SBI 4U
Panayiotou
Page 1
PHYSIOLOGICAL EFFECTS OF SMALL DOSES OF
CAFFEINE ON HUMAN SUBJECTS
IMPORTANT NOTES
Please do not consume any caffeine on the day we collect data for this lab. Please
do not wear hosiery or tights to lab. You will be given a beverage to consume
prior to coming to the lab that day at a given time. You do not have be a
participant of this experiment, but please notify me prior to the day if you do not
want to be a participant.
BACKGROUND
Many people claim that they cannot start their day or stay awake driving long distances
without the caffeine in a cup of coffee. Although large doses of caffeine can affect many
aspects of physiology such as nerve, muscle, gastric, and kidney function, how much
does the small dose of caffeine found in a single cup of strong coffee/pop influence a
person's physiology? Do the caffeine "buzzes" people report actually result from
measurable effects of the coffee on their physiology, or do they represent a placebo
effect? A placebo effect is a change in an individual's physiology induced by that
person's expectation of the change.
PROCEDURE
1. Design an experiment that allows you to investigate the effect of the dose of caffeine
found in a single cup of strong coffee/pop on the physiological variable of your choice.
Use of the biological literature on the physiological effects of caffeine may help you
identify potential variables. Schedule your discussion early enough so you can consult
with me regarding whether we have the ability to measure the physiological variables
that interest you. Please be aware that because of health concerns we cannot measure
any variable that requires the collection of bodily fluids or tissues.
2. . Remember to make a prediction BEFORE you begin.
3. You will have the following materials at your disposal (familiarize yourself with the
equipment first)
Beverage - caffeinated and decaffeinated
Styrofoam cups
Blood pressure equipment
Devices to measure reaction time to visual or auditory stimuli
Probes?
SBI 4U
Panayiotou
Page 2
DESIGN SUGGESTIONS

Stay focused on the problem when designing your study.
Control for the possible existence of a placebo effect. How many treatment and
control groups will you use? What will be the sample size for each group? How will
you execute the experiment? If caffeine affects your physiological variable, how
should the means for your treatment and control groups compare?

Since people in the lab will probably vary greatly in their baseline measurements for
many physiological variables, most researchers use each individual's change in the
physiological measurement (e.g., post coffee heart rate minus pre coffee heart rate)
as the dependent variable in these types of studies. By using the change in, say,
heart rate for each subject as your dependent variable rather than simply that
person's post-coffee consumption heart rate you often reduce the variance in the
data. Also think about the placebo effect.

Allow at least 30 min between the ingestion of the caffeinated beverage or control
solutions and the post beverage measurements.

Design a data sheet.
ASSESSMENT (30 marks)
COMPONENT
DESCRIPTION
MARKS
Purpose
Describe the reason for the investigation.
1
Hypothesis
It should show a cause and effect relationship. Give some
reasoning behind it.
2
Materials
List in column of all material used
1
Procedure
In paragraph format, outline specifically what was done in
the investigation and what type of data was collected.
Remember someone else should be able to repeat your
experiment based on your description. Your lab report
should be in past passive tense
10
Observations
Data Tables and appropriate graph(s) depicting the
relationship between your independent and dependent
variables. Label and name your graph(s) appropriately.
ONLY computer generated or graphs on graph paper are
allowed. You may also include qualitative type of
observations.
5
Analysis
In paragraph form, discuss your results and the reasons
behind the results. Discuss how caffeine works in the body
and relate it to your results. Relate results back to your
hypothesis. Discuss the reliability and conclusiveness of
your results. Analyze your experimental design and suggest
methods for improvement. Discuss the “next step” in the
investigation. Discuss the significance (application) of this
research to society.
10
Conclusion
In a brief statement discuss the results of this lab.
1
SBI 4U
Panayiotou
Page 3