Drang naar Samenhang

Update April 3, 2025 This blog, Drang naar Samenhang will feature posts in Dutch from now on—but no worries, English speakers, I’ve got you covered too. I have launched Substack newsletter called  Craving Coherence :  https://rolfzwaan.substack.com . You don’t need to subscribe to read the posts—just hit  “No thanks”  if prompted. Of course, I’d really appreciate it if you  do  sign up. It’s completely free! So what is the newsletter about?  Why do we search for patterns, craft narratives, and cling to meaning? Craving Coherence explores the psychology of understanding—the mental shortcuts, biases, and frameworks that shape how we interpret reality. From cognitive science to philosophy, this newsletter examines how our minds construct coherence in an often chaotic world—and what happens when they fail. I hope to see you there! Back to the original post: About a month ago, I had a difficult conversation with my daughter. Her year in college had not g...

There are many differences between the scholarly cultures of the humanities and the natural sciences. One seemingly superficial but striking difference is in the number of authors per paper. A significant number of papers in the humanities are single-authored whereas in the natural sciences multi-authored papers are the norm; for some articles, the author list is longer than the article itself. For example, this paper on an experiment performed at the CERN Large Hadron Collider sports an army 2,926 authors, enough to fill two concert halls. In contrast to the natural sciences, publications in the humanities are typically single-authored; examples are essays in philosophy, linguistics, and literary criticism. Such scholarly endeavors are by nature individualistic. The author’s style of writing and argumentation play an important role. References to these essays are therefore often accompanied by quotes rather than by a dry summary of findings. It is apparently not only importan...

Can we capture any aspect of human psychology in a single number? In 1956 a paper entitled The Magical Number Seven Plus or Minus Two saw the light. It was destined to become a classic in cognitive psychology. In it, George A. Miller argued that human short-term memory is limited to seven units of information. The 7 was just an approximation, which is why Miller added the cautious plus-or-minus-two. In 1993 my former colleague Anders Ericsson wrote a much-cited  paper in which he argued that minimally 10 years of deliberate practice are required to achieve expertise in a domain, an idea that was popularized by Malcolm Gladwell. It is rare to tie psychological performance to a number, but Miller’s proposal is modest, as is Ericsson’s. The numbers are not claimed to be exact and are derived in a straightforward way from the data. There is another number in psychology that makes a lot less sense: the number 2.9013. It represents the ratio between positive emotions...

Along with getting tenure, the most important rite of passage in an academic career is the defense of the doctoral dissertation.  Across the globe, defenses range from academic inquisitions to folkloristic public events. Dissertation defenses in the Netherlands fall on the folkloristic end of the spectrum. This is because the defense and conferral of the degree are rolled into one event. The candidate’s family, friends, and department colleagues are in attendance and the eight or so committee members, including the candidate’s major professor, are wearing full academic regalia. Defenses in the United Kingdom are a decidedly more austere affair involving only the candidate and two external examiners; not even the major professor is allowed present. The examination I participated in took place in a small room in the bowels of a building. After the, successful, defense the candidate’s major professor and two lab mates suddenly appeared in the hallway with champagne...

There has been a lot of debate lately about effect sizes. On the one hand, there are effects in the social priming literature that seem surprisingly large given the subtlety of the manipulation, the between-subjects design, and the (small) sample size. On the other hand, some researchers can be heard complaining about small effect sizes in other areas of study (for example cognitive psychology). Why would we want to study small effects? This is not a new question.  We could go further back in history but let’s stop in 1992, the year in which an insightful article on small effect sizes appeared, authored by Deborah Prentice and Dale Miller. Prentice and Miller argue that there are two valid reasons why psychologists study small effects. The first reason is that researchers are trying to establish the minimal conditions under which an effect can be found. They accomplish this by minimally manipulating the independent variable.  The second reason is tha...