What drives the driver? Surface tensions and hidden consensus

Ray Fuller, School of Psychology, Trinity College Dublin

The Task-Capability Interface model, like several others such as Risk Homeostasis theory, Vaa’s ‘monitor model’ and Summala’s ‘comfort zone model’, is principally concerned with describing motivational influences on driver decision-making. The Task-Capability Interface model is predicated on the inescapable fact that collisions occur when, for a multitude of possible reasons, drivers allow task demand to approach and exceed their capability. It is the identification of these reasons which promises to throw light on how safety might be more reliably achieved as a concomitant outcome of our seemingly insatiable desire for greater mobility.

The aim of this chapter is to present recent developments in the Task-Capability Interface and other models and to explore key differences and similarities. The Task-Capability Interface model now more explicitly distinguishes between distal and proximal motivational determinants and takes account of factors influencing motivation to comply with traffic regulations and of factors which impact on the range of task difficulty that a driver seeks to experience (task-difficulty homeostasis). Evidence shows that temporary factors can powerfully influence this range of difficulty, hence the latest formulation of the model replaces the concept of homeostasis with that of allostasis. Allostasis is defined in this context as ‘maintaining a particular level of task difficulty or risk feeling that varies according to an individual’s needs and circumstances’. It is important to note in this conceptualization that the term risk feeling is not intended to imply any kind of statistical risk estimate and risk feeling does not relate to such a statistical risk estimate (as postulated in Risk Homeostasis theory, for example).

Along with recent developments in Vaa’s ‘monitor model’ and Summala’s ‘comfort zone model’, the Task Difficulty Allostasis concept raises intriguing questions concerning the role of feeling in driver decision-making, particularly in relation to emotional responses both to elements in the road and traffic scene and to deviations from internalized goal states of the driver.

The models reviewed here are fundamentally based on control theory concepts involving the driver comparing sensed information to some standard or standards, arising out of her or his motivation, and acting to keep any discrepancies within acceptable limits. Where they appear to differ is in terms of what those standard might be. However such differences may be more apparent than real and there is reason to believe that there is an emerging convergence in driver motivational theory. Many empirical questions remain, however. For example, how does a driver become aware of (or implicitly use feedback relating to) the standards she or he has set? Answers to such questions point to possible future directions for theory development and a new agenda for driver behaviour research.