Some studies suggest that cigarette smokers attempt to titrate or adjust their nicotine intake to keep the level of nicotine from getting too high or too low; they puff more when nicotine levels are low and less when they are high. The titration theory assumes that the smoker starts smoking when nicotine blood level falls below a certain point in order to avoid withdrawal and stops smoking when blood levels get too high in order to avoid unpleasant toxic effects.

One of the predictions of the nicotine titration hypothesis is that smokers will compensate for low blood nicotine levels by attempting to increase nicotine intake during the early part of a cigarette. There are two ways in which a smoker can increase the amount of nicotine he or she gets from a single cigarette: they can increase the duration of each puff and hold the smoke in their lungs longer, or they can take more frequent puffs on a cigarette. You would predict, then, that early puffs on a cigarette when blood nicotine levels are low would be both more frequent and of longer duration.

For this homework, you will test the nicotine titration hypothesis and its predictions by making some observations of smokers. You'll need a watch with a second hand, a data sheet, and something to write with. It is difficult to measure puff duration in this way, so we'll just concentrate on inter-puff intervals.

First, you need to find some smokers! You can use roommates or friends, but of course, don't tell them the purpose of your study, and don't ask them to smoke just so you can watch them! If you do, they may not behave as they would naturally! Just take advantage of whenever you see a smoker "light up."

What you need to do is to measure the length of time from the lighting of a cigarette to the first puff, and between all successive puffs until the cigarette is stubbed out. If you are collecting data from single individual, you'll need to observe him or her smoking 20 different cigarettes. If you are collecting data on different individuals, be sure to observe a total of 20.

To analyze your data, find the average interpuff interval for each puff over time. Then, plot that average on a graph with the length of time between one puff and the next on the y axis and the puff number on the x axis. Not all cigarettes have the same number of puffs. This can create some difficulties when you get to higher puff numbers, because each data point is based on a decreasing number of observations. For this reason, plot the data ONLY for the number of puffs for which you have complete data--20 samples. For example, if the smallest number of puffs is 8, then plot the average of only the first 8 puffs on all cigarettes.

What do your data suggest? Do interpuff intervals get longer as puff number increases? Do your results support, or fail to support the nicotine titration hypothesis?

If you would like to do a second study, compare smoking in different settings. Are smoking patterns different when the subject is alone compared to with other smokers? Do other activities such as consumption of alcohol alter puffing patterns? Make a prediction about how alcohol consumption or social conditions might alter puff patterns before you make your observations. What did you find? Be sure that you have a comparison group of smokers who are alone or who are not drinking, so you can clearly see any differences there might be between the two groups.

Write up your studies in the form of a proper lab report, with an introduction, methods, results, and discussion section.