What are your choices for the two that correlate most closely with behavioral safety?  If you were hiring fleet drivers (or employees for any job with risks), you should seek out these two traits.  A hint is that the same two personality traits correlate most highly with worker retention (Zimmerman, 2008; Knipling et al., 2011).  Driver retention is highly prized in commercial fleets because of the driver shortage.

The American Transportation Research Institute, or ATRI (Boris & Luciana, 2017), reviewed personality traits and other personal risk factors in relation to truck driving safety.  Their focus was on young truck drivers (18-25) but their results apply generally.  They prioritized two of the “Big Five” as desired truck driver traits.  Those two were Conscientiousness and Agreeableness.

The Conscientious personality embraces rule-following and traditional values.  At the other end of this dimension, the casual personality interprets rules loosely and might scorn conventional thinking.  Casual people aren’t necessarily bad.  Little (2017) cites a study finding that the best jazz musicians scored low on conscientiousness.  They could improvise because they weren’t shackled by rules.  In driving, however, ATRI reported that low conscientiousness was associated with carelessness.  You might have trouble getting safely across town if you improvise while driving.

Agreeableness is less obvious as a safety correlate.  ATRI’s study focused on drivers who would be hired to drive for a fleet and; therefore, follow its rules; i.e., be a reliable team member.  Agreeable personalities are motivated to get along smoothly with others and not “make waves.”  For them, rule-following is the way to sustain positive relationships.  The “go along to get along.”  At the other extreme, disagreeable people aren’t motivated to get along and may be argumentative about rules and expectations.

Most companies don’t use formal personality tests in their driver screening and hiring, but more should.  If you interview job candidates, just being aware of these personality dimensions might help you make better choices.  And remember that the whole concept of personality rests on the long-term consistency of behavior.  Past behavior predicts future behavior.  Past driving behavior is most relevant, but look for non-driving red flags as well.  A sad truth is that non-driving criminality is associated with elevated crash risks, twofold or more according to one leading expert (Evans, 2004).  

As one who has studied the safety management of fleets, I advocate using every trick in the book to field safe vehicles, drivers, and operations.  Do everything you can, across the board.  Yet some management areas are more important than others.  In a different survey, my colleagues and I (Knipling et al., 2011) asked fleet safety directors to choose the single most important area of fleet safety management from five choices.  The answer “All of the above” was not permitted.  The five management choices were:

1. Driver Orientation & Training
2. Driver Selection and Hiring
3. Company Communications
4. Driver Monitoring & Evaluation
5. Rewards & Discipline.

Notice that Choices 1, 3, and 5 above are all related to changing drivers to make them better.  In contrast, Choices 2 and 4 are about assessing drivers as they actually are.  How did safety directors allocate their 1^st place votes?  Choices 2 and 4 together received 60% of the votes, about 30% each.  The combined total of Choices 1, 3, and 5 was 40%, about 13% each.  Stated simply, the safety directors placed higher value on accurately assessing drivers’ safety than on trying to change it.

To say that one’s personality is “fixed” is too strong a statement.  Enduring yes, but not immutable.  Personality scientist Brian Little (2017) suggests that our personality roots arise deeply from our genetics and social histories, but that self-aware individuals can transcend their engrained tendencies.  An introverted person can learn to function well socially and even become an influential leader, if that’s a necessity or a strong aspiration.  Similarly, some drivers can transcend their past mistakes and commit to safe behaviors going forward.  Personality is from your core, but it doesn’t have to be your destiny.

Cited References

ATRI.  Research identifies multiple characteristics that may identify safe younger drivers.  Research summary available at truckingresearch.org. Undated, downloaded 2021.

ATRI (Boris, C. & Luciana, M.M.).  Developing a Younger Driver Assessment Tool Technical Memorandum #1.  2017.  Available at truckingresearch.org. 

Evans, L.  Traffic Safety.  Science Serving Society, Bloomfield Hills, MI. ISBN 0-9754871-0-8, 2004.

Knipling, R.R.  Safety for the Long Haul; Large Truck Crash Risk, Causation, & Prevention.  American Trucking Associations.  ISBN 978-0-692-00073-1, 2009.  Information available at www.safetyforthelonghaul.com.

Knipling, R.R., Boyle, L.N., Hickman, J.S., York, J.S., Daecher, C., Olsen, E. C. B., and Prailey, T.D.  Synthesis Report #4:   Individual Differences and the High- Risk Commercial Driver.  TRB Commercial Truck & Bus Synthesis Program.  ISSN 1544-6808, ISBN 0-309-08810-0, 2004a.

Knipling, R.R., Burks, S.V., Starner, K. M., Thorpe, C.P., Barnes, M. J. & Bergoffen, G.  Driver Selection Tests & Measurements.  CTBSSP Synthesis 21, TRB, ISBN 978-0-309-22339-9,  http://www.trb.org/Publications/PubsCTBSSPSynthesisReports.aspx, 2011.

Little, Brian R.  Who Are You, Really; The Surprising Puzzle of Personality.  TED Books/Simon & Schuster, ISBN 978-1-5011-1996-5, 2017.

Zimmerman, R.D.  Understanding the impact of personality traits on individuals’ turnover decisions: a meta-analytic path model.  Personnel Psychology, 61, 2008, Pp. 309-348.

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