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OVERVIEW
The “experiment” is the most powerful analytical tool used in science。 Cause…effect relationships can be
established only using well…controlled experiments。 Psychologists employ this tool in the investigation of
virtually all aspects of behavior； including perception； learning； memory； cognition； motivation；
physiological processes； sensory processes； social behavior； development； and therapeutic procedures。
While the specific details of the methodology vary within each of these areas of investigation； the logic of
experimentation is essentially the same。
The following classroom demonstration and discussion should help elucidate the need for； and logic of；
experimental methods in the study of behavior。
GENERAL INTRODUCTION
You （the instructor） are to role…play as seriously as you can a biased…sexist orientation in the attempt to
confirm “what you already believe is true”； namely； that members of your sex are faster reactors than those
of the opposite sex。 You will violate a series of experimental controls to prove your point。 The class has to
catch you in the act。
PROCEDURE
Materials
Reaction…time device constructed from light cardboard （see template）。
Instructions
1。 Propose a hypothesis： “Males react faster than females” （if you are male）； or “Females react faster
than males” （if you are female）。 This will usually draw protests from the hypothesized “slower”
sex。
2。 Define reaction time： the time interval between stimulus presentation and a subject’s reaction。
Using our reaction time meter； it is converted into centimeters of distance between the signal
“Drop” and the subject’s reaction of stopping the falling reaction time meter。
3 。 Select a student of the sex hypothesized as slower。 Ask the student to e to the front of the room
and stand with his or her hand about even with the tip of the meter； with the thumb and forefinger
about two inches apart。 Then； without explanation or warning； drop the meter between the
subject’s fingers。 The subject will probably catch it。 Record the reading； measuring from the top of
the thumb。 Reaction time is measured in centimeters here rather than in seconds。 Give only one
trial。 Write the subject’s score on the board。
4。 Then； ask for a volunteer of the opposite sex。 Have this student e to the front of the room； sit
down； relax； and tell you his or her preferred hand。 Then define the task： to stop the meter as soon
as possible when it is dropped after the signal “Drop” is given。 Hold the meter so that the point is
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two inches above the student’s fingers （instead of even with them）。 Give the subject two practice
trials and a verbal warning signal of “Ready。 ” Then give two test trials and record only the fastest
one。 Then announce that the “obvious” conclusion has been confirmed。
5。 At this point； the “losing sex” will protest； pointing out some of the biases you introduced。 List
them：
。 The first student was selected； while the other volunteered。
。 The first student had to use cognitive processes （since the task wasn’t explained before the
trial）； the second student used simple reaction time。
。 The first student started with the point at fingertip level； the second started with it two
inches above the fingertips （leads to a discussion of accuracy of measurement）。
。 The first student had no “ready” signal； the second did。
。 The first student was standing； the second was sitting。
。 The first student had no practice； the second had practice trials。
6。 Now pretend to run an unbiased test following the class suggestions。 Eliminating all of the
previous biases （by essentially following the procedure for the second subject）； you can still easily
bias the results：
。 By having a fixed foreperiod （warning signal to stimulus onset） for one subject versus a
widely variable one for the other。
。 By using different motivating instructions or feedback （“that wasn’t very good now； was
it？”）。
。 By giving one a motor set （to respond…“get ready to grab it”）； which is faster than a sensory
set （to observe…“watch for it to drop”）。
。 By letting one subject but not the other； see you “prepare” to release the stimulus。
7。 Using any of the above （or in bination）； your hypothesis will again be “proven”。 Have the
students list the biases in this test。 Repeat； using more subtle differences each time。
DISCUSSION
The discussion should lead to the notion of relevant versus irrelevant variables in an experimental
situation。 Relevant variables are those likely to affect the dependent measure （reaction time）； such as those
used to bias this experiment。 Irrelevant variables are those unlikely to affect the results； such as； in this case；
barometric pressure； hair color； socioeconomic level； etc。 This should lead to discussion of the need for
experimental control procedures in order to identify and control relevant variables so that both
experimental conditions are the same in every regard except the independent variable。 Then； any differences
in results can be attributed to the independent variable。
ADDITIONAL RESOURCES
Stanovich； K。E。 （1992）。 How to Think Straight About Psychology。 3rd Ed。 New York： Harper Collins。
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Place Thumb
He re
REACTION TIME
METER
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11
10
9
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3
2
1
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SALIVATING FOR PAVLOV
OBJECTIVES
1。 To have students personally experience what it means to be conditioned to elicit a classical salivary
response。
2。 To perform a simple but effective demonstration of Pavlovian conditioning on the entire class。
3。 To collect conditioned response data on acquisition and extinction that will provide the impetus for
discussing applications and extensions of conditioning principles in everyday life。
OVERVIEW
Many students find the usual discussion of Pavlov’s discovery of the principles of conditioning
uninteresting and without any personal relevance。 Having them salivate–as did Pavlov’s experimental
dogs–may ring a bell for them！
1。 Do not begin by stating the principles of conditioning； but request that the students read Psychology
and Life； chapter 9 before this demonstration。
2。 Do assess the students’ knowledge of the meaning of US…UR； CS…CR； acquisition and extinction。
3。 Perform the following demonstration； which was developed by Dennis and Rosemary Cogan
（Texas Tech University） and described in detail in their article in Teaching of Psychology； 1984； Vol。
11； pp。 170…171。
GENERAL INTRODUCTION
Although conditioning represents one of the most important discoveries in psychology； students fail to
appreciate its significance。 In part； this is due to the description in terms of dogs salivating to bells； hardly
of apparent personal relevance to students。 By making the students salivate to an arbitrary signal （CS） –the
name “Pavlov” –they will be in a better position to appreciate how virtually any neutral stimulus can e
to have the power to elicit powerful biological responses。
Following the demonstration； you should be sure that