Skip to main content

MINI REVIEW article

Front. Psychol., 22 September 2022
Sec. Theoretical and Philosophical Psychology
This article is part of the Research Topic Insights In: Theoretical and Philosophical Psychology View all 14 articles

The time is ripe for robopsychology

Christian U. Krgeloh
Christian U. Krägeloh1*Jaishankar BharatharajJaishankar Bharatharaj2Jordi Albo-CanalsJordi Albo-Canals3Daniel HannonDaniel Hannon4Marcel HeerinkMarcel Heerink5
  • 1PAIR Lab New Zealand, Auckland University of Technology, Auckland, New Zealand
  • 2PAIR Lab India, Bharath Institute of Higher Education and Research, Chennai, Tamil Nadu, India
  • 3Lighthouse Disruptive Innovation Group, LLC., Cambridge, MA, United States
  • 4Department of Mechanical Engineering, Tufts University, Medford, MA, United States
  • 5Saxion University of Applied Sciences, Enschede, Netherlands

As robotic applications become increasingly diverse, more domains of human lives are being involved, now also extending to educational, therapeutic, and social situations, with a trend to even more complex interactions. This diversity generates new research questions that need to be met with an adequate infrastructure of psychological methods and theory. In this review, we illustrate the current lack of a sub-discipline in psychology to systematically study the psychological corollaries of living in societies where the application of robotic and artificial intelligence (AI) technologies is becoming increasingly common. We thus propose that organized efforts be made toward recognition of robopsychology as a sub-discipline so that the field of psychology moves away from isolated publications of robot- and AI-related topics to a body of knowledge that is able to meet the demands for change, as the world is preparing for the Fourth Industrial Revolution. We propose a definition of robopsychology that not only covers the study of the effects of robots on human behavior, but also of robots and AI themselves, as well as acknowledging how this sub-discipline may eventually be fundamentally changed through robots and AI. In this sense, our definition mirrors an already existing definition of the field of robophilosophy.

Introduction

While the word robot has only first appeared in the early 1920s through Karel Čapek’s science fiction play R.U.R. (Rossum’s Universal Robots; Čapek, 2004), the idea of self-moving machines, or automata, has featured in myths and stories that go back three millennia and are found in many parts of the world (Mayor, 2018). Throughout history, there have also been many independent attempts to create actual automata, such as water-powered organs or mechanized beasts and androids (Cave and Dihal, 2018). Of course, it was not until the rapid technological progress of the 20th century that robots became more wide spread. For example, the adoption of robotic technology in the automotive manufacturing industry resulted in dramatic increases in cost-efficiency and production quality (Karabegović, 2016). Due to the precision they provide, robots have also become commonplace in medical contexts such as in surgery (Lane, 2018).

Most individuals would rarely encounter industrial and surgical robots, and if so, only witness the very specific functions that these robots provide. This is in contrast with the notion of robots as embodied intelligent and autonomous agents and particularly with portrayal in media and film, where robots often appear as highly sophisticated and with the potential to lead to utopian or dystopian scenarios (Mubin et al., 2019). Fact-based media reporting has been shown to increase positive attitudes and trust in robots (Savela et al., 2021), and actual encounters with robots also have the potential to alleviate much of the anxiety and wariness that people may have. While instances of robotic hotel check-in and room service (Fuentes-Moraleda et al., 2020) or robotic chefs in restaurants (Fusté-Forné, 2021) may still be viewed as having primarily entertainment value, systematic attempts have increasingly been made to apply robots to provide psychosocial or educational benefits for humans. Robots have thus been used to provide companionship for older people (Gasteiger et al., 2021), robot-enhanced psychotherapy (Costescu et al., 2014), or to assist in learning and teaching (Belpaeme et al., 2018). As human-robot interactions are appearing to become more lively and reciprocal, more effort is directed at studying the psychological reactions of human users in order to optimize this experience. Research has thus explored the effects of a range of variables such as robot morphology (Mara et al., 2022), voice (Dong et al., 2021), or nonverbal behavior (Zinina et al., 2020). Recent research has even explored the extent to which what the appearance of robots may be racialized with the potential to perpetuate racial stereotypes (Bartneck et al., 2018).

The trend towards increased relevance of robots in people’s lives accelerates the need to understand the variables that influence the quality of human-robot interactions as well as their psychological corollaries. While a solid body of research has already emerged (Siciliano and Khatib, 2016), new research questions continue to be posed, particularly the extent to which such applications are motivated by or fulfil humans’ psychological needs. As shown by robotic pets (Melson et al., 2009), robotic romance (Viik, 2020), sex robots (Döring et al., 2020), or robots to provide spiritual and religious support (Trovato et al., 2021), human-robot interactions are increasing in complexity, thus connecting robot research with the same psychological models and theories that are used to explain social behaviors among humans, such as attachment theory (Pozharliev et al., 2021) or social identity theory (Edwards et al., 2019). The purpose of the present review was to explore the extent to which there are any existing sub-disciplines in psychology devoted to the study of topics involving robots. Using a state-of-the-art review approach (Grant and Booth, 2009) with a systematic search strategy, we provided an outline of the landscape of psychological sub-disciplines. Not being based on any previous theories or hypotheses, this review followed an inductive approach (Watson et al., 2018).

A review of the representation of the study of robots in existing sub-disciplines of psychology

At the time of writing this review (May 2022), the journal Frontiers in Psychology listed 32 sub-disciplines or sub-fields of psychology to structure the content of its articles (Frontiers in Psychology, 2022). We present these in Table 1, together with potential sub-discipline names expressed through the 54 divisions recognized by the American Psychological Association (APA) at the time of writing this review (APA, 2022a). APA notes that some of the divisions represent special interest groups rather than sub-disciplines. However, for the purposes of identifying representation of robotics-related research in psychology, including special interest groups in addition to sub-disciplines provides a more comprehensive analysis. Additionally, we searched through the APA literature database PsycInfo for journal titles that could indicate a sub-discipline that may have recently emerged or is too small to have been recognized yet as a sub-field in psychology. We searched this psychology database containing nearly 2,300 journals for the word stem “psycho” to identify potential sub-discipline names that are expressed either by a preceding adjective other than a geographical location (e.g., applied psychology), a preceding noun (e.g., community psychology), or by a prefix (e.g., ecopsychology). The presence of two adjectives was considered to be too specific and indicative of a further sub-categorization within a sub-discipline. For example, applied social psychology was not included as it was treated as a further division of social psychology. If a name contained two adjectives (e.g., reproductive and infant psychology), the entry was presented like that, unless both adjectives had already resulted in a separate entry. Synonyms or very similar terms were still retained as separate entries, such that both child psychology and pediatric psychology were included. The search was conducted by the first author using coding for relevance, which was verified independently by the second author. Any uncertainty was resolved by discussion. In total, we list 127 entries in Table 1, with information on where they were sourced from.

TABLE 1
www.frontiersin.org

Table 1. Sub-disciplines and special interest groups of psychology as presented by Frontiers in Psychology, APA, and in academic journal titles.

None of the 127 entries in Table 1 make any reference to robots. APA Division 21 (Applied Experimental and Engineering Psychology) might initially appear to have some relevance to robotics but is very broadly worded as promoting “the development and application of psychological principles, knowledge, and research to improve technology, consumer products, energy systems, communication and information, transportation, decision making, work settings and living environments” (APA, 2022b). While three journal titles in PsycInfo contained the word “robot,” none of these are representative of what may be considered a relevant sub-discipline of psychology. ACM Transaction of Human-Robot Interaction is described on its homepage (Association for Computing Machinery, 2022) to be an interdisciplinary journal that also welcomes submissions from behavioral and social sciences. Intelligent Service Robotics (Springer, 2022a) is focused on assistive functions of robots, making some mention of the relevance of cognitive science, and International Journal of Social Robotics (Springer, 2022b) is presented as an interdisciplinary journal that does not mention psychology specifically.

Discussion: Robot psychology, robotic psychology, or robopsychology?

The list in Table 1 indicates that there is currently no sub-discipline in psychology that can be considered to be giving robots special attention, either as experimental subjects or by studying their effects on human behavior. Of course, this does not mean that a potential psychological sub-discipline may not already have some sort of presence in the literature through individual publications. What are some potential sub-discipline names mentioned in this work and what do these names suggest about the way in which robots are studied? When searching the academic literature (using GoogleScholar) for “robot psychology,” a small number of articles can be found. This includes a technical note by Konolige (1985) where experimental robot psychology is purported to be about “analyzing the design of a robot agent’s cognitive processes” (p. 2). Gallagher (2013) referred to robot psychology when describing a robot’s understanding of its own propositional attitudes (as equivalent to folk psychology for humans), and Nitsch and Popp (2014) used the term in the context of describing how robots as social agents need to be able to “predict human intentions and actions and display behavior that is appropriate to that context” (p. 622). Therefore, just like animal psychology is about understanding the behavior of animals, robot psychology is focused on robots only and thus not aspects related to the human perspective when interacting with robots.

A suitable alternative to robot psychology is robotic psychology. While this phrase has also been mentioned only very little in the literature, it has been clearly defined as the study of “individual differences in people’s interactions with various robots, as well as the diversity of the robots themselves, applying principles of differential psychology to the traditional fields of human factors and human–computer interactions” (Libin and Libin, 2004, p. 1792). The authors contrasted robotic psychology with robopsychology, which they defined as “a systematic study of compatibility between people and artificial creatures” as well as the study of “psychological mechanisms of the animation of the technological entity which result in a unique phenomenon defined as a robot’s ‘personality’” (p. 1792). Unlike robotic psychology, which “focuses on the psychological significance of person-robotic creature communication” (Libin and Libin, 2004, p. 1792), the focus of robopsychology is thus on the understanding of robot behavior. This usage of the term is consistent with how it was first used when introduced as the name of a fictional science in short stories by Isaac Asimov in 1950 (Bátfai, 2020).

While some studies (Servick, 2019) have interpreted the term robopsychology in a way consistent with the definition above, other researchers have used the term interchangeably with robotic psychology (Duradoni et al., 2021; Linz Institute of Technology, 2022). In the absence of any well-established or consistent use of any of these terms, a future sub-discipline in psychology related to robots may still decide on a suitable name. In our view, the term robopsychology is preferable as it can be easily identified alongside the already established field of robophilosophy (Tzafestas, 2016) – the “philosophy of, for, and by social robotics” (Seibt, 2018, p.390). Philosophy of social robotics is seen as the reflective activities about conceptual implications of investigating human-robot interactions, while philosophy for reflects on conceptual norms, sociality, human capacities, social roles as well as legal and ethical responsibilities, and philosophy by expresses any fundamental re-orientation of philosophical research that might occur due to its activities (Seibt, 2018).

The tentative definition of robopsychology that we would like to offer is similar: the psychology of, for, and by robots, robotics, and artificial intelligence (AI). This wording contains a broader scope than social robots only. Additionally, robots and robotics expresses the fact that both the actual products as well as the ongoing process of designing and building robots are worthy topics for psychological research. We also propose to add AI so that the sub-discipline is not only limited to physical manifestations but also considers latent processes related to this technology. In this definition, the psychology of robots, robotics, and AI addresses psychological implications of encountering robots and AI as well as people’s views regarding this technology. Psychology for concerns areas that are relevant in the design of robots and AI and the facilitation of the robotic applications in society. Lastly, psychology by acknowledges any fundamental changes in the way in which psychological topics in the study of robots and AI may be approached in the future. The latter can include issues such as transhumanism (DeFalco, 2020) and expresses the potential for AI to eventually even participate in the discipline of psychology.

Conclusion: The need for a science of robopsychology

With the predicted arrival of the so-called Fourth Industrial Revolution characterized by transformation through robotics and automation (Karabegović et al., 2020), psychological research can be expected to experience transformational changes. A rapidly expanding scope of application of robotic technology is already noticeable as robotics has moved from primarily industrial uses to areas involving direct contact with people, such as robots in the service industry, in educational settings, and as social agents. As our review illustrated, there is currently no psychological sub-discipline dedicated to the study of the effects that robots have on people’s lives, which is currently only addressed through interdisciplinary fields such as human-robot interaction or social robotics. The advantages of organizing psychological research through the formation of special interest groups and sub-disciplines is undoubtedly the driver of the richness and diversity demonstrated in Table 1 of our review. With this review, we encourage activities toward the recognition of robopsychology as the sub-discipline that enables the necessary academic and theoretical infrastructure to facilitate psychological investigations in this changing world. Such work requires specific psychological theories and models to describe the increasing complexities of human interactions with robots, such as intimacy and spirituality, as well as suitable research methods and measurement of psychological constructs that meet quality standards for psychological research (Krägeloh et al., 2019). Our proposed definition of robopsychology is intentionally broad to permit a range of future applications and may be considered parallel to the already existing sub-discipline of robophilosophy. To what extent there is eventual demand for the sub-discipline of robopsychology is up for the future to decide. With this article, we hope to instigate the necessary debates.

Author contributions

JB conceived of the idea of proposing the field of robopsychology, which was subsequently discussed by all authors. CK created the proposed definition for the field of robopsychology, conducted the review, and provided the first draft. All authors contributed to the article and approved the submitted version.

Conflict of interest

JA-C was employed by the company Lighthouse Disruptive Innovation Group, LLC.

The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

American Psychological Association (APA) (2022a). APA Division. Available at: https://www.apa.org/about/division (Accessed June 6, 2022).

Google Scholar

American Psychological Association (APA) (2022b). Applied Experimental and Engineering Psychology. Available at: https://www.apa.org/about/division/div21 (Accessed June 6, 2022).

Google Scholar

Association for Computing Machinery (2022). ACM Transactions on Human-Robot Interaction. Available at: https://dl.acm.org/journal/thri (Accessed June 6, 2022).

Google Scholar

Bartneck, C., Yogeeswaran, K., Ser, Q. M., Woodward, G., Sparrow, R., Wang, S., and Eyssel, F. (2018). “Robots and racism,” in Proceedings of the 2018 ACM/IEEE international conference on human-robot interaction, 196–204.

Google Scholar

Bátfai, N. (2020). Hacking with God: a common programming language of robopsychology and robophilosophy. arXiv preprint arXiv:2009.09068. doi: 10.48550/arXiv.2009.09068

CrossRef Full Text | Google Scholar

Belpaeme, T., Kennedy, J., Ramachandran, A., Scassellati, B., and Tanaka, F. (2018). Social robots for education: a review. Sci. Robot. 3:aat5954. doi: 10.1126/scirobotics.aat5954

CrossRef Full Text | Google Scholar

Čapek, K. (2004). R.U.R (Rossum’s Universal Robots). London: Penguin.

Google Scholar

Cave, S., and Dihal, K. (2018). Ancient dreams of intelligent machines: 3,000 years of robots. Nature 559, 473–475. doi: 10.1038/d41586-018-05773-y

CrossRef Full Text | Google Scholar

Costescu, C. A., Vanderborght, B., and David, D. O. (2014). The effects of robot-enhanced psychotherapy: a meta-analysis. Rev. Gen. Psychol. 18, 127–136. doi: 10.1037/gpr0000007

CrossRef Full Text | Google Scholar

DeFalco, A. (2020). Towards a theory of posthuman care: real humans and caring robots. Body Soc. 26, 31–60. doi: 10.1177/1357034X20917450

CrossRef Full Text | Google Scholar

Dong, J., Lawson, E., Olsen, J., and Jeon, M. (2021). Female voice agents in fully autonomous vehicles are not only more likeable and comfortable, but also more competent. Proc. Hum. Factors Ergon. Soc. 64, 1033–1037. doi: 10.1177/1071181320641248

CrossRef Full Text | Google Scholar

Döring, N., Mohseni, M. R., and Walter, R. (2020). Design, use, and effects of sex dolls and sex robots: scoping review. J. Med. Internet Res. 22:e18551. doi: 10.2196/18551

PubMed Abstract | CrossRef Full Text | Google Scholar

Duradoni, M., Colombini, G., Russo, P. A., and Guazzini, A. (2021). Robotic psychology: a PRISMA systematic review on social-robot-based interventions in psychological domains. Journals 4, 664–709. doi: 10.3390/j4040048

CrossRef Full Text | Google Scholar

Edwards, C., Edwards, A., Stoll, B., Lin, X., and Massey, N. (2019). Evaluations of an artificial intelligence instructor’s voice: social identity theory in human-robot interactions. Comput. Hum. Behav. 90, 357–362. doi: 10.1016/j.chb.2018.08.027

CrossRef Full Text | Google Scholar

Frontiers in Psychology (2022). Frontiers in Psychology - Sections. Available at: https://www.frontiersin.org/journals/psychology (Accessed June 6, 2022).

Google Scholar

Fuentes-Moraleda, L., Díaz-Pérez, P., Orea-Giner, A., Muñoz-Mazónc, A., and Villacé-Molinero, T. (2020). Interaction between hotel service robots and humans: a hotel-specific service robot acceptance model (sRAM). Tour. Manag. Perspect. 36:100751. doi: 10.1016/j.tmp.2020.100751

CrossRef Full Text | Google Scholar

Fusté-Forné, F. (2021). Robot chefs in gastronomy tourism: what’s on the menu? Tour. Manag. Perspect. 37:100774. doi: 10.1016/j.tmp.2020.100774

CrossRef Full Text | Google Scholar

Gallagher, S. (2013). You and I, robot. AI & Soc. 28, 455–460. doi: 10.1007/s00146-012-0420-4

CrossRef Full Text | Google Scholar

Gasteiger, N., Loveys, K., Law, M., and Broadbent, E. (2021). Friends from the future: a scoping review of research into robots and computer agents to combat loneliness in older people. Clin. Interv. Aging 16, 941–971. doi: 10.2147/CIA.S282709

PubMed Abstract | CrossRef Full Text | Google Scholar

Grant, M. J., and Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Info. Libr. J. 26, 91–108. doi: 10.1111/j.1471-1842.2009.00848.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Karabegović, I. (2016). The role of industrial robots in the development of automotive industry in China. Int. J. Eng. Works 3, 92–97.

Google Scholar

Karabegović, I., Turmanidze, R., and Dašić, P. (2020). “Robotics and automation as a foundation of the fourth industrial revolution-industry 4.0,” in Advanced Manufacturing Processes. Inter Partner 2019. Lecture Notes in Mechanical Engineering. eds. V. Tonkonogyi, V. Ivanov, J. Trojanowska, G. Oborskyi, M. Edl, and I. Kuric, (Cham: Springer).

Google Scholar

Konolige, K. G. (1985). Experimental Robot Psychology. Washington, DC: SRI International.

Google Scholar

Krägeloh, C. U., Bharatharaj, J., Kutty, S. K. S., Nirmala, P. R., and Huang, L. (2019). Questionnaires to measure acceptability of social robots: a critical review. Robotics 8:88. doi: 10.3390/robotics8040088

CrossRef Full Text | Google Scholar

Lane, T. (2018). A short history of robotic surgery. Ann. R. Coll. Surg. Engl. 100, 5–7. doi: 10.1308/rcsann.supp1.5

PubMed Abstract | CrossRef Full Text | Google Scholar

Libin, A. V., and Libin, E. V. (2004). Person-robot interactions from the robopsychologists’ point of view: the robotic psychology and robotherapy approach. Proc. IEEE 92, 1789–1803. doi: 10.1109/JPROC.2004.835366

CrossRef Full Text | Google Scholar

Linz Institute of Technology (2022). Robosychology Lab am Linz Institute of Technology. Available at: https://www.jku.at/lit-robopsychology-lab (Accessed June 6, 2022).

Google Scholar

Mara, M., Appel, M., and Gnambs, T. (2022). Human-like robots and the uncanny valley: a meta-analysis of user responses based on the Godspeed scales. Z. Psychol. 230, 33–46. doi: 10.1027/2151-2604/a000486

CrossRef Full Text | Google Scholar

Mayor, A. (2018). Gods and robots – myths, machines, and ancient dreams of technology. Princeton, NJ: Princeton University Press.

Google Scholar

Melson, G. F., Kahn, P. H., Beck, A., and Friedman, B. (2009). Robotic pets in human lives: implications for the human–animal bond and for human relationships with personified technologies. J. Soc. Issues 65, 545–567. doi: 10.1111/j.1540-4560.2009.01613.x

CrossRef Full Text | Google Scholar

Mubin, O., Wadibhasme, K., Jordan, P., and Obaid, M. (2019). Reflecting on the presence of science fiction robots in computing literature. ACM Trans. Hum.-Robot Interact. 8, 1–25. doi: 10.1145/3303706

CrossRef Full Text | Google Scholar

Nitsch, V., and Popp, M. (2014). Emotions in robot psychology. Biol. Cybern. 108, 621–629. doi: 10.1007/s00422-014-0594-6

CrossRef Full Text | Google Scholar

Pozharliev, R., De Angelis, M., Rossi, D., Romani, S., Verbeke, W., and Cherubino, P. (2021). Attachment styles moderate customer responses to frontline service robots: evidence from affective, attitudinal, and behavioral measures. Psychol. Mark. 38, 881–895. doi: 10.1002/mar.21475

CrossRef Full Text | Google Scholar

Savela, N., Turja, T., Latikka, R., and Oksanen, A. (2021). Media effects on the perceptions of robots. Hum. Behav. Emerg. Technol. 3, 989–1003. doi: 10.1002/hbe2.296

CrossRef Full Text | Google Scholar

Seibt, J. (2018). “Robophilosophy,” in Posthuman Glossary. eds. R. Braidotti and M. Hlavajova (London: Bloomsbury), 390–393.

Google Scholar

Servick, K. (2019). Could robots be psychology’s new lab rats? Science. doi: 10.1126/science.aaz7641

CrossRef Full Text | Google Scholar

Siciliano, B., and Khatib, O. (2016). Springer Handbook of Robotics. New York: Springer.

Google Scholar

Springer (2022a). Intelligent Service Robotics. Available at: https://springer.com/journal/11370 (Accessed June 6, 2022).

Google Scholar

Springer (2022b). International Journal of Social Robotics. Available at: https://springer.com/journal/12369 (Accessed June 6, 2022).

Google Scholar

Trovato, G., De Saint Chamas, L., Nishimura, M., Paredes, R., Lucho, C., Huerta-Mercado, A., et al. (2021). Religion and robots: towards the synthesis of two extremes. Int. J. Soc. Robot. 13, 539–556. doi: 10.1007/s12369-019-00553-8

CrossRef Full Text | Google Scholar

Tzafestas, S. G. (2016). An Introduction to Robophilosophy: Cognition, Intelligence, Autonomy, Consciousness, Conscience and Ethics. Sterling, VA: Stylus Publishing.

Google Scholar

Viik, T. (2020). Falling in love with robots: a phenomenological study of experiencing technological alterities. Paladyn, J. Behav. Robot. 11, 52–65. doi: 10.1515/pjbr-2020-0005

CrossRef Full Text | Google Scholar

Watson, D. P., Adams, E. L., Shue, S., Coates, H., McGuire, A., Chesher, J., et al. (2018). Defining the external implementation context: an integrative systematic literature review. BMC Health Serv. Res. 18:209. doi: 10.1186/s12913-018-3046-5

PubMed Abstract | CrossRef Full Text | Google Scholar

Zinina, A., Zaidelman, L., Arinkin, N., and Kotov, A. (2020). Non-verbal behavior of the robot companion: a contribution to the likeability. Procedia Comput. Sci. 169, 800–806. doi: 10.1016/j.procs.2020.02.160

CrossRef Full Text | Google Scholar

Keywords: psychology, sub-discipline, special interest group, robot psychology, robotic psychology, robopsychology, robots, artificial intelligence

Citation: Krägeloh CU, Bharatharaj J, Albo-Canals J, Hannon D and Heerink M (2022) The time is ripe for robopsychology. Front. Psychol. 13:968382. doi: 10.3389/fpsyg.2022.968382

Received: 13 June 2022; Accepted: 29 August 2022;
Published: 22 September 2022.

Edited by:

Luca Tummolini, National Research Council (CNR), Italy

Reviewed by:

Michał Klincewicz, Tilburg University, Netherlands
Rudolf M. Oosthuizen, University of South Africa, South Africa

Copyright © 2022 Krägeloh, Bharatharaj, Albo-Canals, Hannon and Heerink. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Christian U. Krägeloh, Y2hyaXMua3JhZ2Vsb2hAYXV0LmFjLm56

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.