The study

We can learn without even knowing that we’ve learnt something. For example, someone growing up in the UK without any musical training can probably recognise the basic tone patterns within western music, even if they don’t realise it. This type of learning is implicit learning, and it can be fairly robust — much more robust, in fact, than the explicit learning on which most classroom instruction is based.

The question posed in this study was whether such implicit learning is affected by how hard the brain is working on another task — the “cognitive load”, as the authors put it. Can the brain still learn when its resources are stretched on other tasks?

To test this, Marta Garrido and colleagues strained the brain by having participants perform a visual working memory test (the n-back task, with n = 2). At the same time, participants were played auditory tones, but were told to concentrate only on doing the visual task as well as they could. Most of the tones they heard fell within a certain range of each other, say one octave, but occasionally, at random times, a tone from two octaves away was played. If the participants’ brains showed surprise when these “oddball” tones occurred, the hypothesis was that they must have implicitly learnt the structure of the sounds they were played (i.e. that most tones fell within one octave of each other), even while they focussed on something completely different — the n-back task.

Using EEG to measure brain activity and surprise responses, this is exactly what was shown. Even when the brain was taxed by the visual test, and even when participants weren’t concentrating on what they heard, their brains still registered surprise when the oddball tone was played. In other words, implicit learning occurred even when the brain was concentrating on something completely different.

The bigger picture

It’s important to remember that these results concern implicit learning, not the explicit learning typical of the classroom. We know from experience that if a student is watching YouTube while a teacher covers calculus for the first time, not much calculus will be retained.

So from an education perspective, what can we take from this study? One thing that would be great to know is why implicit learning can occur even when the brain is otherwise occupied, as this might give us clues as to what prevents explicit learning when distractions occur. Alternatively, finding a way to incorporate implicit learning into the classroom could make the learning may help teachers devise strategies so that their students retain new information even when dsitracted.