What does sex have in common with learning a new language?

The punchlines almost write themselves…

As someone married to a non-native English speaker, I feel duty-bound to attempt to learn my wife’s language. But, as with so many things in life, my motivation to actually knuckle down and learn is ever an issue. Perhaps because of this, the Daily Mail’s online headline “Yes! Oui! Si! Learning a new language activates the same part of the brain as SEX” certainly caught my monolingual eye. It goes on to further claim that “A new study suggests that learning a new language stimulates the same part of the brain as having sex or eating chocolate.” So how do these claims match up to the science behind the story?

The scientific article (predictably not linked in the news piece), which was made available last week in the prestigious journal Current Biology, examined brain activity in 36 adult participants as they learned a new language. Sort of. What they really did was to learn to associate a made-up word with a particular meaning, if that meaning was presented in a consistent fashion over 2 consecutive sentences, and press a button. If the meaning wasn’t consistent over the two consecutive sentences, participants were told to press a different button. This process was repeated plenty of times, and researchers examined the brain regions which showed most activation in those trials where a meaning was correctly learned as compared to when there was no meaning to be learned at all.

The ubiquitous ‘brain activation’ figure presented in the Mail piece (a composite of several figures from the paper, including one which doesn’t appear in the article, presumably created for the press release) shows the activation which is greater when the meaning is consistent (i.e., can be learned, in red-yellow) than when it isn’t. This ‘language learning activation’ is overlaid on top of the activation seen when winning vs. losing on a simple gambling task (in blue). Again, sort of. In fact, what is presented in this figure is the activation seen only in the region of the brain which cared about the gambling task (called a ‘Region of Interest’ analysis). This might seem like a bit of an inconsequential subtlety, but when you consider that the journal article reports 10 different brain regions which showed significant activation for the word-learning task, only 2 of which are involved in the gambling task, the headline looks a bit… sensationalist. In fairness, I’d be reluctant to lay the blame fully at the door of the reporters here – this is rather a misleading brain picture to throw at someone who won’t have read the journal article carefully. And, despite occasional debates in the literature about statistical circularity, this is a perfectly legitimate way of making sure you find subtle effects. If you can access the paper (it is behind a pay-wall), the top panel of Figure 2 is a more accurate representation of the neuroimaging data as it is presented in the news coverage – still pretty compelling, but not nearly so impressive (the areas activated for the language task are dwarfed by those activated during the gambling task, and seem heavily lateralized to the left hemisphere).

A few issues here worth dwelling on. For one, are we comfortable with the assertion that if a particular brain region ‘lights up’ in two separate tasks, then both tasks must have something in common? This logic, which is seen reasonably often in press reporting of neuroscientific findings, is known as reverse inference. Sadly, the logic only holds if that particular brain area has no other function, and is only involved in a single cognitive process. And decades of cognitive neuroscience research indicates that brain areas are routinely activated by a multitude of varied tasks (the ventral striatum, the region which is implicated in the current work, also plays a role in movement planning and movement execution). That is not to say that the ventral striatum does not play a role in enjoyable activities – it is one of the structures regularly implicated in reward and motivation processing in drug addiction and orgasm (again though, these are complicated behaviours involving many many different brain regions). The problem is the implication that learning a language is anything like sexual pleasure (or gambling, for that matter) based on similar-looking activation of a particular brain region.

Another issue which is hardly unique to this particular news story, is just how far beyond the remit of the press release it goes. Stating that “learning a new language stimulates the same part of the brain as having sex” is just plain wrong. The use of the word ‘stimulates’ is particularly troubling, due to the connotations of a causal relationship between the two. It would be more accurate to say that these brain regions are both involved, and leave aside the thorny issue of whether brain activity is caused by, or a consequence of, cognitive processes. More bizarrely, the news article also posits the out-of-the-blue suggestion that the research could “…explain why, as people grow older, they are still motivated to learn new words and communication techniques”.

P. Ripollés, J. Marco-Pallarés, U. Hielscher, A. Mestres-Missé, C. Tempelmann, H.- J. Heinze, A. Rodríguez-Fornells and T. Noesselt (2014). The Role of Reward in Word Learning and Its Implications for Language Acquisition. Current Biology, advanced online article. DOI: 10.1016/j.cub.2014.09.044