them with new structures that make better use of existing cues, or take advantage of more subtle cues that might not have been apparent previously. This raises the possibility that, in some instances, experienced motorcyclists might develop unsafe associa- tions between certain visual cues and the required behaviour (akin to ‘bad habits’). These perceptual-response mappings would then need to be relearned during the transition to becoming an advanced rider. A similar process has previously been noted in car drivers. Duncan, Williams and Brown [29] compared novice car drivers’ performance with experienced and advanced car drivers (with the latter group having taken advanced training with the Institute of Advanced Motorists). On a number of behaviours, they found novice drivers to behave more appropriately than experienced drivers, including mirror checks and appropriate braking on approach to junctions. As with the current study, Duncan et al. found occasions when the advanced group had more in common with the novices than the experienced group. They suggested that such differences tended to occur where negative feedback was unlikely to occur. For instance, while the grinding of gears provides excellent feedback on which to base improvements in changing gear, failing to look in a mirror will only become apparent if a near or actual collision occurs because of the omission. The role of advanced training is therefore to provide the feedback that can only otherwise be obtained at the risk of injury and collision. This result was mirrored in recent research conducted in our laboratory which assessed how well car drivers spot approaching motorcycles at t-junctions. Eye movement behaviour suggested that experienced car drivers might actually be more susceptible than novices to a ‘‘Look But Fail To See’’ error than novice car drivers [30]. As with the work of Duncan et al. [29], this suggests that over-learned expectancies borne out of years of experience may prove detrimental to road safety in specific situations. Whilst we would not venture to argue that our sample of novice riders are therefore safer than our sample of experienced riders, it does seem to be the case that they responded more cautiously in some situations. This may, in part, be due to the recent training they had prior to passing their test, or a healthy anxiety of hazards coupled with a lack of confidence in their own abilities. Certainly it appears that the additional training received by our sample of advanced riders has resulted in an overall safer approach to these bends. While one cannot rule out the argument of self-selection in our advanced rider group (i.e. a particular type of motorcyclist might opt for advanced training), it seems plausible that the advanced training has resulted in previously experienced riders overcoming bad habits by relearning the relationship between particular cues and appropriate riding behaviour on bends, therefore making the transition to an expert rider. Conclusion What do the results suggest regarding the causes of crashes on bends that do not involve other vehicles? The Clarke et al. study [5,6] of police crash reports argues for inappropriate speed or under-steering to be the primary causes of such crashes. However, the current results do not support this. Assuming advanced riders display the safest behaviour, we cannot argue that the other groups adopted an inappropriate speed, as speeds were similar across all groups. Similarly we have no evidence for under-steering in the novice or experienced groups. Instead, an alternative cause is suggested. Our non-advanced riders took a more pronounced References Motorcyclist Behaviour on Bends racing line through the apex of a bend with constant curvature. If however the bend did not have constant curvature then riders might misjudge the location of the apex (i.e. perceive it be nearer) and thus find themselves drifting back out too soon, or being caught out in a tightening bend by entering too fast. This situation could either lead to the rider running off the curve, or losing control as they suddenly attempt to correct their speed and/or position. Similarly sharper bends may be mis-perceived resulting in an inappropriate racing line, with similar consequences, which might partly explain the greater number of crashes on high- curvature bends [7–10]. We should be clear, however, that we are not arguing that speed is not a factor in crashes on bends. Inappropriate speed will certainly contribute to such incidents; it is merely the case that our current sample did not show inappropriate speed (when compared to advanced riders). One might argue that this suggests that the simulator did not evoke realistic behaviour, as it intuitively seems that speed must be an important factor. However in the absence of any previous literature pertaining to studies of simulated riding in curves, it would be unfair to dismiss the results on the grounds of intuition, or on the basis of accident reports which contain a degree of inference. While it is true that no simulator can perfectly recreate the real world, such ‘face validity’ is less important than ensuring that the particular aspects of the environment that are required for a particular task are adequately represented. For instance, one extremely influential paper that addressed the visual cues required for steering used an Acorn Archimedes computer displaying only three white lines on a black screen (one for the horizon, and two to represent road edges) [31]. While it remains a possibility that the current simulator does not recreate one particularly vital cue to curve negotiation, we argue that it is more likely that the experimental design may account for a failure to identify speed differences. The design of the bends (with high banking and low visibility), plus the fact that each bend was always preceded by an identical bend, may have reduced the variance in speed across the groups. This is not a limitation of the simulation, but a feature of the experimental design. Future research can vary the curvature and visibility through bends, and what road features precede entry into the bend. It is likely that some future conditions may indeed evoke speed differences between groups, though the current demands did not and we have no reason to believe that the simulator is the cause of this effect. The evidence that points towards speed and under-steering on bends comes from post-crash inferences based on police interviews and crash-site analysis [5,6], while the current evidence for problems with the racing line comes from direct behavioural observation of a limited sample in a virtual world. While we do not reject the likelihood of speed and under-steering contributing to collisions in certain types of bends, we believe that we have demonstrated that inappropriate lane positioning may also be an important factor. Author Contributions Conceived and designed the experiments: DC AWS. Performed the experiments: EC. Analyzed the data: EC. Contributed reagents/materials/ analysis tools: AWS EC. Wrote the paper: EC DC. 1. Department for Transport (2010a) Road traffic by vehicle type, Great Britain: 1950– 2009 (miles). Available: http://www.dft.gov.uk/pgr/statistics/datatablespublica- tions/roads/traffic/annual-volm/tra0101.xls via the Internet. Accessed 28 Jun 2011. 2. Department for Transport (2010b) Road traffic and speed statistics - 2009. Available: http://www.dft.gov.uk/pgr/statistics/datatablespublications/roads/ traffic/via the Internet. Accessed 28 Jun 2011. PLoS ONE | www.plosone.org 16 January 2012 | Volume 7 | Issue 1 | e29978