Diederik Alexander Stapel (born 19 October 1966) is a Dutch former professor of social psychology at Tilburg University. In 2011 Tilburg University suspended Stapel for fabricating and manipulating data for his research publications. This scientific misconduct took place over a number of years and affected dozens of his publications. As of 2019[update], Stapel has had 58 of these publications retracted and is by some regarded as "the biggest con man in academic science".
In high school, he met his would-be wife Marcelle, whom he later married in 1997. After completing his schooling, Stapel, for a while, studied acting at East Stroudsburg University in Pennsylvania before moving back to the Netherlands for an undergraduate degree in Psychology.
Stapel obtained an M.A. in psychology and communications in 1991 and a PhD cum laude in social psychology in 1997, all from the University of Amsterdam. He became a professor at the University of Groningen in 2000 and moved to Tilburg University in 2006, where he founded TiBER, the Tilburg Institute for Behavioral Economics Research. In September 2010, Stapel became dean of the social and behavioral sciences faculty.
Stapel received the Career Trajectory Award from the Society of Experimental Social Psychology in 2009, which has since been retracted. He returned his PhD title to the University of Amsterdam in November 2011, noting that his "behavior of the past years are inconsistent with the duties associated with the doctorate".
In October 2014, Dutch media reporter, Eli MacColl, stated that Stapel had returned to work, teaching social philosophy at the Fontys Academy for Creative Industries in Tilburg.
On 31 October 2011, a committee entrusted with investigating "the extent and nature of the breach of scientific integrity committed by Mr D.A. Stapel", formed by the Rector Magnificus of Tilburg University and chaired by Willem ("Pim") Levelt, published an interim report regarding Stapel's activities at the three Dutch universities where he had worked. The interim report pointed to three unidentified young researchers as the whistleblowers for the case, and implies that these whistleblowers spent months making observations of Stapel and his work before they concluded that something actually was wrong.
The report also cites two professors who claim they had previously seen examples of Stapel's data that were "too good to be true." The report concluded that Stapel made up data for at least 30 publications.
His general method towards the end of his career was to develop a complete experiment at the level of theory, hypotheses, methods, stimuli, questionnaires, and even participants' rewards – and then pretend that he would run the experiments at schools to which only he had access. Instead of doing so, he would make up the data and send these to colleagues for further analysis. The report also stated that earlier in his career, going back at least to 2004, he appears to have manipulated data rather than faked them.
In all cases he acted alone and the report did not find any indication that coauthors, PhD students, or others were aware even in instances where suspicion may have been reasonable. On pages six to seven, the interim report names 19 theses prepared with data delivered by Stapel. Of those, seven have been cleared. There are various degrees of suspicion about the remaining 12. The report advised that the degrees of the students involved should not be retracted.
It became widely known that Stapel treated his graduate students unfairly, with most of them graduating without ever actually completing an experiment. Stapel controlled the data in his lab, and when students asked to see the raw data, they were often given excuses.
According to the report, there were occasions when Stapel's data were given to an assistant to be entered into a computer. This assistant would then return the data file to Stapel. The researcher analyzing the data would then receive the file directly from Stapel. Stapel would apparently tell this researcher to "Be aware that you have gold in your hands." The report also suggests that Stapel elected to present a list of publications that contained fictitious data.
The interim report stated that it was not possible to determine whether Stapel fabricated or manipulated data for his 1997 dissertation at the University of Amsterdam, because the data had been destroyed. The university announced that it would investigate whether it would be possible to retract Stapel's PhD because of exceptionally unworthy scientific behavior.
The interim report stated that Stapel had caused severe damage to young people at the beginning of their careers, as well as to the general confidence in science, in particular social psychology. The University of Tilburg announced that it would pursue criminal prosecution of Stapel.
An extensive report investigates all of Stapel's 130 articles and 24 book chapters. A website was set up on 27 March 2012 to publish intermediate findings. According to the first findings, on the first batch of 20 publications by Stapel, studied by the Levelt committee, 12 were falsified and three contributions to books were also fraudulent. de Volkskrant reported that the final report was due on 28 November 2012, and that a book by Stapel was to be released around the same time.
"We have some 30 papers in peer-reviewed journals where we are actually sure that they are fake, and there are more to come," Pim Levelt, chair of the committee investigating Stapel's work stated.[incomplete short citation]
Coping with chaos
A month after Tilburg University announced that it had found evidence of fraud in Stapel's work, the journal Science posted a retraction notice on Stapel's co-authored paper entitled Coping with chaos: How disordered contexts promote stereotyping and discrimination. The report from Science says:
Our Report "Coping with chaos: How disordered contexts promote stereotyping and discrimination" reported the effects of the physical environment on human stereotyping and discriminatory behavior. On 31 October 2011, the University of Tilburg held a press conference to announce findings of their investigation into possible data fraud on the part of author Stapel. These findings of the university's interim report included fabrication of data in this Science paper. Therefore, we are retracting the paper, with apologies from author Stapel. Coauthor Lindenberg was in no way involved in the generation of the data, and agrees to the retraction of the paper.
In December 2011, Stapel retracted this paper, the first to be retracted. The journal expressed initial concern regarding the paper's validity on 1 November. In a response to the retraction, coauthor of the Chaos paper Siegwart Lindenberg told the journal in an email, "Stapel's doing had caught me as much by surprise as it did anybody else. I never had any suspicion. He was a very trusted man, dean of the faculty, brilliant, successful, no indications for me to be distrustful. In this, I was not the only one. I also had no trouble with the results of the experiments."
Selfishness in carnivores
The research result, obtained by Stapel and co-workers Roos Vonk and Marcel Zeelenberg, that carnivores are more selfish than vegetarians, which was widely publicized in Dutch media, was suspected and later turned out to be based on falsified data. The research result had not yet been published in a scientific journal; only a press bulletin was released.
Reaction by Stapel
Responding to the interim report, Stapel stated:
I failed as a scientist. I adapted research data and fabricated research. Not once, but several times, not for a short period, but over a longer period of time. I realize that I shocked and angered my colleagues, because of my behavior. I put my field, social psychology in a bad light. I am ashamed of it and I deeply regret it ... I think it is important to emphasize that I never informed my colleagues of my inappropriate behavior. I offer my colleagues, my PhD students, and the complete academic community my sincere apologies. I am aware of the suffering and sorrow that I caused to them ... I did not withstand the pressure to score, to publish, the pressure to get better in time. I wanted too much, too fast. In a system where there are few checks and balances, where people work alone, I took the wrong turn. I want to emphasize that the mistakes that I made were not born out of selfish ends.
In his memoirs published in November 2012, Stapel admits his fraud, but protests against the accusation in the interim report that he was a cunning, manipulative fraud with a plan.
Reaction in academia
On 28 November 2012, the joint final report, from the three investigating committees, was published.
It has been suggested that Stapel was able to continue his fraud for so long because of his status. At Tilburg he was "considered a star"[This quote needs a citation] and was seen by his colleagues and students as charismatic, friendly and incredibly talented. Many students became his personal friends. But the final Levelt report raises more controversial questions about the ways in which Stapel went unchallenged for so long. The report concludes that there was "a more general failure of scientific criticism in the peer community and a research culture that was excessively oriented to uncritical confirmation of one's own ideas and to finding appealing but theoretically superficial ad hoc results". It goes on to suggest that "not infrequently reviews [of social psychology journal articles] were strongly in favour of telling an interesting, elegant, concise and compelling story, possibly at the expense of the necessary scientific diligence."
This aspect of the report has been criticised by the Social Psychology Section of the British Psychological Society. In a letter to the Times Higher Education Supplement, on behalf of the Section, Stephen Gibson at York St John University, points out ".. there are no grounds for concluding either that research fraud is any more common in social psychology than other disciplines or that its editorial processes are particularly poor at detecting it,"[This quote needs a citation] adding that: "Our sub-discipline does not deserve the harm to its reputation that may be provoked by the careless implication of unique deficiencies."[This quote needs a citation] The Levelt report has also been criticised by the European Association of Social Psychology in an open letter to its members.
In the February 2013 issue of The Psychologist, Willem Levelt, together with the chairs of the other two investigating committees, published a rejoinder to these and other criticisms. Drenth et al. acknowledge that they did not compare the situation in social psychology with other disciplines, but note that "such a comparative investigation was not part of the Committees' commission."[This quote needs a citation]
In a review for the Association for Psychological Science, Stapel's 315-page memoirs, entitled Ontsporing ("Derailed"), is described by Dutch psychologists Denny Borsboom and Eric-Jan Wagenmakers as "priceless and revealing." Stapel recounts that his misdemeanours began when he was sitting alone in his office and changed "an unexpected 2 into a 4". The reviewers describe the final chapter of the book as "unexpectedly beautiful" but note that it is full of lines taken from the works of writers Raymond Carver and James Joyce.
In June 2013 Stapel agreed, in a settlement with the prosecutor, to perform 120 hours of community service and to lose the right to some benefits associated with his former job equivalent to a year and a half's worth of salary. In this way, he avoided further criminal prosecution.
List of withdrawn publications
- Maringer, Marcus; Stapel, Diederik (2009). "Correction or comparison? The effects of prime awareness on social judgments". European Journal of Social Psychology. 39 (5): 719–733. doi:10.1002/ejsp.569.
- Ruys, Kirsten; Stapel, Diederik; Aarts, Henk (21 September 2010). "From (Unconscious) Perception to Emotion: A Global-to-Specific Unfolding View of Emotional Responding" (Chapter 4 of "Emotion Regulation and Well-Being"). Springer. ISBN 978-1-4419-6952-1. Retrieved 22 March 2017.
- Komen, Willem; Stapel, Diederik (November 1998). "Interpretation versus Reference Framing: Assimilation and Contrast Effects in the Organizational Domain". Organizational Behavior and Human Decision Processes. 76 (2): 132–148. doi:10.1006/obhd.1998.2802. PMID 9831519.
- Schwinghammer, Saskia; Stapel, Diederik (December 2006). "The Effects of Different Types of Self–Activation on Social Comparison Orientation". Social Cognition. 24 (6): 703–722. doi:10.1521/soco.2006.24.6.703.
|Title||Year of publication||Journal||DOI and link to the retraction notice|
|Interpretation versus Reference Framing: Assimilation and Contrast Effects in the Organizational Domain||1998||Organizational Behavior and Human Decision Processes||10.1016/j.obhdp.2015.11.002|
|Correction or comparison? The effects of prime awareness on social judgments||2009||European Journal of Social Psychology||10.1002/ejsp.2173|
|The impact of comprehension versus self-enhancement goals on group perception||2008||Social Psychology||10.1027/1864-9335/a000152|
|Measure by measure: When implicit and explicit social comparison effects differ||2010||Self and Identity||10.1080/15298868.2013.790597|
|Unfinished business: How completeness affects the impact of emotional states and emotion concepts on social judgement||2006||Journal of Experimental Social Psychology||10.1016/j.jesp.2013.03.006|
|Hardly thinking about close and distant others: On cognitive business and target closeness in social comparison effects||2005||Journal of Experimental Social Psychology||10.1016/j.jesp.2013.03.005|
|The flexible unconscious: Investigating the judgmental impact of varieties of unaware perception||2005||Journal of Experimental Social Psychology||10.1016/j.jesp.2013.03.004|
|Distinctiveness is Key: How Different Types of Self-Other Similarity Moderate Social Comparison Effects||2007||Personality & Social Psychology Bulletin||10.1177/0146167212474240|
|Terror Management and Stereotyping: Why Do People Stereotype When Mortality Is Salient?||2008||Personality & Social Psychology Bulletin||10.1177/0146167212474240|
|When we wonder what it all means: Interpretation goals facilitate accessibility and stereotyping effects||2001||Personality & Social Psychology Bulletin||10.1177/0146167212474240|
|The effects of diffuse and distinct affect||2002||Journal of Personality and Social Psychology||10.1037/a0031698|
|Me tomorrow, the others later: How perspective fit increases sustainable behavior||2010||Journal of Environmental Psychology||10.1016/j.jenvp.2012.12.004|
|Similarities and Differences between the Impact of Traits and Expectancies: What Matters Is Whether the Target Stimulus Is Ambiguous or Mixed||2002||Journal of Experimental Social Psychology||10.1016/j.jesp.2012.12.001|
|Information to go: Fluency enhances the usability of primed information||2009||Journal of Experimental Social Psychology||10.1016/j.jesp.2012.11.014|
|Distinguishing stereotype threat from priming effects: on the role of the social self and threat-based concerns||2006||Journal of Personality and Social Psychology||10.1037/a0031270|
|From seeing to being: subliminal social comparisons affect implicit and explicit self-evaluations||2004||Journal of Personality and Social Psychology||10.1037/a0031410|
|Method matters: effects of explicit versus implicit social comparisons on activation, behavior, and self-views||2004||Journal of Personality and Social Psychology||10.1037/a0031425|
|The magic spell of language: linguistic categories and their perceptual consequences||2007||Journal of Personality and Social Psychology||10.1037/a0031271|
|The self salience model of other-to-self effects: integrating principles of self-enhancement, complementarity, and imitation||2006||Journal of Personality and Social Psychology||10.1037/a0031426|
|Unconscious and spontaneous and...complex: the three selves model of social comparison assimilation and contrast||2008||Journal of Personality and Social Psychology||10.1037/a0031266|
|The Norm-Activating Power of Celebrity: The Dynamics of Success and Influence||2011||Social Psychology Quarterly||10.1177/0190272512471170|
|The downside of feeling better: Self-regard repair harms performance||2008||Self and Identity||10.1080/15298868.2012.742330|
|Status concerns and financial debts in adolescents||2010||Social Influence||10.1080/15534510.2012.738953|
|It's all in the timing: Measuring emotional reactions to stereotype threat before and after taking a test||2006||European Journal of Social Psychology||10.1002/ejsp.1919|
|Making sense of war: using the interpretation comparison model to understand the Iraq conflict||2006||European Journal of Social Psychology||10.1002/ejsp.1920|
|Staff, miter, book, share: how attributes of Saint Nicholas induce normative behavior||2008||European Journal of Social Psychology||10.1002/ejsp.1913|
|Affects of the unexpected: when inconsistency feels good (or bad)||2010||Personality & Social Psychology Bulletin||10.1177/0146167212462821|
|Event Accessibility and Context Effects in Causal Inference: Judgment of a Different Order||1996||Personality & Social Psychology Bulletin||10.1177/0146167212462821|
|Silence and Table Manners: When Environments Activate Norms||2008||Personality & Social Psychology Bulletin||10.1177/0146167212462821|
|The influence of mood on attribution||2010||Personality & Social Psychology Bulletin||10.1177/0146167212462821|
|Why people stereotype affects how they stereotype: the differential influence of comprehension goals and self-enhancement goals on stereotyping||2009||Personality & Social Psychology Bulletin||10.1177/0146167212462821|
|Stop Making Sense: The Ultimate Fear||2009||Psychological Inquiry||10.1080/1047840X.2012.722053|
|Behavioural effects of automatic interpersonal versus intergroup social comparison||2006||British Journal of Social Psychology||10.1348/014466605X79589|
|How to heat up from the cold: examining the preconditions for (unconscious) mood effects||2008||Journal of Personality and Social Psychology||10.1037/a0029740|
|Mood and context-dependence: Positive mood increases and negative mood decreases the effects of context on perception||2010||Journal of Personality and Social Psychology||10.1037/a0029743|
|Moods as spotlights: the influence of mood on accessibility effects||2008||Journal of Personality and Social Psychology||10.1037/a0029742|
|No pain, no gain: the conditions under which upward comparisons lead to better performance||2007||Journal of Personality and Social Psychology||10.1037/a0029731|
|On models and vases: body dissatisfaction and proneness to social comparison effects||2007||Journal of Personality and Social Psychology||10.1037/a0029732|
|The referents of trait inferences: The impact of trait concepts versus actor–trait links on subsequent judgments||1996||Journal of Personality and Social Psychology||10.1037/a0029744|
|What drives self-affirmation effects? On the importance of differentiating value affirmation and attribute affirmation||2011||Journal of Personality and Social Psychology||10.1037/a0029745|
|Beauty as a tool: The effect of model attractiveness, product relevance, and elaboration likelihood on advertising effectiveness||2010||Psychology & Marketing||10.1002/mar.20565|
|When different is better: Performance following upward comparison||2006||European Journal of Social Psychology||10.1002/ejsp.1903|
|The unconscious unfolding of emotions||2009||European Review of Social Psychology||10.1080/10463283.2012.705989|
|Emotion elicitor or emotion messenger? Subliminal priming reveals two faces of facial expressions||2008||Psychological Science||10.1177/0956797612453137|
|Judging the unexpected: Disconfirmation of situation-specific expectancies||2009||European Journal of Social Psychology||10.1002/ejsp.1898|
|Racist biases in legal decisions are reduced by a justice focus||2010||European Journal of Social Psychology||10.1002/ejsp.1897|
|The secret life of emotions||2008||Psychological Science||10.1177/0956797612453137|
|When nothing compares to me: How defensive motivations and similarity shape social comparison effects||2006||European Journal of Social Psychology||10.1002/ejsp.1899|
|The Self-Activation Effect of Advertisements: Ads Can Affect Whether and How Consumers Think about the Self||2010||Journal of Consumer Research||10.1086/667237|
|It depends on how you look at it: being versus becoming mindsets determine responses to social comparisons||2010||British Journal of Social Psychology||10.1111/j.2044-8309.2012.02111.x|
|The Effects of Different Types of Self–Activation on Social Comparison Orientation||2006||Social Cognition||10.1521/soco.2006.24.6.703|
|The Mental Roots of System Justification: System Threat, Need for Structure, and Stereotyping||2011||Social Cognition||10.1521/soco.2012.30.3.363|
|When failure feels better than success: Self-salience, self-consistency, and affect||2011||British Journal of Social Psychology||10.1111/j.2044-8309.2012.02108.x|
|Stereotype Disconfirmation Affect: When Sweet Hooligans Make You Happy and Honest Salesmen Make You Sad||2011||Basic and Applied Social Psychology||10.1080/01973533.2012.682012|
|What's in a Name? 361.708 Euros: The Effects of Marital Name Change||2010||Basic and Applied Social Psychology||10.1080/01973533.2012.682012|
|Happiness as alchemy: Positive mood leads to self-serving responses to social comparisons||2011||Motivation and Emotion||10.1007/s11031-011-9266-1|
|Coping with Chaos: How Disordered Contexts Promote Stereotyping and Discrimination||2011||Science||10.1126/science.334.6060.1202-a|
|From (Unconscious) Perception to Emotion: A Global-to-Specific Unfolding View of Emotional Responding||2010||Emotion Regulation and Well-Being||10.1007/978-1-4419-6953-8_20|
Selected scientific publications
- — Koomen, Willem (2001). "I, we, and the effects of others on me: How self-construal moderates social comparison effects". Journal of Personality and Social Psychology. 80 (5): 766–781. doi:10.1037/0022-35220.127.116.116. PMID 11374748.
- — Koomen, Willem (2001). "When we wonder what it all means: Interpretation goals facilitate accessibility and stereotyping effects". Personality and Social Psychology Bulletin. 27 (8): 915–929. doi:10.1177/0146167201278001. S2CID 145617463.
- This paper is one of three retracted by the journal.
- — Tesser, A. (2001). "Self-activation increases social comparison". Journal of Personality and Social Psychology. 81 (4): 742–750. doi:10.1037/0022-3518.104.22.1682. PMID 11642358.
- — Koomen, Willem; Ruijs, K. (2002). "The effects of diffuse and distinct affect". Journal of Personality and Social Psychology. 83 (1): 60–74. doi:10.1037/0022-3522.214.171.124. PMID 12088133.
- — (2003). "Making sense of hot cognition: Why and when description influences our feelings and judgments". In Forgas, J.P; Williams, K.D.; von Hippel, W. (eds.). Social judgments: Implicit and explicit processes. New York, NY, USA: Cambridge. pp. 227–250.
- — Siegwart Lindenberg, S. (8 April 2011). "Coping with Chaos: How Disordered Contexts Promote Stereotyping and Discrimination". Science. 332 (6026): 251–253. Bibcode:2011Sci...332..251S. doi:10.1126/science.1201068. PMID 21474762. S2CID 206531492.
- Stapel, Diederik; Ontsporing ("Derailment"); Prometheus Books, November 2012; ISBN 90-446-2312-5
- A.H.J. Dautzenberg & Diederik Stapel; De fictiefabriek. Een bevrijdingsroman in brieven ("The Fiction Factory. A Liberating Epistolary Novel"); Atlas Contact, September 2014; ISBN 978-90-254-4269-9
- "Diederik Stapel succeeds Theo Verhallen as Dean of the Tilburg School of Social and Behavioral Sciences". Tilburg University. 7 July 2010. Archived from the original on 2 April 2012. Retrieved 17 September 2011.
- "Levelt: fraud detected in 55 publications (2013) | Univers". Universonline.nl. 28 November 2012. Retrieved 1 March 2013.
- "Retraction Watch Database - Stapel". Retraction Watch. Center for Scientific Integrity. Retrieved 22 March 2019.
- "The Mind of a Con Man". 26 April 2013.
- Bhattacharjee, Yudhijith (26 April 2013). "The Mind of a Con Man". The New York Times. Retrieved 15 June 2020.
- Abma, Ruud. "Changes in publication culture and the Stapel fraud case" – via academia.edu. Cite journal requires
- "Diederik Stapel succeeds Theo Verhallen as Dean of the Tilburg School of Social and Behavioral Sciences". Tilburg University. 8 July 2010. Archived from the original on 2 April 2012. Retrieved 5 October 2011.
- "Career Trajectory Award Recipients". Society of Experimental Social Psychology. Retrieved 1 November 2011.
- Redactie. "Stapel doet vrijwillig afstand van doctorstitel – Binnenland – VK". De Volkskrant. Retrieved 17 November 2011.
- "Diederik Stapel doceert bij Fontys". Nederlandse Omroep Stichting (in Dutch). 1 October 2014. Retrieved 2 October 2014.
- "Prof. Diederik Stapel suspended" (Press release). Tilburg University. 7 September 2011. Archived from the original on 2 April 2012. Retrieved 17 September 2011.
- Enserink, Martin (7 September 2011). "Dutch university sacks social psychologist over faked data". Science. Archived from the original on 30 September 2011. Retrieved 17 September 2011.
- "Interim Report Regarding the Breach of Scientific Integrity by Prof. D. A. Stapel" (PDF). Tilburg University. Levelt Committee. 31 October 2011. Archived from the original (PDF) on 27 June 2016. Retrieved 17 January 2012.
- Levelt, Oct. 2011, p. 9
- Levelt, Oct. 2011, p. 6.
- "Diederik Stapel: The Lying Dutchman". The Washington Post (Post Opinions). 1 November 2011. Retrieved 17 January 2012.
- "Commissie onderzoekt Amsterdamse werk Stapel – Nieuws en Agenda – Universiteit van Amsterdam" (in Dutch). Uva.nl. 23 September 2011. Archived from the original on 27 November 2011. Retrieved 17 November 2011.
- Levelt, Oct 2011, p. 20
- "UvA onderzoekt mogelijkheid intrekken doctorsgraad Stapel – Nieuws en Agenda – Universiteit van Amsterdam" (in Dutch). Uva.nl. 31 October 2011. Archived from the original on 4 November 2011. Retrieved 17 November 2011.
- Callaway, Ewen (8 December 2011). "Report finds massive fraud at Dutch universities". Nature. 479 (7371): 15. Bibcode:2011Natur.479...15C. doi:10.1038/479015a. PMID 22051650.
- "First committee findings damn fraudulent Tilburg professor". Dutchnews.nl. 27 March 2012.
- "Stapel Investigation website", Joint Tilburg/ Groningen/ Amsterdam investigation of the publications by Mr. Stapel
- "Diederik Stapel heeft nooit excuses aangeboden" (in Dutch). nu.nl. 28 March 2012.
- "Hoe heeft Stapel de wetenschappelijke wereld voor de gek kunnen houden?". de Volkskrant (in Dutch). 28 November 2012. Retrieved 28 November 2012.
- "Psychologist admits to faking dozens of scientific studies". io9.
- Marcus, A. (1 December 2011). "Science drops other shoe in Stapel case, retracts recent paper on chaos". Retraction Watch. Retrieved 17 January 2012.
- Callaway, E. (1 December 2011). "Dutch psychology fraudster issues first retraction". Nature (Nature News Blog). Retrieved 17 January 2012.
- "Meat eaters are selfish and less social". DutchDailyNews.com. 30 August 2011. Retrieved 17 September 2011.
- "Meat eaters absolved, professor in the dock". DutchNews.nl. 8 September 2011. Retrieved 17 September 2011.
- Vanheste, Thomas (13 September 2011). "Onder psychologen" (in Dutch). Vrij Nederland. Archived from the original on 22 February 2013. Retrieved 31 October 2011.
- "Stapel betuigt openlijk 'diepe spijt'". Brabants Dagblad. 31 October 2011.
- Levelt Committee; Noort Committee; Drenth Committee (28 November 2012). "Flawed science: The fraudulent research practices of social psychologist Diederik Stapel" (PDF). Archived from the original (PDF) on 12 January 2013. Retrieved 14 February 2013.
- Jarrett, C., "Stapel – final report", in The Psychologist (News), Vol 26, Part 2 (February 2013), p. 88
- Drenth, P., Levelt, W. and Noort, E., "Flawed science?", in The Psychologist (Letters), Vol 26, Part 2 (February 2013), pp. 80–81
- Denny Borsboom and Eric-Jan Wagenmakers. "Book Review: Derailed: The Rise and Fall of Diederik Stapel" (PDF).
- Frank Huiskamp (28 June 2013). "Diederik Stapel treft schikking met justitie om vervolging te voorkomen". NRC Handelsblad. Retrieved 13 July 2013. (in Dutch)
- Yudhijit Bhattacharjee (28 June 2013). "Stapel Gets Community Service for Fabricating Studies". sciencemag.org. Archived from the original on 6 July 2013. Retrieved 13 July 2013.
- "Diederik Stapel now has 58 retractions". Retraction Watch. Retrieved 22 March 2017.
- "Retraction of "Terror Management and Stereotyping: Why Do People Stereotype when Mortality is Salient?," "Distinctiveness is Key: How Different Types of Self-Other Similarity Moderate Social Comparison Effects," and "When We Wonder What It All Means: Interpretation Goals Facilitate Accessibility and Stereotyping Effects"". Personality and Social Psychology Bulletin. 39 (2): 264. February 2013. doi:10.1177/0146167212474240. PMID 23386661. S2CID 206444897.
- Kreulen, Edwin (1 November 2011). "Diederik Stapel verzon list na list en duldde geen enkele tegenspraak". Trouw.
(English translation) Stapel knew at that moment exactly what he expected, which could be inferred yesterday from the words of Pim Levelt. 'The science article is based on fake data', was his verdict, just like at least 29 other publications by Stapel, and probably more. (Dutch original) Stapel wist op dat moment precies wat hij verwachtte, viel gisteren af te leiden uit de woorden van onderzoeker Pim Levelt. 'Het Science-artikel berust op gefabriceerde gegevens', was zijn oordeel, net als in ieder geval 29 andere publicaties van Stapel, en vermoedelijk nog meer.
- Stapel, D. A.; Lindenberg, S. (2 December 2011). "Retraction". Science. 334 (6060): 1202. doi:10.1126/science.334.6060.1202-a. PMID 22144595.
- Alberts, Bruce (11 November 2011). "Editorial Expression of Concern". Science. 334 (6057): 760. Bibcode:2011Sci...334Q.760A. doi:10.1126/science.1216027. PMID 22045832.
- Flawed Science. The fraudulent research practices of social psychologist Diederik Stapel. (Final Report of the Stapel Committees, November 2012)
- Frank van Kolfschooten; Ontspoorde wetenschap ("Derailed Science"); De Kring publishers; October 2012; ISBN 94-91567-02-0