Behrouz Mehri/AFP/Getty Images
Behrouz Mehri/AFP/Getty Images

Time of Day and Age May Influence Coffee's Impact on Memory

Behrouz Mehri/AFP/Getty Images
Behrouz Mehri/AFP/Getty Images

Many people knock back a cup of coffee every morning with the goal of doing better on a test or jumping into a backlog of work … or just to feel remotely human. Caffeine is the most widely used stimulant in North America—some 90 percent of the adult population consumes it for its mentally arousing effects. But a recent study published in Frontiers in Psychology has found that the time of day and your age may influence coffee's influence on your memory.

Memory, of course, is a key component of learning, retention, and performance in a number of areas of our lives. Explicit memory, lead author Stephanie Sherman, a postdoctoral fellow in the psychology department at Boston College, tells mental_floss, "is just conscious recall of info." Implicit memory, on the other hand, which researchers call "priming," is the unconscious recall of previously learned information. More specifically, if something you’ve recently encountered happens to be in the forefront of your mind, "you’re more likely to recall it without being conscious you recalled it because you previously saw it," she explains.

Sherman became intrigued by a study her professor Lee Ryan conducted that explored the relationship between caffeine and implicit and explicit memory in older adults. Ryan’s study showed that caffeine enhanced memory performance in older adults in their non-optimal time of day: the afternoon. But caffeine had no effect on their memory in the morning, Sherman says. She wanted to find out if this would hold true in young adults, whose circadian rhythms are different, making afternoon their optimal time of day for physiological arousal—essentially, in how awake they feel—and morning their non-optimal time.

To test this hypothesis, she and her colleagues designed a double-blind experiment with college students aged 18 to 21. The first group of students came into the lab between 6:00 and 7:00 a.m. Half of these participants received a cup of caffeinated coffee, and the others got decaffeinated; regardless of which cup they received, they were told their coffee was caffeinated. That procedure was repeated with a second group of 40 participants in the afternoon between 2:00 and 4:00 p.m. Sherman’s team theorized that caffeine would have memory-boosting effects for young adults in their non-optimal time of day—early morning—but to determine the specificity of caffeine’s effects, they also investigated the effects on memory performance of two types of exercise in the early morning—vigorous aerobic exercise and gentle stretching.

"We thought another way of increasing physiological arousal would be exercise. If just being more awake increases your memory performance, than exercise would have the same effect [as caffeine]," Sherman reports.

On arrival, participants reported how awake they felt on a scale from one (not awake) to five (wide awake). After drinking one cup of coffee, they began two memory tasks. The first was a word stem completion task, in which they looked at words and were asked to tell the researchers how pleasant the word was on a scale from one to five. This was what Sherman calls incidental encoding: "They’re not told why they’re viewing it except to rate the pleasantness of these words." The goal was to plant words in the participants’ minds for potential recall in the next test.

In the next test, for implicit memory, participants engaged in a word-stem completion test. Each participant would see a word root, such as bas, and have to complete the word. Twenty-four of the stems could be completed with words they had seen during the study phase. "So if they see bas, for example, and in the study phase they were primed and had seen the word baseball, they might say 'baseball,'" Sherman explains. "Otherwise, they might say 'basement,' 'base,' or any other world that starts with bas. That’s the test of implicit memory."

To test explicit memory, the scientists performed a cued recall test consisting of word stems which corresponded to words from the study list. If participants saw bas, for example, and remembered that during the study phase they’d seen baseball, they should have been able to recall baseball with ease.

To compare the effects of caffeine to exercise, participants in the second experiment engaged in approximately 15 minutes of cardiovascular exercise or gentle stretching during the early morning. The authors write, "If caffeine benefits explicit memory by increasing general physiological arousal, we would expect to see the same boost in memory performance after morning exercise."

The results should be encouraging to coffee addicts: Researchers found young adults who drank caffeinated coffee in the morning were 30 percent better at the cued recall test than their decaf counterparts were. They also reported being significantly more awake by the end of the experiment than those who drank decaf. However, the two groups showed no difference in the implicit memory test, and for those who performed their tests in the afternoon, caffeine did not make a significant improvement in either test.

Sherman says that several of their results were surprising: First, that caffeine did not have much effect on participants in their optimal time of day (afternoon). Sherman theorizes, "The idea is that if people are already at their optimal, some caffeine is not going to further increase performance. Caffeine only helped when you’re at your low point in the day of physiological arousal and performance." Also unexpected: Exercise did not improve memory performance either.

Sherman makes clear that this isn't a comprehensive study about caffeine’s relationship to memory or cognitive function. For starters, participants only drank one cup of coffee with 200 mg of caffeine (about average for a 12-ounce cup). Further research is needed to better understand the mechanisms of how caffeine impacts memory. Sherman says: "If people learn with caffeine and are tested with caffeine, does that make [their memory] is better? What if we tell people they are about to do a memory test and they have caffeine—will that be better? If we have people learn with caffeine and bring them in a week later, will we see an increase in performance? We don’t know the extent."

Similarly, they can’t speak to whether more coffee would increase memory performance rates, since participants only ingested one cup of coffee. "We don’t want anyone to get the idea that we should ingest five cups of coffee to get five times the performance," she cautions.

In short, when it comes to giving your memory a performance jolt, if you’re a college student taking an early exam, you may want to brew up a cup. But if you're over college age, late afternoon may be the best time for that coffee boost.

Pop Chart Lab
Epic Poster Charts More Than 500 Varieties of Beer
Pop Chart Lab
Pop Chart Lab

Pop Chart Lab has produced several beer-related posters, like the "Very Many Varieties of Beer" and the "Very, Very Many Varieties of Beer." They’ve outdone themselves again with their latest refreshing visualization. The new chart, titled "The Magnificent Multitude of Beer," organizes more than 500 individual beers into more than 100 different styles.

According to Pop Chart Lab, this latest poster is particularly expansive, listing two to five times as many beers as their previous charts. Even the most seasoned beer aficionado has something to learn from studying it. The product’s description reads:

“This ultimate beer chart breaks down every style of brew from hoppy IPAs to fruity Iambics. Now including ABV and IBU ranges for each style—as well as glassware recommendations!—this massive mapping of beer captures the delicious, awe-inspiring output of breweries around the world.”

All that information requires an appropriate package to contain it. The poster measures 48-by-32-inches—making it more than big enough to cover the wall behind your home bar. Hang this poster where you can see it and your well of beer knowledge will never run dry. You can preorder a print for $65, with shipping set to begin on February 15.

Chart of beer varieties.
Pop Chart Lab

Framed poster of beer varieties.
Pop Chart Lab
Public Domain // Mendhak // CC Attribution-Share Alike 2.0 Generic (Wikimedia Commons)
George Orwell's 11 Tips for Proper Tea Making
Public Domain // Mendhak // CC Attribution-Share Alike 2.0 Generic (Wikimedia Commons)
Public Domain // Mendhak // CC Attribution-Share Alike 2.0 Generic (Wikimedia Commons)

More than 70 years ago, in the January 12, 1946, edition of the Evening Standard, George Orwell wrote up 11 tips for making and consuming tea. Published under the title "A Nice Cup of Tea," Orwell noted that "at least four [points] are acutely controversial." That's a bold claim!

So what does it take to make an Orwellian cup of tea? Read on.


If you look up 'tea' in the first cookery book that comes to hand you will probably find that it is unmentioned; or at most you will find a few lines of sketchy instructions which give no ruling on several of the most important points.
This is curious, not only because tea is one of the main stays of civilization in this country, as well as in Eire, Australia and New Zealand, but because the best manner of making it is the subject of violent disputes.

When I look through my own recipe for the perfect cup of tea, I find no fewer than eleven outstanding points. On perhaps two of them there would be pretty general agreement, but at least four others are acutely controversial. Here are my own eleven rules, every one of which I regard as golden:


First of all, one should use Indian or Ceylonese tea. China tea has virtues which are not to be despised nowadays—it is economical, and one can drink it without milk—but there is not much stimulation in it. One does not feel wiser, braver or more optimistic after drinking it. Anyone who has used that comforting phrase 'a nice cup of tea' invariably means Indian tea.


Secondly, tea should be made in small quantities—that is, in a teapot. Tea out of an urn is always tasteless, while army tea, made in a cauldron, tastes of grease and whitewash. The teapot should be made of china or earthenware. Silver or Britanniaware teapots produce inferior tea and enamel pots are worse; though curiously enough a pewter teapot (a rarity nowadays) is not so bad.


Thirdly, the pot should be warmed beforehand. This is better done by placing it on the hob than by the usual method of swilling it out with hot water.

(Ed. note: a hob is a stove burner in this context. Depends a bit on what sort of pot you're using whether it's safe to put it on the burner!)


Fourthly, the tea should be strong. For a pot holding a quart, if you are going to fill it nearly to the brim, six heaped teaspoons would be about right. In a time of rationing, this is not an idea that can be realized on every day of the week, but I maintain that one strong cup of tea is better than twenty weak ones. All true tea lovers not only like their tea strong, but like it a little stronger with each year that passes—a fact which is recognized in the extra ration issued to old-age pensioners.


Fifthly, the tea should be put straight into the pot. No strainers, muslin bags or other devices to imprison the tea. In some countries teapots are fitted with little dangling baskets under the spout to catch the stray leaves, which are supposed to be harmful. Actually one can swallow tea-leaves in considerable quantities without ill effect, and if the tea is not loose in the pot it never infuses properly.


Sixthly, one should take the teapot to the kettle and not the other way about. The water should be actually boiling at the moment of impact, which means that one should keep it on the flame while one pours. Some people add that one should only use water that has been freshly brought to the boil, but I have never noticed that it makes any difference.


Seventhly, after making the tea, one should stir it, or better, give the pot a good shake, afterwards allowing the leaves to settle.


Eighthly, one should drink out of a good breakfast cup—that is, the cylindrical type of cup, not the flat, shallow type. The breakfast cup holds more, and with the other kind one's tea is always half cold before one has well started on it.


Ninthly, one should pour the cream off the milk before using it for tea. Milk that is too creamy always gives tea a sickly taste.


Tenthly, one should pour tea into the cup first. This is one of the most controversial points of all; indeed in every family in Britain there are probably two schools of thought on the subject. The milk-first school can bring forward some fairly strong arguments, but I maintain that my own argument is unanswerable. This is that, by putting the tea in first and stirring as one pours, one can exactly regulate the amount of milk whereas one is liable to put in too much milk if one does it the other way round.


Lastly, tea—unless one is drinking it in the Russian style—should be drunk without sugar. I know very well that I am in a minority here. But still, how can you call yourself a true tea lover if you destroy the flavour of your tea by putting sugar in it? It would be equally reasonable to put in pepper or salt. Tea is meant to be bitter, just as beer is meant to be bitter. If you sweeten it, you are no longer tasting the tea, you are merely tasting the sugar; you could make a very similar drink by dissolving sugar in plain hot water.

Some people would answer that they don't like tea in itself, that they only drink it in order to be warmed and stimulated, and they need sugar to take the taste away. To those misguided people I would say: Try drinking tea without sugar for, say, a fortnight and it is very unlikely that you will ever want to ruin your tea by sweetening it again.

Orwell concludes:

These are not the only controversial points to arise in connexion with tea drinking, but they are sufficient to show how subtilized the whole business has become. There is also the mysterious social etiquette surrounding the teapot (why is it considered vulgar to drink out of your saucer, for instance?) and much might be written about the subsidiary uses of tealeaves, such as telling fortunes, predicting the arrival of visitors, feeding rabbits, healing burns and sweeping the carpet. It is worth paying attention to such details as warming the pot and using water that is really boiling, so as to make quite sure of wringing out of one's ration the twenty good, strong cups of that two ounces, properly handled, ought to represent.

Let the arguing commence, tea lovers!


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