Posts

The riddle of emergence – where do novel things come from?

It’s not true, that there’s nothing new under the sun. The universe is producing novelty all the time. Galaxies, stars, and planets, where none existed before. New elements, new molecules – life itself, with the explosion of new species, and eventually new minds, capable of new thoughts. New types of things at new levels of existence – discrete entities composed of smaller entities, arranged in specific ways. New systems with new properties and new causal powers, governed by new principles. So where does all this novelty come from?   The term emergence is often used to refer to the appearance of qualitatively novel states or processes or properties that arise when things are combined in certain ways. But as with many metaphysical terms, it means different things to different people and in different contexts, and it’s not always clear what, if anything, follows from its use. In particular, it is often not stated whether “emergence” simply refers to an observed phenomenon in need o

Go big or stay home! Small neuroimaging association studies just generate noise.

Figuring out the neural basis of differences between individuals or groups in all kinds of psychological traits or psychiatric conditions is a major goal of modern neuroscience. In humans, investigating this has necessarily relied on non-invasive tools like functional or structural magnetic resonance imaging (MRI). Many thousands of studies have been published following a similar design: measure some functional or structural neuroimaging parameters across the whole brain and compare them across individuals or groups to look for ones that are statistically associated with variation in some psychological trait, performance on a cognitive task, or membership of one or other group. Most of these studies have sample sizes in the tens or at best the low hundreds. A new study by Scott Marek and colleagues shows convincingly that those sample sizes are at least one or two orders of magnitude too low to produce reliable results.   This shouldn’t really be news to anyone who’s been paying a

What have we learned from psychiatric genetics? The view from 2022.

It has been recognised for millennia that risk of mental illness (broadly defined) tends to run in families. Modern science has confirmed that psychiatric disorders of all kinds are highly heritable – that is, the majority of the variation we see across the population in who is at risk of developing these conditions is genetic in origin. However, these conditions are not inherited in a simple “Mendelian” fashion, with clearly segregating risk, like cystic fibrosis or sickle-cell anemia. Instead, their inheritance is “complex”, which means that many genetic variants are at play, along with non-genetic factors. In addition, despite clear familial risks in general, many individual cases are “sporadic”, with no affected relatives. The last decade has seen tremendous efforts by many hundreds of scientists across the globe aimed at identifying the genetic risk factors and better understanding the etiology of psychiatric conditions.   The hope is that elucidating the genetics of these con

Telling good science from bad – a user’s guide to navigating the scientific literature

“Did you find it convincing?” That’s what one of my genetics professors used to ask us, a small group of undergraduates who blinked in response, like rabbits in the headlights. We didn’t know we were supposed to evaluate scientific papers. Who the hell were we to say if these papers – published by proper grown-up scientists in big-name scientific journals – were convincing or not? We thought published, peer-reviewed papers contained The Truth. But our professor (the always inspirational David McConnell at Trinity College Dublin) wasn’t about to let us off so easily. We learned quickly that it absolutely was our job, as fledgling scientists, to learn how to evaluate scientific papers.   This is not a responsibility that can be offloaded to peer reviewers and journal editors. It’s not that pre-publication peer review, when it works as intended, doesn’t perform a useful function. But those supposed gatekeepers of knowledge are as fallible as the primary producers of the research itse