Last week I wrote about the potential impacts of caffeine (in coffee and energy drinks) on students and their study (here). In short, however, these were what I considered the most relevant findings:
Keleman and Creeley (2001)found that Caffeine reliably improves hit rates for sustained attention, that there was an interaction between caffeine and free recall IF caffeine was administered during the recall phase as well as the prep phase, and that caffeine did not impact of the accuracy or magnitude of accuracy predictions. As a student improving sustained attention is important, and the other points are interesting.
Oei and Hartley (2005) considered how ones expectation of the impact of coffee might alter its impact. They found that it helped in signal detection and reaction time, but not with memory. These results, as I suggested last time, were more relevant to air-traffic controllers than students. The key finding here is that message seems to have no impact – that is, placebo = good.
Finally, Warburton, Bersellini & Sweeney (2001) found that an energy drinks improved attention and verbal reasoning the sugar (nondiet) drinks compared to the no-sugar (diet) equivalents. They also found better, and faster, recall.They reported less variability than in similar coffee studies. Again, they found no improvement in memory.
So, I thought I’d explore the possibility that some caffeine drinks are better than others for study. And so here’s the general outline of my study:
- I kept the study content consistent (Evolutionary Psychology – Much reading and digestion, very little application)
- Each day I underwent a different condition. Conditions included: Large and Medium Coffee (Caffeine content unknown), Diet and Non-Diet energy drinks, a sugary (no caffeine) control, and a no-drink control.
- In a running addition to the experiment (based on ongoing results) I also drank a familiar, and preferred brand of energy drink.
- I ate prior to consumption of all drinks
What I found:
Variable, depends on how tired I am, etc. Generally, though, I reach a particular threshold where I think “I need caffeine to keep going”. We all know this feeling.
Large Coffee (with 2 sugar)
This was a larger dose than I typically drink. The drink was consumed over 25 minutes (roughly). I felt highly stimulated to the point of over-stimulation (at times), but also had a significant improvement in my affect (I felt good/positive). Initially, I was highly distractable, but that eventually subsided. The felt the quality of my work (comprehension, etc) was not as good as control, or other conditions.
Medium Coffee (with 2 sugars)
My typical dose. Consumed over 20 minutes or so. I felt a noticeable lift in my alertness and concentration, which ran a fine line between being overstimulating and useful. Affect improvement to a lesser degree than above. Quality of work fairly high.
Energy Drink (Redbull, non-diet)
Redbull was chosen as it has a non-sugar counterpart, but is not my drink of choice. I drank the 330ml bottle, which contains 160mg of caffeine. Consumed over 5 minutes. I got a headache, my vision became sensitive to the screen (but was relieve after putting on readers). I didn’t feel exceptionally stimulated (as with coffee), though I did feel ‘focused’ – but not necessarily engaged or as if I was comprehending as well as normal. I felt quite ‘gluggy’ at one point, and felt like I needed to sleep. That was unexpected.
Energy Drink (Redbull, diet)
330ml; 106mg caffeine; consumed over 5mins. Big improvement in affect. Felt really focused, with low distractability, though it did take a period of concentrated focus to get over some initial flittiness.
Energy Drink (Mother, non-diet)
My drink of choice. 500ml, 160mg Caffeine. Consumed over 5 minutes. Big improvement in affect and focus, though sometimes slightly overstimulated. Get a little shaky (sometimes) about 90 minutes after consumption.
Sugar (No caffeine) control
Ice-tea. Cool and refreshing during consumption. No effects otherwise.
The Big Coffee and the Non-diet energy drink were basically counterproductive.
The Diet energy drink, the familiar (large) energy drink, and the typical coffee were productive.
Control group and Sugar (no caffeine) equivalent.
This says a few things to me. First off, more caffeine is not necessarily better; but neither is less. The large coffee was bad, as was the non-diet energy drink – but the familiar (and large) Mother was productive. This says to me familiarity is better than unfamiliarity.
Secondly, diet was better than non-diet in the unfamiliar energy drinks, but the Mother was better (perhaps only marginally) than the diet variation.
Thirdly, the context of drinking the coffee is normally social, and not while I’m actually studying – so the undesirable effects occur during the social event and I come back after they’ve peaked.
It seems that my expectations played a big role – in the sense that if in the past I have had a good experience, I was likely to repeat it. I became either over sensitive to new drinks (or variations on old drinks), or they actually had a significantly different impact on me. I can’t know.
My conclusion is that I ought to stick with what I know to be effective. Caffeine is a habit forming drug, and maintaining those habits seems more beneficial than manipulating them to greater effect. In agreement with the literature I don’t believe my memory improved, and in some instances I was overstimulated and my attention and comprehension suffered. The biggest benefit, I think, is the general lift in mood. I believe it allowed me to remain motivated to study, even though my capacity to do so what diminished (in some conditions).
An interesting outcome. Though, personally, a little disappointing. It seems I was doing what was best in my situation already – but this appears (if my conclusions are sound) to be based almost exclusively on learning and conditioning, than specific drug effects. Though disappointing, I would argue that sometimes it’s a productive exercise to eliminate sub-optimal outcomes.
Next week my exams begin (after 3 weeks of intense study). They occur over three consecutive days. If I’m light on the blogging after next monday, forgive me (assuming you pay attention) – but wish me luck at any rate. Over the holidays I hope to come up with some new and more interesting explorations.
Tags: attention, coffee, drugs, Results
Kelemen WL, & Creeley CE (2001). Caffeine (4 mg/kg) influences sustained attention and delayed free recall but not memory predictions. Human psychopharmacology, 16 (4), 309-319 PMID: 12404566
Warburton DM, Bersellini E, & Sweeney E (2001). An evaluation of a caffeinated taurine drink on mood, memory and information processing in healthy volunteers without caffeine abstinence. Psychopharmacology, 158 (3), 322-8 PMID: 11713623
Oei A, & Hartley LR (2005). The effects of caffeine and expectancy on attention and memory. Human psychopharmacology, 20 (3), 193-202 PMID: 15742338