Risk-adaptation theory

An introduction is given to our psychophysical response and valence theory of choice behaviour, since the risk-adaptation theory derives from that theory as an application. Risk-adaptation theory assumes that road users implicitly evaluate their risks by oppositely oriented, single-peaked valence functions of arousal and fear sensations as dependent aspects of risks in road traffic. Due to this dependence and the adaptation to changing risk levels, these single-peaked valence functions combine additively to a dynamic shifting interval of ambivalent risk indifference, where above and below the risk evaluation is increasingly negative. Risk-adaptation theory contains the zero-risk, threat-avoidance, and risk-homeostasis theories as special cases and predicts that: (1) fatality risks decay exponentially, (2) the slope parameter for the exponential fatality risk decay is 1½ larger than for the traffic growth function, (3) a safety measure with a very large effect will be initially compensated to a lesser low risk level than otherwise expected, and (4) the contributions of a road safety measure to danger perception and arousal level determines whether its expected safety effect will be reinforced or adversely compensated. Each prediction is tentatively verified by some research.