System reliability and maps

Respondents were asked to rate the degree of correspondence between system-generated routing advice and their own individual preference when driving in familiar areas. It was hoped this item would be a useful measure of perceived system reliability/ efficiency, as most drivers are aware of optimal routes in areas they are familiar with. Svahn (2004) reported that most German integrated IVNS users rated the correspondence as significant or reasonable (65%), with only a minority (12%) indicating low or insignificant correspondence.

However, in the present study most respondents rated correspondence as moderate (54%), although a higher proportion chose high or very high correspondence (32%) than low or very low correspondence (14%).

Responses to the above item provided a good indication of perceived reliability because respondents had a benchmark (i.e. their own individual preference) against which to rate it, but over time, without such an explicit benchmark, users can also develop conclusions about perceived system reliability. Clearly most respondents in the present study questioned the

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received unreliable guidance. Moreover, over 40% of these respondents report that they have received inaccurate instructions that were dangerous or illegal, in a range of different contexts. Respondents have been instructed to perform prohibited driving maneuvers, or to drive into areas that are prohibited for legal, safety or other reasons. Relatively few respondents have received instructions guiding them into areas for which their vehicle dimensions are unsuitable, although this may be an artifact of the sampling frame, as HGV/ LGV drivers were not specifically targeted.

Inaccurate and unreliable guidance will arise due to a variety of reasons, for instance poor mapping information and erroneous routing algorithms. For example, a recent study showed that software errors are responsible for failures of many IVNS to locate ring roads in cities, so instead they send drivers through increasingly jammed neighbourhood streets typically designed for low traffic volumes (Stichting Onderzoek Navigatiesystemen, 2007). Clearly, the currency of the underlying map data is of particular importance. This survey revealed that inaccurate route guidance instructions were by no means exclusively received by users who had not regularly updated their maps – as 42% of those who had updated maps had still received poor guidance. This is not particularly surprising as internationally, even the most accurate maps will become out-dated very quickly.

Many respondents received free map upgrades. Although it is unlikely that upgrades will ever be universally free, the general consensus of respondents in this survey was that they’re presently overly expensive. The results suggest manufacturers should increase the appeal of map upgrades to younger drivers, although greater foreign mobility (e.g. family holidays, business trips) may also explain why respondents who had updated were significantly older than those who had not.

Chapter 2 showed how several studies had found that IVNS reliability and route guidance accuracy affected system trust (Kantowitz et al., 1994, 1996; Bonsall and Joint, 1991), and that trust is strongly associated with reliance (see Lee and See, 2004). The present study suggests that receiving inaccurate, unreliable and/or dangerous/ illegal route guidance instructions is a pervasive phenomenon affecting the majority of IVNS users. So it is particularly surprising that such a high proportion have followed them on at least one occasion. Two recent studies have also shown the prevalence with which drivers behave this way. In a recent survey (Direct-line, 2008), a UK insurance company found that out of 14

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guiding them the wrong way down a one-way street (incidentally this was one of the most frequent contexts in which respondents in the present study had followed inaccurate route guidance instructions). Varden (2008) also reported that a significant proportion of IVNS users had followed IVNS advice when contradicted by road signs and other people, but the present study provided a much more detailed account of the varied contexts in which this had occurred.

It shows this is a key behavioural adaptation concern that requires further investigation. It would be useful to obtain detailed qualitative accounts of the situations in which drivers receive and follow inaccurate/ unreliable route guidance instructions and any further individual difference variants in their experiences of this. It would also be useful for future research to examine the extent to which this behaviour is caused by a lack of attention or too much trust. Varden`s (2008) finding that respondents followed IVNS advice that contradicted road signs, suggests that respondents were aware of the road signs but chose to rely on the IVNS, and in the present study, a significant proportion of respondents reported that IVNS use had increased or slightly increased their attention to surrounding traffic and road signs. However, due to the subjective nature of self-reported driving behaviour, and because Varden (2008) qualified his findings by suggesting that participant interviews had indicated they hadn’t blindly followed inaccurate instructions, these findings alone cannot be used as sufficient evidence that IVNS users do process road signs (i.e.

favouring the trust/ reliance argument).

In the present study, age was the only variable significantly associated with following inaccurate instructions, and there is research linking it to both reduced attention and increased trust/ over reliance. Increasing age is typically associated with declines in physical and mental ability (see Matthews et al., 2000). It has also been linked to failures in a range of driving performance abilities, including perception, memory and attention. Specifically, it has been associated with impaired performance on tasks of selective (see Rogers, 2000), divided (e.g. Korteling, 1991) and sustained (e.g. Mouloua and Parasuraman, 1995) attention. When performance is not impaired, research suggests that older adults must work harder to maintain similar performance to younger counter-parts (Bunce and Sisa, 2002).

In their model of trust and reliance in automated technology for older adults, Ho et al.

(2005) suggest that complacency (i.e. over-reliance) may be the result of age-related

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making and interpreting stochastic information. These cognitive changes may reduce self-confidence in manual performance. Additionally they suggest that older adults may be less familiar with computer technology and less aware of potential unreliability. A range of driving research using ATIS (Fox and Boehm-Davies, 1998) and gauge warning monitoring tasks (Sanchez, Fisk and Rogers, 2004) has indicated that older drivers trust automated vehicle systems more than their younger counterparts. Using a flight simulation task, Vincenzi and Mouloua (1999) showed that older adults were less likely to notice automation errors and correct for them when they occurred. Ho (2005) also found that older adults placed greater trust in an automated medical management system, and made more errors because they relied on the system too much.

4.6 Summary and implications for behavioural adaptation

This chapter describes a second online survey aimed specifically at IVNS users. It further contributed to the first two aims of the thesis, by elaborating on aspects of behavioural adaptation insufficiently addressed in the driver survey, thoroughly investigating aspects of safety-negative behavioural adaptation that weren’t covered in the driver survey and identifying more individual difference variates in experiences of behavioural adaptation to IVNS, most notably age, driving experience and computing skill. Although study length was also a key concern in the design of the IVNS user survey, in combination with the driver survey it has further addressed the first aim of the thesis and partially addressed the second.

To fully address the second aim it will be necessary for later studies to explore in detail the varied contexts in which behavioural adaptations to IVNS occur.

The IVNS user survey achieved a large sample size. A limitation of the driver survey was that although 440 drivers participated, this included only 157 IVNS users. In the present study, 872 IVNS users participated, enabling identification of several significant trends that affect a wide range of users. In terms of age, it was fairly representative of ordinary UK drivers and IVNS users. Other demographic factors also compared favourably to similar research using more traditional methodologies, with the exception of gender. Both surveys have identified major difficulties in attracting female IVNS users, although as shown above, this is also a significant problem in IVNS user research using traditional methodologies.

As in the previous study, results of the present study must also be interpreted with caution as it concerns self-reported driving behaviour, and as shown previously this means

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by conducting this study online minimised the impression management aspect of social desirability bias, as respondents provided seemingly frank and honest responses to sensitive items (e.g. system interaction while driving), but responses to some items (e.g. distraction potential of IVNS relative to paper maps or ability to learn new routes) may still have been prone to the self-deception aspect of social desirability bias or other response biases such as over- confidence.

Using linguistic analysis of open-ended item responses, this study identified the key components of user satisfaction and dis-satisfaction. The vast majority of responses received (including some responses to the dis-satisfaction item) suggest that most IVNS users are satisfied with their system, and this indicates that acceptance (a pre-requisite for behavioural adaptation) is generally high. The dis-satisfaction responses also provide design insights to help further increase IVNS acceptance.

The results described in detail, the contexts in which drivers use their IVNS. They showed that about a quarter of respondents ventured more frequently into unfamiliar areas, and that most drivers frequently used their systems when travelling in unfamiliar areas. Although these are behavioural effects intended by system designers, in the author`s opinion, they still represent strategic level behavioural adaptation. Further evidence of strategic level behavioural adaptation concerned the frequency with which drivers reported using their systems in only a passive manner while driving in unfamiliar areas and using their systems actively (and passively) even in familiar areas. This could suggest very high trust, if drivers are prepared to delegate control to automation, even when they know where they could be going (i.e. high self confidence).

Based on drivers’ preferences the results also suggested that most drivers prefer to make the strategic decision to utilise both auditory and visual route guidance, and as shown, this could have implications in terms of the extent to which following route guidance instructions distracts the driver. In other words, there could be knock-on effects of their decision to rely on both types of information, in terms of lower level tactical and control level behaviours (e.g. glances, hazard detection).

This study also demonstrated that system interaction (particularly destination entry) while driving is a significant behavioural adaptation issue affecting a large proportion of drivers.

The results illustrated the discrepancies between the perceived risks of different types of

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also highlighted the strong associations between [young] age and [high] computing skills and engagement in this type of behavioural adaptation.

Although reliability and perceived reliability of route guidance information has received some research attention, much less research has considered tendencies to follow inaccurate guidance, which as shown in chapter 2 from a safety perspective could be considered a form of negative tactical level behavioural adaptation. This survey, more than any others to date, documented the wide range and diversity of contexts in which this has occurred. The precise explanation for this phenomenon is presently unclear, the discussion showed how it could be caused by inattention and over trust. The finding that [high] age is associated with the extent to which drivers might follow inaccurate guidance instructions also lends credence to both arguments. In order to fully address the second aim of the thesis, further research is needed to fully explore the contexts in which drivers might follow inaccurate route guidance instructions, by obtaining rich and detailed qualitative accounts.

162 5.1 Introduction

This chapter describes an IVNS-user diary study, in which participants recorded diary entries about their IVNS usage over a two week period and completed questionnaires concerning driver characteristics, as well as a battery of cognitive and attitudinal scales from the literature concerning trust in automation (Jian et al., 2000), automation-induced complacency (Singh et al., 1993), perception, attention (Broadbent et al., 1982; Brown and Ryan, 2003) driving confidence and self-rated driving ability (Parker et al., 2001).

A diary study was used to fully address the second aim of the thesis (i.e. exploration), by comprehensively exploring aspects of behavioural adaptation to IVNS highlighted in the previous chapters, as well as collecting detailed accounts of the specific contexts in which drivers used their IVNS during a 2-week timeframe. As the previous chapters identified several demographic individual difference variables (most notably age and computing skill) that were associated with the frequency with which drivers experienced different types of behavioural adaptation to IVNS, this study also employed several questionnaires and scales to identify any further individual difference variates beyond demographic data alone.