transcript of episode 28: BIG, WRONG AND BORING, 23rd May 2022

[🎶 INTRO: "Spring Swing" by Dee Yan-Kee 🎶]

welcome to the error bar: scraping through the brain news barrel bottom

in this episode: the biggest brain scanning study ever, how the error bar was wrong, how magnetically stimulating the head is distracting & some vaguely-interesting news stories

here is the brain news on the 23rd May 2022:



the leading science magazines, New Scientist, Scientific American & the Daily Mail all reported on the largest-ever study to create a reference database of human brain growth across the whole lifespan. a remarkably huge 124 thousand brain scans were combined into lovely curvy lines showing how the brain changes size & composition over time.

continuing a theme, 2022 seems to be the year of big data at the error bar. we had the 1.8 million adults doing the 'implicit association test' (badly); 50 thousand brains in a study suggesting (unjustifiably) that most other scanning studies were too small; now a majestic 124 thousand more.

the scientific paper, in Nature magazine, was written by 201 scientists. my mind boggles at the effort, coordination & computing power it took to assemble & manipulate this dataset.


is this the biggest, beautifulest data of them all?


unlike the two previous 'big data' studies where the error bar had quibbles & concerns, here i take off my hat. this is big, beautiful, simple science. no strong claims seem to be made. rather, the data are just put out there for all to see.

scientific journals & societies often have requirements that new papers must be driven by a clear hypothesis, must test a theory experimentally, or make some theoretical advance. such journals may explicitly refuse to publish 'merely observational' studies. studies that just ask what things are like & how they change. would those lowly, technical journals refuse to publish something like this paper? a merely observational data-gathering exercise, but on a massive, magnificent scale.


behold the big data


the science was by Bethlehem et al. 2022: Nature; reported in The New Scientist by @CarissaCWWong on 6/Apr/22



approximately once per year, the error bar makes a mistake. this year's mistake was made in episode 27, specifically in the story, reported by the New Scientist, about how "Brain scanning studies are usually too small to find reliable results".

i summarised that news article & the scientific paper it was based upon in my headline "ALL BRAIN STUDIES ARE TOO SMALL". because of the way i have set up the error bar website, the database & the code that automatically creates tweets & posts them on the web, this came out on twitter as "ALL BRAIN STUDIES ARE TOO SMALL says the New Scientist."

but they did not say that. this was a twitter bot malfunction & i apologise.

what they did say is:

first, that "Brain scanning studies are usually too small to find reliable results". this headline is a bit too vague, not mentioning the specific kind of study that was relevant. it is not all kinds of brain scanning study, just some kinds.

the article's sub-title clarified which studies were relevant, but made a statistical mistake. it read: "Most studies that have used MRI machines to find links between the brain’s structure or function and complex mental traits had an average of 23 participants, but thousands are needed to find reliable results". the first part of the subtitle doesn't make sense - most studies don't have the average number; the average is calculated across all studies. the second part of the headline is also impossible to verify. unless we are certain about the true relationships that exist - something that almost never happens in science - how can we say we don't have enough data, or that the data we do have are unreliable?

i am picking holes, of course. but these holes matter, at least to me. my impression, from reading both the original article & the news coverage, was that the central claim is that most brain scanning studies of this kind were too small.

i don't agree. re-analysing three large & unfocused brain scanning studies, searching for post-hoc brain & behaviour correlations, tells us only that the data from those three studies were not sufficient; if we repeat exactly those three studies we would need thousands of MRI scans to find the post-hoc effects that the Nature paper found. what it doesn't tell us is how many MRI scans you would need if you had a better, or even the ideal dataset. the true effect sizes are out there to be discovered & we should not be dissuaded by their claim that you will need thousands of scans.


to err is human


and the brain in brief...



the scientist dot com reports - briefly - on a brain stimulation & artificial language study which claims that distracting people improves learning. in the paper, participants listened to a stream of seemingly-random words & syllables that combined into words, while they were watching the video Planet Earth with the sound off.

before listening to these novel sounds, the participants' heads were stimulated with a powerful electromagnet, 600 times in 30 seconds. the aim of this was to disrupt the cognitive mechanisms in the brain that normally prevent us from learning these random-sounding sounds. these cognitive mechanisms are thought to be in the prefrontal cortex - an important part of the brain involved in thinking.

the results are a little hard to wade through, but the headline finding is that brain stimulation, or cognitive distraction, makes you better at learning these new hidden word sounds. brain stimulation done on a different, also less distracting, brain area was used as a comparison.


is disruption good for language learning?


i struggled to follow the logic & the results a little bit - language is not really my topic. but brain stimulation is. so, let me just say this.

after 40 years of brain stimulation research it is, frankly weird, that scientists are still not using sensible control or comparison conditions. when the head is stimulated with an electromagnet, some locations on the scalp produce almost no sensations or muscle twitches; other locations produce strong contractions in the scalp, face, jaw or neck; some locations produce pain.

if you're stimulating a scalp location with some of these side-effects, it would be basic scientific good practice to choose a control or comparison location that had a similar level of twitchiness, pain & distraction. especially if your study is *about* distraction.

it is a puzzle, then, that some researchers still use the top of the head - the so-called vertex - as a control location when that spot is among the least-annoying locations, as a comparison for the prefrontal cortex, which is one of the more annoying locations.

in a second error, the authors of this study referred to a paper in support of the particular kind of brain stimulation that they used. but this cited paper did not use what they said it did, nor did they find the results that the authors said they found.


details, people, details.


the science was by Smalle et al. 2022: Proceedings of the National Academy of Sciences of the United States of America; reported in The Scientist by @ce_offord on 4/Apr/22



the error bar has been closed for several months. i'm sorry. i have kept myself busy: writing, submitting & publishing papers & working on The Book. more on those stories in future episodes.

for now, in place of a well-researched brain news story, here are three somewhat-interesting pieces of news.

first, the Daily Mail asked if the cause of hunger-related human irrationality - or hangriness - has finally been found. the answer is 'no', because the study they are referring to was about the MML-1 and HLH-30 transcription factors in 1mm-long worms. not about human hunger or rationality.

second, the journal Perception, founded by the late Professor Richard Gregory in 1972, celebrated its 50th birthday. if you're after illusions, historical anecdotes & sensory science, then Perception is the journal for you.

& finally, just in time for the English summer garden party season, the Daily Mail helpfully promotes the exceptionally-high quality & unbiased science that lies behind the announcement, from a leading high street sandwich maker & a leading potato crisp (or chip) manufacturer, that Chicken Tikka & Ready Salted crisps (or chips) are optimal in sandwiches.


things can only get better


reported in The Daily Mail by @shivalibest on 5/May/22, & The Daily Mail by @shivalibest on 21/Apr/22

[🎶 OUTRO: "Cosmopolitan - Margarita - Bellini" by Dee Yan-Kee 🎶]

it's closing time at the error bar, but do drop in next time for more brain news, fact-checking & neuro-opinions. take care.

the error bar was devised & produced by Dr Nick Holmes from the University of Nottingham. the music by Dee Yan-Kee is available from the free music archive. find us at the error bar dot com, on twitter at bar error, or email talk at the error bar dot com