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Background An atrio-esophageal fistula is an exceedingly rare but devastating complication of atrial fibrillation (AF) ablation procedures. Delays to diagnosis and definitive treatment herald a poor prognosis, with the development of catastrophic neurological injury or death secondary to cerebral air emboli. A high level of suspicion is essential to improve recognition of this rare but devastating condition. Case Report A 59-year-old man presented to the emergency department with an acute stroke and reduced consciousness. This presentation was preceded by an uncomplicated AF ablation 19 days prior and a subsequent emergency department attendance within a few days of his procedure, where he had presented with a history of new chest pain and reflux symptoms. Imaging revealed intra-cranial and intra-cardiac air, which was attributed to an uncontrolled atrio-esophageal fistula. Treatment options were limited by the patient's clinical instability and the patient was eventually palliated after developing catastrophic brain injury due to extensive cerebral air emboli. Why Should an Emergency Physician Be Aware of This? Patients typically first present to the emergency department with new symptoms of either gastroesophageal reflux or chest pain, therefore, early recognition by emergency physicians is vital. Characteristic symptoms alongside a recent history of a cardiac ablation procedure should prompt additional diagnostic imaging to look for evidence of an atrio-esophageal fistula.

As multiple representations are common in math education, we examined different combinations of representations (text, formula, graphic) in the field of propositional logic. In two experiments, we investigated whether participants benefit from multiple representations, and whether the kind of representational combination affects performance. For the first experiment, 146 university students were divided into six groups: two single-representation groups (text or formula), three dual-representation groups (all possible pairs), and one triple-representation group. Results indicate that the combination of multiple symbolic representations (text + formula) was as helpful as combining analog and symbolic representations (text + graphic and text + formula + graphic): the participants provided with all such types of multiple representations outperformed all single representation groups. In a second experiment (N = 19, within-subjects) we compared the gaze behavior when working with multiple symbolic representations (text + formula) or combined symbolic and analog representations (text + graphic). The results demonstrate that text was the one representation that was attended most and can therefore be regarded as the reference representation in all useful combinations. Even though fewer gaze switches were observed between text and formulas than between text and graphics, performance (time on task and accuracy) did not differ. This research emphasizes the importance of various forms of multiple representations in mathematics learning and assessment, and sheds light on how different kinds of representations and their combinations are processed.

Hazard perception is one of the few quantifiable components of driving competency that can explain the high crash risk of novice drivers (see Horswill & McKenna, 2004). Some studies focused on investigating the stimulus part of hazard perception items by comparing several design features of the displayed traffic scenarios (e.g. Malone et al., 2012; Scialfa et al., 2013). Other empirical studies have been conducted to address the reaction part of hazard perception items (e.g. Vlakveld, 2014). Among others, existing hazard perception tests differ with respect to the ecological validity – the similarity to real-world demands – of the task that has to be completed by the participants (simple reaction, hazard localization, simulated driving, etc.). Based on the findings of general expertise research (see Glaser & Chi, 1988), the hypothesis of the present experiment was that an increased ecological validity of a hazard perception task has a positive effect on the magnitude of performance differences between more and less experienced drivers. 104 learner drivers and 51 experienced drivers were randomly assigned either to a less ecological valid version (multiple choice task) or a higher ecological valid version (reaction task) of a hazard perception test. In both conditions, the same 20 animated hazardous or non-hazardous traffic scenarios were presented. Overall, the experienced drivers outperformed the learner drivers. Principally, both of the applied versions of the test provided a criterion valid measure of driving expertise. However, increasing the ecological validity of the test by using a reaction task was especially beneficial for certain types of scenarios, leading to higher expertise-related differences. In addition, the reaction task provides response time measure as a further valid performance indicator. This allows the identification of those participants who are indeed able to detect a hazard in a certain scenario, but still have deficits in response time, compared to more experienced drivers. According to the present study, it is recommended to choose the reaction task over the multiple choice task to test hazard perception. Whether a further increase in ecological validity of the task would be useful, should be tested empirically in future research.

Hazard perception – the driver's ability to identify road hazards – is one of the few measurable aspects of driving competency that can explain the high accident risk of some groups of drivers [1,2]. Hazard perception tests differ regarding several features. Only a few empirical studies have been conducted to systematically compare different design features of hazard perception tests as e.g. the presentation mode (static vs. dynamic) of the included traffic scenarios [3,4]. Beside the variation of the stimulus material, hazard perception tests differ regarding the kind of task that has to be fulfilled by the participants. In general, experts outperform novices more clearly with increasing ecological validity of a task – its similarity to the demands of a certain domain [5]. As an empirical indicator of validity is a clear difference between experts and novices, ecological valid tasks are expected to increases the quality of a test. The aim of the present study was to investigate whether the criterion validity of a hazard perception test can be enhanced by the application of an ecological valid task. 35 learner drivers and 31 experienced drivers were presented 21 animated driving scenarios that did or did not contain a potential hazard. One half of the participants were to react to hazards within the animation (high ecological validity) whereas the others worked on multiple-choice questions provided after the presentation (low ecological validity). The ANOVA revealed a main effect of expertise: experts scored highest. Moreover, a main effect of the task's ecological validity could be found: the multiple-choice task facilitated the test. No interaction between expertise and ecological validity could be found. The results indicate that both tasks lead to valid measures. Contrary to our expectations, the ecological validity of the task did not influence the criterion validity. Further research should be conducted e.g. in order to investigate, whether a further increase of ecological validity – e.g. by simulated driving – results in extended expert-novice differences.

Novice drivers have a high collision risk compared to more experienced drivers. The optimization of driving assessment's validity should lead to a better identification of those examinees that need further training before solo driving. The aim of the present two studies was to find out whether the integration of animated traffic scenarios can enhance some quality aspects of selected multiple choice items of the official German driving test. For the first study, we developed a static version of a set of multiple choice questions each containing a computerized still picture of a traffic scenario and a dynamic version that included animated instead of still pictures of the same situations. Driving novices (n=57) and experts (n=63) were presented 22 items either in the static or in the dynamic version. Only the novices benefited from the dynamic presentation. Fifty novices and 50 experts participated in a second longitudinal study including three measurements with parallel tests of the dynamic testing materials at intervals of three to four months. The novices, who were currently attending driving school, improved over time whereas the experts' performance remained stable. The results indicate that animation has positive effects on some quality aspects of driving assessment, but the problem of low criterion validity has to be addressed by the means of further approaches. Language: en