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Recent posts
WARN-D machine learning competition is live
The crucial value of exploratory research
Cutting international bachelor programs threatens psychological science
The darkness that comes before
Are causes of mental disorders in the person or in the environment?
Playing the alphabet factor game: the S factor for satisfaction
Zombie theories: why so many false ideas stick around
No evidence for a psychological trait of impulsivity
Popular posts
Are causes of mental disorders in the person or in the environment?
Zombie theories: why so many false ideas stick around
A checklist to vet psychedelic science
Antidotes to cynicism creep in academia
Welcome to Hotel Elsevier: you can check-out any time you like … not
On Theory
Academia: trapped in the upside down of publishing
All mental disorders are brain disorders … not.
Blog archive
WARN-D machine learning competition is live
If you share one single thing from our team in 2026—on social media or per email with your colleagues—please let it be this machine learning competition . It has taken more than...
The crucial value of exploratory research
In a recent interview with Zhixian Lian from the Chinese Social Sciences Today (CSST), I was asked a number of questions about the value of exploratory research. You can find my...
Cutting international bachelor programs threatens psychological science
Two days ago, five Dutch universities announced discontinuing their English-speaking psychology bachelor programs ( 1 , 2 , 3 ). Here I will briefly explain how this decision came...
The darkness that comes before
"We are all subject to the fates. But we must act as if we are not, or die of despair." –Philip Pullman, The Golden Compass 1. The darkness that comes before Your life is shaped...
Are causes of mental disorders in the person or in the environment?
We just published a new paper in JoPACS on the importance of socio-environmental causes of psychopathology ( PDF ), with the brilliant Merlijn Olthof and Anna Lichtwarck-Aschoff ...
Playing the alphabet factor game: the S factor for satisfaction
I also wanted to make a name for myself in the competitive field of alphabet factoring in psychology. G factor. P factor. I factor . D factor . Aaaaall the factors. My recent list...
Zombie theories: why so many false ideas stick around
When I talk to friends or family members who do not work in academia, they have beliefs about how science works — beliefs that appear entirely sensible. Most published results are...
No evidence for a psychological trait of impulsivity
This is a brief commentary by Orestis Zavlis (Psychology and Language Sciences, University College London, United King) and me on the recent PNAS paper entitled "Impulsivity is a...
Red flags in the new 2024 depression Ketamine paper
A short blog post for a change, with the goal to preempt expected hype around what is basically a null-finding: Nature Medicine just published a new paper on using Ketamine for...
A checklist to vet psychedelic science
As result of a commentary we wrote, Jama Psychiatry recently published a correction of a serious error in a 2023 paper on treating bipolar depression with psilocybin (together...
2022 psilocybin Nature Medicine study remains uncorrected
I just saw that the Daws et al. 2022 paper that was heavily discussed in 2022 and 2023 is still online, and Nature Medicine neither published criticism that has been raised, nor...
Social media bans don't address youth mental health problems
I co-wrote this piece with the fantastic Margarita Panayiotou , Senior Lecturer at the University of Manchester who's work focuses on psychometrics, measurement, social media &...
Scientific publishers *not* adding value
A month ago, I wrote about things that bum me out in academia, and some antidotes against cynicism creep . It was actually one of my best-received blog posts, and I appreciate all...
Which depression measure is best?
A new paper published today in Lancet Psychiatry , led by Christopher Veal, reports findings from a systemic review of 450 clinical trials for unipolar and bipolar depression. Our...
Antidotes to cynicism creep in academia
This is one of these blog posts that doesn't read well if you stop halfway. First, I provide evidence that academia can look pretty broken: there is low-quality work everywhere...
Blood tests for mental health problems
A new paper was published yesterday on a blood test for schizophrenia, by the same research team that in 2021 published a paper on a blood test for depression . The papers and...
Fact-check: depression & temperatures study
A new interesting paper was published 2 weeks ago on depression and temperature. I saw a news article about the paper today that I didn't think captured the core findings...
Is the 'default mode network' responsible for the mental health crisis in youth?
(Note: I wrote up this blog as a commentary, which is now published in the same journal as response to the editorial. PDF , DOI 10.31234/osf.io/eycvw) The very short answer is...
Does the d (disease) factor really exist?
Mental health problems are comorbid, which means that they are positively intercorrelated and don't tend to occur in isolation. Of all people diagnosed with major depression, for...
Using GPT-3 to search for scientific "references"
I have been playing around with GPT-3 and its chatbot in previous weeks, and found it fascinating. GPT-3——the Generative Pre-trained Transformer 3——is a deep learning language...
"Clear evidence" for serotonin hypothesis of depression?
There has been a 60 year long discussion on the role of the neurotransmitter serotonin in the pathophysiology of depression. A recent systematic investigation by Joanna Moncrieff...
Measurement error in network models
It's been a while since I wrote a blog post on a new paper, but the recently published paper of Jill de Ron et al. investigates limitations of network models discussed for a good...
Welcome to Hotel Elsevier: you can check-out any time you like … not
In December 2021, Robin Kok wrote a series of tweets about his Elsevier data access request. I did the same a few days later. This here is the resulting collaborative blog post...
Award for transformative early career contributions
About a year ago, the Association for Psychological Science awarded me with the Janet Taylor Spence Award for transformative early career contributions to psychological science...
Treating depression with psychedelics: red flags and FAQ
Update, 02/2024: We have now published the paper " History repeating: guidelines to address common problems in psychedelic science " on this topic, in part based on this blog post...
Creating basic psychometric summaries in R
We just finished collecting the first cohort of the WARN-D study , our ambitious effort to create a personalized early warning system for depression. In the 90 minute self report...
Schmeasurement: DSM-5 symptom measure edition
For our new WARN-D research project on building a personalized early warning system for depression, I recently looked into openly available, transdiagnostic, self-report mental...
1 minute science communication video .. only using legos
Young Academy Leiden challenged its members—including yours truly—to make a video about an upcoming research project, with two constraints. First, we only have one minute to...
On Theory
What is a good theory, and what is a bad one? In this blog, I'll introduce theories, models, phenomena, data, and how they relate to each other. I'll explain what Paul Meehl, the...
Modeling idiographic and nomothetic dynamics of 255 depressed inpatients
Led by the first author Kaat Hebbrecht , we published an open access paper a few days ago on "Understanding personalized dynamics to inform precision medicine: a dynamic time warp...
Measuring depression outcomes that matter to patients, caregivers, and healthcare professionals
Our team led by the brilliant Astrid Chevance just published a new paper, entitled "Identifying outcomes for depression that matter to patients, informal caregivers and healthcare...
COVID-19 pandemic and student mental health
The goal of this blog post is to summarize our recent study on COVID-19 and student mental health, and do a bit of science translation of our core findings. You can find the final...
APA chief publishing officer: ignore paper removal request
On December 24th 2019, I received a legal threat by the American Psychological Association to remove one of my papers from my personal website. Similar requests have been received...
The replication crisis hits psychiatry: No candidate genes for depression
A new study on candidate genes for depression was just published in the American Journal of Psychiatry by Border et al , entitled "No Support for Historical Candidate Gene or...
First preregistered network replication study with power analysis & open data
I haven't written blog posts about individual new papers in over a year, but this one is a milestone I'm really proud of: Our new network paper on social media and well-being was...
The Myth of the Miracle Cure: Is Ketamine an Efficacious Antidepressant?
This blog post is the result of a collaboration between Dr Lucy Robinson ( Twitter , email ) & me . Life with depression can be miserable, painful and sad. The suffering it causes...
James Coyne sued me for cyberbullying
In this blog, I first describe the formal complaint of Dr James Coyne against me, launched a week after my blog post about tone on social media in August 2017. Coyne claimed that...
Failure of the week
In our Clinical Psychology group in Leiden, we have the tradition to share new papers, accepted grant proposal, and other achievements in emails called "Paper of the Week", "Grant...
10,377 ways for major depression, but 341,737 ways for melancholia
We wrote up the core arguments and calculations of this blog post as an article for Lancet Psychiatry. Major depression: a highly heterogeneous disorder Major Depressive Disorder...
7 Sternberg papers: 351 references, 161 self-citations
Robert Sternberg, editor-in-chief of Perspectives on Psychological Science (PoPS), published 7 papers in PoPS in the last 2 years. The papers contain 351 references; 161 of these...
Academia: trapped in the upside down of publishing
TL;DR: this post explains the basics of academic publishing; highlights several severe problems; discusses the recent activities of the American Psychology Association (APA)...
Assistant professor, APS rising star, and some papers
Three brief personal updates. After living in 6 countries in the last 12 years; after affairs and short relationships with Ludwig Maximilian's University Munich, Free University...
All mental disorders are brain disorders … not.
Summary: Mental disorders are commonly defined as "brain disorders" in the literature. I show in this blog that this notion remains speculative, and share a 10-week syllabus /...
When small samples are problematic
A few days ago, Richard Morey started a discussion on Twitter arguing that small samples are not inherently problematic. In the interesting discussion that ensued, I kept thinking...
Are we asking too much? A list of competencies people expect me to have
Working between disciplines is exciting, and I wouldn't want to have it any other way. Psychology has become much more interdisciplinary in recent years, and there was a...
The tone-police police, rude dudes, & how to be social on social media
TL;DR : The tone-police police on social media must take responsibility for silencing early career folks in psychological science debates on social media. I also talk about rude...
Supplementary materials fail
A few months ago, we published a new paper Fried, E. I., van Borkulo, C. D., Cramer, A. O. J., Boschloo, L., Schoevers, R. A., & Borsboom, D. (2017). Mental disorders as networks...
Ketamine as promising treatment for suicidal thoughts?
Imagine you are a group of scientists and want to find out whether a novel drug X works on a specific problem Y. You run the following study: You enroll a small sample of 14...
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