Coke contains a stimulant called caffeine. Our hypothesis was that drinking coke will improve our reaction time.

We got into pairs and one person dropped a metre stick for someone else to catch. We wrote down how many centimetres it dropped before it was caught. We did this three times and worked out an average. We were split into two groups and we were then given a cup of coke to drink. This was either normal coke or caffeine free, but we were not told which one. We learnt that when companies test drugs they use dummy tablets called placebos with half the people they test. Our caffeine free coke was like a placebo – our hypothesis was that it would not improve our reaction time, unlike the normal coke, because it does not contain a stimulant.

What we found out

Our result was a little surprising, in that both groups showed an improvement in their reaction times. We did not expect this to happen. However, one group had clearly improved more than the other, and this was the group that had real coke. Our hypothesis that caffeine improves reaction time is therefore likely to be correct.

Possible reasons why the caffeine free group also improved:

1. Other chemicals in this type of coke not present in normal coke boost performance
2. The group improved with practice
3. The group expected to be better and so improved their performance

How could this experiment be improved upon?

Homework – complete sheet on diseases caused by smoking (9Bb9) for tuesday.