Cognitive Daily would not exist without chocolate. Every week, I buy a bag of chocolate covered raisins, and I portion them out precisely each day so that I’ve finished them by all by (casual) Friday. I try to time my consumption to coincide with the most difficult part of the job: reporting on peer-reviewed journal articles. The little news items, Ask a ScienceBlogger responses, and other miscellaneous announcements can be completed unassisted by chocolate, but then there wouldn’t be much reason to visit the site. Sometimes even the chocolate raisins aren’t enough, and I head for the nearest coffee shop for a cookie or other chocolate treat to further lubricate the writing apparatus.
While I can anecdotally say that chocolate helps me write, actual research on the impact of chocolate consumption tends to focus on negative effects: cravings, effects on weight, or tiredness. But Michael Macht and Dorothy Dettmer have partially rectified that problem with a simple little experiment on the emotional effects of chocolate consumption.
Thirty-seven female German college students volunteered to report on their mood and emotional states before and after eating chocolate or apples twice a day for six days. They were given 12 envelopes with a set of five surveys each. For each experimental session participants opened one envelope. After completing the first survey, which asked them to rate 12 feelings like hunger, boredom, fear, joy, and guilt, on scales of 0 to 7 as well as an overall “mood” rating, on a scale of 0 (extremely bad) to 10 (extremely good), they were instructed to eat either an apple, a Ritter Sport chocolate bar, or nothing. Then they set a timer which would remind them to complete the survey again 5, 30, 60, and 90 minutes after eating (or not eating). They were instructed not to eat for 1 hour before opening the envelope, and were not allowed to eat anything other than the chocolate or the apple until the last survey was completed.
So what was the effect of the chocolate consumption? This first graph shows the predictable chart of hunger ratings:
So that individual ratings could be compared, all of the ratings were normalized to zero at the outset of the test (in other words, the researchers subtracted the initial rating from each subsequent rating, so the chart is actually showing change in hunger from the initial state). Eating chocolate decreased hunger more than an apple, and its effects were longer-lasting. This isn’t especially surprising, since a chocolate bar has 270 calories, while an apple has just 90. It would be interesting to see if the same effect held after consuming just 90 calories worth of chocolate.
But now take a look at this chart showing impact on mood:
Eating chocolate resulted in an immediate elevation in mood, much stronger than that associated with eating an apple. What’s more, this difference spanned the entire duration of the task. The researchers found similar results for “joy,” as well as a decrease in “tiredness” compared to eating nothing. Macht and Dettmer don’t discuss it, but I wonder if the increase in mood 90 minutes after eating nothing is due to the fact that participants will again be able to eat something!
Unfortunately, eating chocolate isn’t all good news. Take a look at this chart of “guilt”:
As you can see, guilt takes a dramatic leap immediately after consuming chocolate, while eating an apple or nothing shows no significant effects, even though these volunteers were all in the normal weight range for their height. Fortunately, with time, these feelings of guilt do appear to dissipate (from my anecdotal example, by the age of 39, they dissipate completely!).
So are the elevated feelings of joy and a better mood from chocolate responsible for improving my ability to write Cognitive Daily posts? Unfortunately, that experiment hasn’t been conducted yet. However, if any taste researchers need volunteer participants, I’ll be first in line!
Macht, M., & Dettmer, D. (2006). Everyday mood and emotions after eating a chocolate bar or an apple. Appetite, 46, 332-336.