This commentary argues that while using popular franchises like Harry Potter can be a helpful tool to make research on personality and career choices salient and engaging to various audiences, results should not be overgeneralised. In particular, we argue that (1) conclusions should not be drawn uncritically from statistically significant relations, (2) capturing personality requires validated assessments and should not be reduced to a single item, and (3) in the specific case of the Harry Potter franchise, the mere preference for a House of the fictional Hogwarts School of Witchcraft and Wizardry rarely predicts meaningful aspects of personality traits. As such, caution is advised when such fictional elements are used, as they can quickly go viral and may provide potentially harmful advise if shared uncritically.

In their recently published paper entitled The Sorting Hat of Medicine: Why Hufflepuffs Wear Stethoscopes and Slytherins Carry Scalpels,Baimas-George & Vrochides (2020) investigate whether self-identification with a Hogwarts house from the fictional world of Harry Potter is related to physicians’ choices of speciality. The authors found substantive differences in Hogwarts house preferences between people working in different medical specialities and associated such differences to personality traits. As magical as this may sound at the first read, the results are not entirely surprising: different medical specializations attract different kinds of people, and Hogwarts houses were intended to depict distinctive types of students. After all, many readers may have found themselves wondering which house the magical Sorting Hat would have put them into: Am I brave enough to consider myself a Gryffindor? Am I so agreeable that I would rather be considered a Hufflepuff? Likewise, medical students may ask themselves: am I ambitious enough to be a surgeon, or am I agreeable enough to dedicate myself to paediatrics?

Using the popular Harry Potter franchise to investigate important topics such as how to choose a fulfilling career can be a helpful tool to make the research salient and engaging for medical students and other audiences. The exploration of unique personality traits among members of certain groups, such as the medical profession, is an interesting pursuit with a long history in psychology and psychometrics. In this sense, the authors reflect that “[t]his information [ratios of residents per Hogwarts house] may guide prospective residents in formulating an understanding of career desires from comprehension of their own personalities” (Baimas-George & Vrochides, 2020, p. 2). Unfortunately, while having identification with a Hogwarts house as a reliable proxy for someone's personality would be exciting, we are in danger of fooling ourselves through a confirmation bias.

As we have shown in our own research (Jakob et al., 2019), even though the connection between identification with a Hogwarts house and personality might seem self-evident (Crysel et al., 2015), there is little empirical evidence to support it uncritically. In this sense, we do not seek to criticize Baimas-George and Vrochides’ approach of utilising a predictor rooted in pop culture, but to highlight that the connection between Hogwarts house choice and personality traits is not as straightforward as it may appear. Self-reported preference for a Hogwarts house rarely predicts meaningful aspects of personality traits (or Basic Human Values), at least when measured based on contemporary validated psychological theories (Jakob et al., 2019). In other words, even though deciding on a medical speciality might be guided by individual personality traits to some extent, the preference for a specific Hogwarts house does not reveal somebody’s personality traits as if by magic (Jakob et al., 2019). Capturing personality is a much more complicated matter that requires validated, dedicated assessments. In this sense, psychologists continue debating the most appropriate way to understand and assess complex individual characteristics such as one’s personality (Christensen et al., 2019). Reducing this endeavour to one variable, such as somebody's Hogwarts house preference—especially when advising on important life choices—seems questionable. Unlike, for example, the Sorting Hat Quiz—developed by the author of the Harry Potter book series—which allows for some variability and includes questions on preferences and behaviour, a single item such as Hogwarts house preference actually tells us little—if anything—about a person. We do not know how stable preferences are over time, how accurately house descriptions are remembered or interpreted, or how different levels of engagement with the franchise may affect house preference. To cut it short: we have no information on the reliability or validity of this item.

Further, there is no evidence on whether a decision informed by a Hogwarts house preference is actually a desirable path to follow. The goal of any assessment tool in a vocational context is to provide individuals with the best fit for them to advance in their professional careers and to personally thrive while doing so. These tools are often developed by capturing skills, personality, or other traits and states of people working in the field. Baimas-George and Vrochides suggest that the use of a single, largely unexplored item could be a reliable variable that shows the fit of a physician’s personality to their choice of specialty. We challenge such a claim, particularly when no evidence is provided regarding any life outcomes: Are those whose house preference match specialty happier, more satisfied, more competent in their jobs? This lack of validity compromises not only the results presented in the original article but also its use for any substantial individual decision. In other words, whether using a single item reflecting a preference for a fictional world element could be useful for this end is still unclear and warrants concerns about the future and appropriateness of such endeavours.

The franchise is incredibly popular and it is therefore unsurprising that the publication gathered enthusiastic praise across social media (i.e., with more than 1,100 tweets related to this article as of July 2020). While we welcome the energizing and positive responses to this study of personality and career path choice, we also believe that the attention the study received stresses the necessity of exercising caution to avoid any misconceptions and overgeneralizations. Beyond our major concerns previously addressed, there exist a number of methodological issues that might have further jeopardized Baimas-George and Vrochides’ (2020) results: presenting underpowered comparisons performed using data subsets including a limited number of individuals or the lack of multiple comparisons correction in their analyses, among others. Additionally, we believe that readers would have benefited from the authors focusing on studying effect sizes instead of pure statistical significance testing (see Funder & Ozer, 2019), particularly when presenting results to the public in sections such as the abstract. Furthermore, we find the causal language used in the original text to be unwarranted, and the interpretation of the results problematic. Additionally, the potential effect of self-selection and individual familiarity with the Harry Potter franchise was left undiscussed in the results. In this sense, we would like to stress that the implication of causality in the title is vastly misleading. Not only is the methodology not adequate to infer causality (and a randomised controlled trial would have indeed been somewhat excessive and unethical in this case), but the authors do not actually answer the question of why Hufflepuffs wear stethoscopes and Slytherins carry scalpels.

This brief commentary is intended for researchers and medical professionals to be wary of recommending using Harry Potter and other fictional works when guiding medical students in approaching their future career options. We believe that more extensive, in-depth research would be required to draw such strong conclusions. We ultimately agree with the authors that important lifetime decisions (such as deciding for a medical specialty) will reflect, to some extent, individuals’ personality. Overall, we concur that if surgeons are depicted to have certain individual features (i.e., to be powerful, astute), people with similar personality traits (i.e., such as high self-esteem or higher authoritarianism) will be more likely to choose that career path. What we put into question is the adequacy of assessing such personality traits utilizing these fictional elements. Even though it would be thrilling if personality could be revealed to us with a movement of a magic wand or by casting a spell, unfortunately, it is a much more complicated task. Our position here is clear: evidence shows that personality is not, to a reliable extent, measured by someone’s preference for a Hogwarts house. Thus, using the latter to guide one's career options seems overly enthusiastic and potentially harmful, if left unquestioned. We scrutinised similar research endeavours before, and we do it here again - even at the expense of feeling that we might spoil the magic by revealing the underlying trick.

Competing interests

The authors have no competing interests to disclose.

References

References
Baimas-George, M., & Vrochides, D. (2020). The Sorting Hat of Medicine: Why Hufflepuffs Wear Stethoscopes and Slytherins Carry Scalpels. Journal of Surgical Education, 77(4), 772–778. https://doi.org/10.1016/j.jsurg.2020.01.004
Christensen, A. P., Golino, H., & Silvia, P. J. (2019). A Psychometric Network Perspective on the Validity and Validation of Personality Trait Questionnaires. https://doi.org/10.31234/osf.io/ktejp
Crysel, L. C., Cook, C. L., Schember, T. O., & Webster, G. D. (2015). Harry Potter and the measures of personality: Extraverted Gryffindors, agreeable Hufflepuffs, clever Ravenclaws, and manipulative Slytherins. Personality and Individual Differences, 83, 174–179. https://doi.org/10.1016/j.paid.2015.04.016
Funder, D. C., & Ozer, D. J. (2019). Evaluating effect size in psychological research: Sense and nonsense. Advances in Methods and Practices in Psychological Science, 2(2), 156–168. https://doi.org/10.1177/2515245919847202
Jakob, L., Garcia-Garzon, E., Jarke, H., & Dablander, F. (2019). The Science Behind the Magic? The Relation of the Harry Potter “Sorting  Hat Quiz” to Personality and Human Values. Collabra: Psychology, 5(1), 31. https://doi.org/10.1525/collabra.240