1 Research methods and models of driver behavior studies

2 Measures of crashes and injury rates Number of injuries Not useful for making comparisons Number of deaths Not useful for making comparisons Fatalities per vehicle A limitted measure because it omits non-motorized transport Fatalities per population Fatalities per vehicle-km traveled Does not take into account non-motorized transport

Road traffic accident statistics from Turkey In 2012, total of car accidents happened in which 3750 people died and people were injured in Turkey (EGM, 2013). Road fatalities per inhabitants per year was 12, and road fatalities per motor vehicles was 97.1 in Turkey (Wikipedia, 2013) 3

4 WHO, 2013

5 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

6 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 7

Research methods in traffic pychology Self-report methods Observational methods Labaratory research Instrumented vehicle studies Case-control studies 8

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.. 9

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

11 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

12 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! 13

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) 14

15 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?

16 Research methods Threats to the validity Biases in the reports of police accident data Biases in self-reports Problems in stimulator studies

17 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.)

18 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,

20 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

21 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

22 Theories and models of driver behavior Theory of Planned Behavior (Ajzen, 1991) Attitudes Subjective Norm Intention Behavior Perceived Behavioral Component

23 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

24 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) 25

26 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