pairs of people had their brain activity recorded while taking turns to discuss controversial topics on which they agreed or disagreed. flaws in the experimental design render the results difficult to interpret. convince me otherwise  

original article: Hirsch et al., 2020 (Frontiers in Human Neuroscience), reported in: The Wall Street Journal by Susan Pinker on 11th February 2021

this story was in episode 4 #fNIRS #agree #disagree #speech

the error bar says

the psychologist Susan Pinker, writing in her column in the Wall St Journal, reports on a study of people having their brains scanned during discussions of controversial topics

the 19 familiar pairs were selected for agreeing on two, and disagreeing on two controversial political or social topics

they discussed these four topics, taking 15 seconds at a time in a carefully-orchestrated turn-taking discussion

while they did so, optical brain imaging was performed on both sides of their head. the data were separated according to whether the topic was one on which they agreed or disagreed, and whether they were currently talking or listening

the results revealed a number of (not very surprising) things - mostly that regions of the brain known to be involved in speaking and listening were activated during these conversations

do arguing brains reveal something?

not really, no

the study suffers from a fundamental flaw that makes it very difficult to compare the different experimental conditions - there was no baseline condition against which to compare each of the other conditions. so, while the authors talk about the 'neural correlates of talking or listening or agreeing or disagreeing', they can only really talk about the differences between talking and listening, or between agreeing and disagreeing

if this doesn't sound like a problem, then consider cheese. two people could both like cheddar cheese a little bit more than they like wensleydale cheese. but one of these people could really hate both cheeses, and the other could really love both cheeses. if we only look at the differences between cheddar and wensleyday, we can't tell if they actually like cheese. the brain is the same

so the study is unable to tell us, for example, if any brain areas are involved in both talking and listening, or both agreeing and disagreeing. all we know is that some brain areas do different things in the two conditions

but more importantly than the data, both the scientific and the Wall St Journal articles both claimed that you can't get two people into the same MRI scanner. not true. the first MRI of a heterosexual couple having actual sex was in 1999, the first custom two-person scanner was described in 2011, and there are dozens of articles on two person MRI. just alta vista it


while the neural correlates of agreement and disagreement would be extremely interesting to the error bar, this study doesn't seem able to tell us much more than what we already know about talking and listening


The Wall Street Journal: fair - scientific story mostly intact