The frantic battle against college finals is fast approaching my brother and his friends. As they arm themselves with the Trinity of student weaponry – coffee, sleep and course notes – I would like to offer them some fun science about how these influence learning and memory, hoping it would inspire them into making informed adjustments to their studying habits. If nothing else, it would make for some enjoyable procrastination. Today, in the first post of this series, we host the best friend of many students: Caffeine.
When studying how your latte affects your memory, participants either drink or avoid coffee before they begin learning new material; later, their memory is tested and the researchers look for differences in memory between the caffeinated and non-caffeinated participants. These studies could be informative in telling you whether or not coffee affects your memory, but they are of limited benefit if you would like to know why such effects happen. To understand this problem, let’s think about how memories are formed.
To understand the multiple stages of creating a new memory, think of memories as pictures. Imagine that you want to document your birthday party by taking a group selfie with friends. You open the camera app on your smartphone and the camera sensors start detecting light reflected from the environment; but you first need to convert this light into a format that can be stored, such as JPEG. Then, you need to store this picture somewhere; let’s say you choose to store in on Facebook, in an album called “special events”. Next time you would like to see that picture, you will thus have to navigate your way to the correct album.
Just like a picture is a documentation of your birthday that you keep on Facebook, a memory is a form of documentation you keep inside your mind. When you create a new memory (e.g., of some material for an exam), the stages you go through parallel what you do when taking a picture:
First, you convert the information coming through your senses (the light reflected from the page you are reading) into a format that can be stored. This is called encoding.
Then, you keep the encoded information for future use, through a process of storage. Improving storage quality – making a memory more stable – is called consolidation.
Finally, you can recall what you memorized when you need to use it. This is called retrieval.
If your memory is affected by coffee, why does this happen? Does coffee improve your encoding? Does it optimize consolidation? Does it assist retrieval? If you drink coffee before you start learning new information, which is what you would do in psychological experiments, caffeine gets into your brain before any of these stages begin, so we cannot disentangle its separate effects on each stage. Luckily, two years ago a team from Johns Hopkins and UC-Irvine came up with an ingenious solution. Here is what they did:
When participants came to the lab, they were first shown some pictures of objects. After viewing them, some participants received caffeine while others received some ineffectual substance (a placebo). Neither the participants themselves nor the scientists interacting with them knew which person got which substance (a “double blind” study). A day later the participants, to their surprise, had a memory test: they were shown pictures, some of which were seen the day before (“old”) and some of which were not (“new”), and had to recognize the old pictures. The test had a catch: some new pictures were very similar to old ones – e.g., a picnic basket that looked much like the one seen the day before – but participants still had to realize they were new rather than old.
Participants who had coffee the day before and those who did not performed similarly on the easier parts of the test: they could tell apart old pictures from pictures that were clearly new. However, the caffeinated participants did better on the more difficult, confusing parts of the test: they were less likely to mistake the “catch” pictures for old ones. Importantly, because coffee was only given after viewing the pictures on the first day, it could not have influenced the encoding of the pictures. Moreover, if participants had coffee just before the memory test on the second day instead of during the first day, it did not improve their score on the difficult parts of the test. This result shows that coffee did not affect the retrieval stage – the ability of participants to access their memories. Therefore, the conclusion of this cleverly designed experiment is that caffeine improved memory consolidation.
So, having coffee may help you make stronger, more stable memories, even if you have it after you are done studying rather than before you start. By the way, the researchers found the ideal dose of caffeine for improving their participants’ memory consolidation was around 200mg.
MY TWO CENTS: keep in mind that this experiment was not designed to mimic studying for exams. First, the participants did not know that a test was coming. Second, they viewed pictures of objects, which were very different from the kinds of material college students engage with (even though you may claim that “catch” pictures are somewhat similar to “catch” answers in multiple-choice questions). Third, the participants were very infrequent users of coffee, so it is unknown whether coffee would have the same effects on the memory of those students who are used to a constant IV of caffeine. Still, don’t you think this study is awesome?
CITATION: Borota, D., Murray, E., Keceli, G., Chang, A., Watabe, J.M., Ly, M., Toscano, J.P., & Yassa, M. A. (2014). Post-study caffeine administration enhances memory consolidation in humans. Nature neuroscience, 17(2), 201-203.