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Research methods and models of driver behavior

studies

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Measures of crashes and injury rates

Number of injuries Not useful for making comparisons

Number of deaths Not useful for making comparisons

Fatalities per 10.000 vehicle A limitted measure because it omits non-motorized

transport Fatalities per 100.000 population Fatalities per vehicle-km traveled

Does not take into account non-motorized transport

Road traffic accident statistics from Turkey

In 2012, total of 1.296.636 car accidents happened in which 3750 people died and 268.102 people were injured in Turkey (EGM, 2013).

Road fatalities per 100.000 inhabitants per year was 12, and road fatalities per 100.000 motor vehicles was 97.1 in Turkey (Wikipedia, 2013)

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WHO, 2013

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Motorization and crash rates

Smeed’s law involvement of each vehicle in a fatal crash

decreases as the number of cars in a country increase. WHY?

factors which co-vary with the increasing (improvements in transportation infrastructure, higher urbanization etc.) motorization can explain this relationship

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Variables of interest in traffic safety research

Independent variable E.g., speed, alcohol intake

Dependent variable E.g., crash likelihood

Control variables Variables that can affect dependent variable

so their level should be constant E.g., education level, SES status

Variables of interest in traffic safety research

Confounding variables Variable that is not controlled or

manipulated but might affect the results E.g., exposure to traffic

Intervening variables Variable that intervenes between independent

and dependent variable E.g., phone use driving performance

accident

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Research methods in traffic pychology

Self-report methods Observational methods Labaratory research Instrumented vehicle studies Case-control studies

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Research methods in traffic pychology

Self-report method Includes questionnaires, inventories,interviews etc. Based on the self-reports of the subjects ADVANTAGES

easy to apply inexpensive provide more detailed information reach large number of people

DISADVANTAGES Forgetting past driving behavior Social desirability concerns..

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Research methods in traffic pychology

Observational studies Roaduser behavior is observed on the road Direct vs unobstrusive observation

Direct observation >researcher is visible to road users while making the observation

Unobstrusive observation> researcher is not visible to road users

Advantages Directt observation of the behaviors, no social

desirability bias Disadvantages

You can not observe every behavior, such as past accident involvement 10

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Research methods in traffic pychology

Laboratory research Digital simulation studies

Computer programs run a hypothetical situation

Advantage Experimenter has the complete control of the

situation Disadvantage

Generalizing the results from the lab to real world is limitted

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Research methods in traffic pychology

Driving simulator studies How valid are the

results of the driving simulator studies?

Research methods in traffic pychology

Instrumented vehicle studies

Detailed data related to road traffic safety can be collected

High validity!

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Research methods in traffic pychology

Case-control studies an epidemiological study design ‘ a sampling strategy in which the population

under study is selected based on the presense or absence of an event of interest (i.e., health, condition, disease, death) (Lazcano et al., 2001).

The aim is to identify causal factors of the events of interest by comparing characteristics of both groups (case and control group)

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Research methods

Validity of the studies Did the study actually measured the

thing it reportedly measure?

Are the findings stable and replicable in other studies?

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Research methods

Threats to the validity Biases in the reports of police accident

data Biases in self-reports Problems in stimulator studies

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Theories and models of driver behavior

Hierarchical decision making theories Based on the idea that driving requires hierarchical

decision making E.g., Janssen (1979) proposed a hierarchical system for

the driving decisions Strategic level

General planning (which route to choose, when to live etc.) Maneuvering level

Tactical/navigation level decisions (how to avoid obstacles, when to change lanes..)

Control level Mostly unconscious and include moment to moment actions

(accelerating, changing gears etc.)

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Theories and models of driver behavior

Attention and information processing models People have a limited attention capacity

Attention is allocated to multiple things when driving

Limited capacity human information processing model by Wickens (1992)

A limitted capacity model of driver information processing by Shinar (1978)

Limited capacity human information processing model by Wickens, 1992

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Theories and models of driver behavior

Rational decision making models Based on the idea that people are rational

decision makers but their rationality is biased in many ways

Sivak’s (2002) ‘bounded rationality’ application for driver behavior

people’s rationality is bounded or limitted in some situations so they modify their behaviors based on experience

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Theories and models of driver behavior

Rational decision making models Ajzen’s theory of planned behavior

Behavior is determined by intentions which are based on our attitudes, subjective norms, and perceived behavioral control

Attitudes – evaluation of the behavior Subjective norm – how the close other think about

engaging in a certain behavior Perceived behavioral control – perceived control

level on the behavior

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Theories and models of driver behavior

Theory of Planned Behavior (Ajzen, 1991)

Attitudes

Subjective Norm

Intention Behavior

PerceivedBehavioralComponent

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Theories and models of driver behavior

Motivational models Driver motivations are the key

determinants of the driving style and safety

We have different motivations for driving Mobility Minimizing risk

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Theories and models of driver behavior

Motivational models They emphasize the human motivation as the

key determinants of driving style and safety

E.g., Risk homeostasis theory (Wilde, 1998, 1992) People want to reduce risk to a non-zero level which

they can tolerate Target level of risk vs perceived level of risk

In order to improve safety in long run, target level of risk should be changed

Risk Homeostasis Theory, Wilde, 1998, 2002)

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Theories and models of driver behavior

Integrative models On-road behaviors are determined both by

motivational factors and information processing limits

Classification for aberrant behaviors by Reason et al. (1990) Driving violations

Deliberate actions that are considered to be unsafe. E.g., speeding, drinking and driving

Driving errors Failures of planned actions to achieve their intended

consequences. E.g., selecting a wrong lane, forgeting the place of your car in a car park