After controlling for car length, brand status, and car price, driver seat space remained a positive predictor of illegal parking

Does size matter? Spacious car cockpits may increase the probability of parking violations. Felix C. Meier, Markus Schöbel & Markus A. Feufel. Ergonomics, Volume 61, 2018 - Issue 12, Pages 1613-1618, Oct 26 2018. https://doi.org/10.1080/00140139.2018.1503727

Abstract: Cockpit design is a core area of human factors and ergonomics (HF/E). Ideally, good design compensates for human capacity limitations by distributing task requirements over human and interface to improve safety and performance. Recent empirical findings suggest that the mere spatial layout of car cockpits may influence driver behaviour, expanding current views on HF/E in cockpit design. To assess the reliability of findings showing that an expansive driver seat space predicts parking violations, we replicated an original field study in a geographically and socio-culturally different location and included an additional covariate. After controlling for car length, brand status, and car price, driver seat space remained a positive predictor of illegal parking. This suggests that the spatial design of vehicle cockpits may indeed have an influence on driver behaviour and may therefore be a relevant dimension to be included in research and applications of HF/E in cockpit design.

Practitioner summary: In car cockpit design, ergonomists typically focus on optimising human–machine interfaces to improve traffic safety. We replicate evidence showing that increasing physical space surrounding the driver relates to an increased probability of parking violations. This suggests that spatial design should be added to the ergonomist's toolbox for reducing traffic violations.

Keywords: Embodiment, expansive body postures, traffic safety, cockpit design, parking violations

4 Discussion
Similar to the findings of Yap and colleagues (2013) our study shows that driver seat space predictsthe likelihood of parking violations. This effect could be replicated in a different cultural (Germany vs. US) and urban setting (the rural town of Offenburg vs. the metropolis New York City) focusing ona broad variation of parking violations identified by professional inspectors.Theeffect statistically persisted, even when controlling for car brand status, car length, and car price, the latter of which is also a significant predictor forparking violations.

These findings suggest that driving behaviour and traffic safety may not only be influenced by interactions between the person behind the wheel and interface design, but also by the spatial dimension of the driver'scar cockpit. Furtherresearchinto the effectof driver seat space on behavioural processes(e.g., body postures, risk taking, andviolations)might inform future HF/E research on cockpit design. Relatedly, our results also imply that safe cockpit design should also move beyond the standard error categories of slips, lapses and mistakes,and should also pay attention to violations. Although ample studies investigate the relationship between psychological factors and traffic violations (e.g.,Ba et al. 2016), there are only few HF/E studies on the effect of cockpit designon traffic violations to date (e.g., Aliane et al. 2014). The present study suggests anewavenue for HF/E to systematicallyinvestigate traffic violations in relation to the spatial dimensionof cockpit design. More such studies may have the power to advance the current understanding of traffic violations bycomplementingpsychological sources of violations with those that are located in the environment (Reason 1990).

We are aware that the behavioural effects of body postures are fiercely debated in the literature. Given that this debate is ongoing,there is no clear-cut explanatory accountfor our results. But even ifwecannot explain the effect of body postures on parking violations with our observational design, our results may help trigger additional research for a better understanding of the relationship between driver seat space and traffic violations.

Our study included additional control variables (i.e., car price) compared to the original study by Yap and colleagues. However, there are also other variables, which shouldbe consideredin future studies. For instance, tall or heavy drivers will have different individual seat spaces compared to short and slender drivers. Also, individual seat configuration, that is, whether a seat is adjusted closer to or further away from the steering wheel, influences individual seat spaceand, therefore, body postures. Moreover, Carney, Cuddy, and Yap (2015) discuss that also the time a person remains in a certain posturemay change its effects. Whereas experimental manipulations of body postures forced participants to hold a posture oneminute (Carney, Cuddy, and Yap 2010) or threeminutes (Ranehill et al. 2015), it can be assumed that participants in our study did not “hold” but selected a posture that felt comfortable or natural, potentially for an extended period of time. Clearly, more research is needed to work out both the magnitude and the causal explanations of body posture effects as well astheir relevance for cockpit design. Our results imply that it is worthwhile investigating the thus faru nder-researched impact of driver seat space on traffic behaviour. HF/E is well equipped to follow up on these findings.