author describing the hazardous physical and
behavioral effects of excessive caffeine intake.
Recording. Each day during treatment, the
subjects recorded the number of cups of coffee
and other caffeine-containing beverages they
drank. Their recording sheets contained a list of
the caffeine value (mg) for each beverage (see
Footnote 1). After consuming a beverage, the
subject recorded its caffeine content, the activity
associated with drinking the beverage, and calculated
the total intake of caffeine to that moment.
(The requirement of keeping a daily
running account of total caffeine intake had
been specified in the contract.) At the end of
each day, they plotted their total caffeine intake,
caffeine intake of coffee, number of cups of all
caffeine-containing beverages, and the number
of cups of coffee on graphs that had been provided
at the beginning of treatment. On the
total caffeine intake graph, a criterion line was
drawn across each treatment phase that indicated
the maximum mg of caffeine that could
be consumed per day. This criterion level of mg
of caffeine was written also on the daily recording
sheets. At the end of each treatment
phase, the recording sheets were collected and
examined for correctness. At this time, the subjects
were instructed about the next phase and
were given the money that they had earned.