Current topics of interdisciplinary cooperation between engineering and human sciences.

In this article, we highlight current research directions in the Technikpsychologie research area, using the example of the interdisciplinary research work of FAI (Work and Engineering Psychology Research Group at the Technical University of Darmstadt) and the articles included in this special issue. To this end, we relate the articles in this special issue from the research areas of road traffic planning (Hupfer et al.), usable IT security and privacy solutions (Renaud), social aspects of technically mediated communication (Diefenbach), human-centered interface design (Mucha et al.), aviation safety (Santel), human-centered design of autonomous vehicles (Lindner & Stoll), and perceptual psychology-oriented product design (Zandi & Khanh) to current research projects at FAI. Practical Relevance Technical products only offer added value by efficiently supporting users in achieving their goals if they have been developed appropriately for the context of use and the individual characteristics of the users. The human-centered design of-especially technical-products reflects this through an iterative and participatory development process. In this article, we describe nine examples of such human-centered design of technology products. The research results and the methods presented provide insights for developers and decision-makers in the fields of transportation, IT, vehicle development and general product design.

Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores.

Additive manufacturing of casting cores and molds is state of the art in industrial application today. However, improving the properties of chemically bonded casting cores regarding temperature stability, bending strength, and surface quality is still a major challenge. The process of slurry-based 3D printing allows the fabrication of dense structures and therefore sinterable casting cores. This paper presents a study of the slurry-based fabrication of ceramic layer compounds focusing on the drying process and the achievable properties in slurry-based 3D printing of casting cores. This study aims at contributing to a better understanding of the interrelations between the drying conditions in the 3D printing process and the properties of sintered specimens relating thereto. The drying intensity influenced by an IR heater as well as the drying periods are varied for layer thicknesses of 50, 75, and 100 µm. Within this study, a process window applicable for 3D printing of sinterable casting cores is identified and further indications are given for optimization potentials. At layer heights of 75 µm, bending strengths between ~8 and 11 MPa as well as densities of around 50% of the theoretical density were achieved. Since the mean roughness depth Rz is determined to be <30 µm in plane, an application of slurry-based 3D printing in investment casting is conceivable.

Validation and revision of the questionnaire to explore human factors and their technical potential for lower limb prosthetics.

BACKGROUND: A variety of instruments exist to measure human factors for lower limb amputation and prosthesis research. Yet, there is no valid or reliable tool available that focuses on technical potentials. OBJECTIVE: This study aimed to validate and revise the Questionnaire to Explore Human Factors and their Technical Potential. STUDY DESIGN: Cross-sectional study METHODS:: A total of 150 persons with lower limb amputation from Germany participated in the study. Statistical properties, including Cronbach's alpha, item difficulty, item-total correlation, and distribution of missing values were calculated. Thresholds for acceptable psychometric properties were defined, unsuitable items were removed, and problematic items were reviewed regarding formulation. RESULTS: The Cronbach's alpha for subscales within the Questionnaire to Explore Human Factors and their Technical Potential were between 0.72 and 0.89. A total of 56 items showed acceptability, and 14 items had problematic item property values. Four of those items were reformulated, five were excluded, six were left in the scale, and an additional one was added to the scale. CONCLUSION: Evaluation of the Questionnaire to Explore Human Factors and their Technical Potential indicates it exhibits good internal consistency and acceptable psychometric properties. The scale was revised and is recommended to explore aspects of technical prosthesis development. CLINICAL RELEVANCE: Our results show that the revised Questionnaire to Explore Human Factors and their Technical Potential may serve as a reliable and valid means, when designing prostheses, both during development and clinical evaluations and fittings, to assess the technical potential of lower limb prostheses directly according to the needs of users with lower-limb amputations.

The Bayesian causal inference model benefits from an informed prior to predict proprioceptive drift in the rubber foot illusion.

Bayesian cognitive modeling has become a prominent tool for the cognitive sciences aiming at a deeper understanding of the human mind and applications in cognitive systems, e.g., humanoid or wearable robotics. Such approaches can capture human behavior adequately with a focus on the crossmodal processing of sensory information. The rubber foot illusion is a paradigm in which such integration is relevant. After experimental stimulation, many participants perceive their real limb closer to an artificial replicate than it actually is. A measurable effect of this recalibration on localization is called the proprioceptive drift. We investigate whether the Bayesian causal inference model can estimate the proprioceptive drift observed in empirical studies. Moreover, we juxtapose two models employing informed prior distributions on limb location against an existing model assuming uniform prior distribution. The model involving empirically informed prior information yields better predictions of the proprioceptive drift regarding the rubber foot illusion when evaluated with separate experimental data. Contrary, the uniform model produces implausibly narrow position estimates that seem due to the precision ratio between the contributing sensory channels. We conclude that an informed prior on limb localization is a plausible and necessary modification to the Bayesian causal inference model when applied to limb illusions. Future research could overcome the remaining discrepancy between model predictions and empirical observation by investigating the changes in sensory precision as a function of distance between the eyes and respective limbs.

Robotic hand illusion with tactile feedback: Unravelling the relative contribution of visuotactile and visuomotor input to the representation of body parts in space.

The rubber hand illusion describes a phenomenon in which participants experience a rubber hand as being part of their body by the synchronous application of visuotactile stimulation to the real and the artificial limb. In the recently introduced robotic hand illusion (RobHI), a robotic hand is incorporated into one's body representation due to the integration of synchronous visuomotor information. However, there are no setups so far that combine visuotactile and visuomotor feedback, which is expected to unravel mechanisms that cannot be detected in experimental designs applying this information in isolation. We developed a robotic hand, controlled by a sensor glove and equipped with pressure sensors, and varied systematically and separately the synchrony for motor feedback (MF) and tactile feedback (TF). In Experiment 1, we implemented a ball-grasping task and assessed the perceived proprioceptive drift of one's own hand as a behavioral measure of the spatial calibration of body coordinates as well as explicit embodiment experiences by a questionnaire. Results revealed significant main effects of both MF and TF for proprioceptive drift data, but we only observed main effects for MF on perceived embodiment. Furthermore, for the proprioceptive drift we found that synchronous feedback in one factor compensates for asynchronous feedback in the other. In Experiment 2, including a new sample of naïve participants, we further explored this finding by adding unimodal conditions, in which we manipulated the presence or absence of MF and/or TF. These findings replicated the results from Experiment 1 and we further found evidence for a supper-additive multisensory effect on spatial body representation caused by the presence of both factors. Results on conscious body perception were less consistent across both experiments. The findings indicate that sensory and motor input equally contribute to the representation of spatial body coordinates which for their part are subject to multisensory enhancing effects. The results outline the potential of human-in-the-loop approaches and might have important implications for clinical applications such as for the future design of robotic prostheses.

ToxCast EPA in Vitro to in Vivo Challenge: Insight into the Rank-I Model.

The ToxCast EPA challenge was managed by TopCoder in Spring 2014. The goal of the challenge was to develop a model to predict the lowest effect level (LEL) concentration based on in vitro measurements and calculated in silico descriptors. This article summarizes the computational steps used to develop the Rank-I model, which calculated the lowest prediction error for the secret test data set of the challenge. The model was developed using the publicly available Online CHEmical database and Modeling environment (OCHEM), and it is freely available at http://ochem.eu/article/68104 . Surprisingly, this model does not use any in vitro measurements. The logic of the decision steps used to develop the model and the reason to skip inclusion of in vitro measurements is described. We also show that inclusion of in vitro assays would not improve the accuracy of the model.

Application of the rubber hand illusion paradigm: comparison between upper and lower limbs.

The "rubber hand illusion (RHI)" is a perceptual illusion, which allows the integration of artificial limbs into the body representation of a person by means of combined visual and tactile stimulation. The illusion has been frequently replicated but always concerning the upper limbs. The present study verified an analog illusion that can be called the "rubber foot illusion" (RFI). In a conjoint experiment using both a rubber hand and a rubber foot, brushstrokes were applied to the respective real and rubber limb placed alongside the real one. However, only the artificial limb's handling was visible. The brushstrokes were given either synchronously, with a delay of ±0.5 s, or without tactile stimulation of the real limb. Questionnaire data and the proprioceptive drift towards the rubber limb (determined by calling on the subjects to show where they locate their unseen limb) defined the illusion strength. Results revealed that the illusion was induced in both limbs with comparable strength, but only in the synchronous condition.

Theoretical implementation of prior knowledge in the design of a multi-scale prosthesis satisfaction questionnaire.

BACKGROUND: In product development for lower limb prosthetic devices, a set of special criteria needs to be met. Prosthetic devices have a direct impact on the rehabilitation process after an amputation with both perceived technological and psychological aspects playing an important role. However, available psychometric questionnaires fail to consider the important links between these two dimensions. In this article a probabilistic latent trait model is proposed with seven technical and psychological factors which measure satisfaction with the prosthesis. The results of a first study are used to determine the basic parameters of the statistical model. These distributions represent hypotheses about factor loadings between manifest items and latent factors of the proposed psychometric questionnaire. METHODS: A study was conducted and analyzed to form hypotheses for the prior distributions of the questionnaire's measurement model. An expert agreement study conducted on 22 experts was used to determine the prior distribution of item-factor loadings in the model. RESULTS: Model parameters that had to be specified as part of the measurement model were informed prior distributions on the item-factor loadings. For the current 70 items in the questionnaire, each factor loading was set to represent the certainty with which experts had assigned the items to their respective factors. Considering only the measurement model and not the structural model of the questionnaire, 70 out of 217 informed prior distributions on parameters were set. CONCLUSION: The use of preliminary studies to set prior distributions in latent trait models, while being a relatively new approach in psychological research, provides helpful information towards the design of a seven factor questionnaire that means to identify relations between technical and psychological factors in prosthetic product design and rehabilitation medicine.

Movement transformation on multi-touch devices: Intuition or instructional preparation?

Multi-touch technology is a key part of computer interaction today, yet little is known about the distinction between direct and indirect input devices in terms of intuitive interaction. An experimental study aims to identify the difficulties of interaction with indirect multi-touch devices by applying the action regulation theory and the principle of movement transformation to common computer tasks involving gesture utilization. An analysis of the data acquired from 54 subjects working with an Apple Magic Trackpad implies that gestures on indirect multi-touch devices are not utilized intuitively without instructions that bypass conceptual difficulties of indirect gesture usage. It is shown that gesture use influences product assessment measured by User Experience questionnaires and that prior experience with direct multi-touch devices does not influence gesture usage or product assessment. We advise that product developers utilize video instructions to create a sense of intuitive interaction.

Prediction-driven matched molecular pairs to interpret QSARs and aid the molecular optimization process.

BACKGROUND: QSAR is an established and powerful method for cheap in silico assessment of physicochemical properties and biological activities of chemical compounds. However, QSAR models are rather complex mathematical constructs that cannot easily be interpreted. Medicinal chemists would benefit from practical guidance regarding which molecules to synthesize. Another possible approach is analysis of pairs of very similar molecules, so-called matched molecular pairs (MMPs). Such an approach allows identification of molecular transformations that affect particular activities (e.g. toxicity). In contrast to QSAR, chemical interpretation of these transformations is straightforward. Furthermore, such transformations can give medicinal chemists useful hints for the hit-to-lead optimization process. RESULTS: The current study suggests a combination of QSAR and MMP approaches by finding MMP transformations based on QSAR predictions for large chemical datasets. The study shows that such an approach, referred to as prediction-driven MMP analysis, is a useful tool for medicinal chemists, allowing identification of large numbers of "interesting" transformations that can be used to drive the molecular optimization process. All the methodological developments have been implemented as software products available online as part of OCHEM (http://ochem.eu/). CONCLUSIONS: The prediction-driven MMPs methodology was exemplified by two use cases: modelling of aquatic toxicity and CYP3A4 inhibition. This approach helped us to interpret QSAR models and allowed identification of a number of "significant" molecular transformations that affect the desired properties. This can facilitate drug design as a part of molecular optimization process. Graphical AbstractMolecular matched pairs and transformation graphs facilitate interpretable molecular optimisation process.

Recycling behaviour in healthcare: waste handling at work.

This article reviews the motivational factors for environmental behaviour in general, presenting a case study on recycling disposable plastics in hospitals. Results show that 90% of over 600 employees from six analysed hospitals in Germany reported that the recycling of disposable plastics on the wards makes sense from an environmental and economic point of view. The case study reports an assessment of recycling attitudes and problems of hospital staff, mainly nurses. Employees in eco-certified hospitals were much more satisfied and reported fewer problems with the recycling system. The gender effect was significant only for saving energy, while age correlated with nearly all reported pro-environmental behaviour at home. At work, the mere introduction of a recycling system was insufficient to achieve good recycling results. Based on the study findings, recommendations are given aimed at improving the safety and sustainability of the recycling system.

Critical Incident Stress Management (CISM) in complex systems: cultural adaptation and safety impacts in healthcare.

In complex systems, such as hospitals or air traffic control operations, critical incidents (CIs) are unavoidable. These incidents can not only become critical for victims but also for professionals working at the "sharp end" who may have to deal with critical incident stress (CIS) reactions that may be severe and impede emotional, physical, cognitive and social functioning. These CIS reactions may occur not only under exceptional conditions but also during every-day work and become an important safety issue. In contrast to air traffic management (ATM) operations in Europe, which have readily adopted critical incident stress management (CISM), most hospitals have not yet implemented comprehensive peer support programs. This survey was conducted in 2010 at the only European general hospital setting which implemented CISM program since 2004. The aim of the article is to describe possible contribution of CISM in hospital settings framed from the perspective of organizational safety and individual health for healthcare professionals. Findings affirm that daily work related incidents also can become critical for healthcare professionals. Program efficiency appears to be influenced by the professional culture, as well as organizational structure and policies. Overall, findings demonstrate that the adaptation of the CISM program in general hospitals takes time but, once established, it may serve as a mechanism for changing professional culture, thereby permitting the framing of even small incidents or near misses as an opportunity to provide valuable feedback to the system.

Human factors in safety and business management.

Human factors in safety is concerned with all those factors that influence people and their behaviour in safety-critical situations. In aviation these are, for example, environmental factors in the cockpit, organisational factors such as shift work, human characteristics such as ability and motivation of staff. Careful consideration of human factors is necessary to improve health and safety at work by optimising the interaction of humans with their technical and social (team, supervisor) work environment. This provides considerable benefits for business by increasing efficiency and by preventing incidents/accidents. The aim of this paper is to suggest management tools for this purpose. Management tools such as balanced scorecards (BSC) are widespread instruments and also well known in aviation organisations. Only a few aviation organisations utilise management tools for human factors although they are the most important conditions in the safety management systems of aviation organisations. One reason for this is that human factors are difficult to measure and therefore also difficult to manage. Studies in other domains, such as workplace health promotion, indicate that BSC-based tools are useful for human factor management. Their mission is to develop a set of indicators that are sensitive to organisational performance and help identify driving forces as well as bottlenecks. Another tool presented in this paper is the Human Resources Performance Model (HPM). HPM facilitates the integrative assessment of human factors programmes on the basis of a systematic performance analysis of the whole system. Cause-effect relationships between system elements are defined in process models in a first step and validated empirically in a second step. Thus, a specific representation of the performance processes is developed, which ranges from individual behaviour to system performance. HPM is more analytic than BSC-based tools because HPM also asks why a certain factor is facilitating or obstructing success. A significant need for research and development is seen here because human factors are of increasing importance for organisational success. This paper suggests integrating human factors in safety management of aviation businesses - a top-ranking partner of technology and finance - and managing it with professional tools. The tools HPM and BSC were identified as potentially useful for this purpose. They were successfully applied in case studies briefly presented in this paper. In terms of specific safety-steering tools in the aviation industry, further elaboration and empirical study is crucial. Statement of Relevance: The importance of human factors is recognised by operators at the sharp end of aviation, where flights are conducted or coordinated. At the blunt end, measurement tools are needed to manage operational resources.

A report on the evaluation of the First European Conference on Critical Incident Stress Management organized by the European Office of the International Critical Incident Stress Foundation.

The International Critical Incident Stress Foundation (ICISF) established an office in Europe in 2004. The ICISF European Office (EO) held its first ICISF European Conference on Critical Incident Stress Management on September 27th 2008. The conference was formally evaluated and the results are reported in this article. 140 participants from seventeen different European nations were counted In open-ended answers and standard rating scales, 83 participants gave feedback on the conference. They were asked about the relevance of the conference, the theory-to-practice transfer learning effects, quality of the presentations, organization, location and wishes to future conferences. The results were positive in all respects. They should focus on specific organizations or professional groups (e.g. rescue services) and take place in the falls of odd years.

Cultural differences in dealing with critical incidents.

This article discusses the cultural aspects of High Reliability Organizations (HROs), such as air navigation services. HROs must maintain a highly professional safety culture and constantly be prepared to handle crises. The article begins with a general discussion of the concept of organizational culture. The special characteristics of HROs and their safety culture is then described. Finally the article illustrates how Critical Incident Stress Management (CISM) is becoming an ingrained feature of the organizational culture in air traffic control systems. Critical Incident Stress Management is a prevention program that can successfully guard against the negative effects of critical incidents. The CISM program of DFS (Deutsche Flugsicherung) was recently evaluated by the University of Copenhagen. This evaluation not only confirmed the successful prevention of negative effects at the operation's employee level (especially air traffic controllers), but also showed a sustained improvement of its safety culture and its overall organizational performance. The special aspects of cross-cultural crisis intervention and the challenges it faces, as well as the importance of prevention programs, such as CISM, are illustrated using the examples of two aircraft accidents: the crash landing of a calibration aircraft and the Lake Constance air disaster.

Economic evaluation of CISM--a pilot study.

This paper reports the implementation of the Critical Incident Stress Management (CISM) Program with the German Air Traffic Control Services (DFS). Particular attention is paid to the application of CISM services to a population of air traffic controllers. An extended economic efficiency evaluation was conducted for the European Organization for the Safety of Air Navigation (Eurocontrol) Brussels. Questionnaires and interviews were obtained from forty-seven air traffic controllers (ATCOs), thirteen CISM peers, and the program manager. The collected data describe the goals of the program and their achievement, program implementation, costs, and benefits. The results revealed that after five years the program's estimated fiscal benefits had exceeded the costs (break-even). Moreover, it had improved the safety culture within DFS in many ways. For this reason, controllers who never consulted a peer reported many benefits of the program. They believed that having the program was a good idea as a back-up support in case they would ever need it.