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Two types of empirical questions
• Descriptive– This kind of empirical question requires a
researcher to describe some aspect of behavior– For example, a researcher might ask, What are
people’s attitudes toward the homeless?
• Causal– This type of empirical question requires a
researcher to determine what causes something to happen
– For example, a researcher might ask, Does stress cause people to have road rage?
Our studies• We want to know whether or not verbal
estimate-based depth perception training benefits subsequent performance on verbal and active tasks?
• In other words, we want to know whether or not such training causes better performance later on
Question• How do you determine that one
thing caused something else to happen?
• For example, how could we determine that a new training simulation improved performance?
A simple logical method1. Collect data about current behavior2. Change the suspected cause3. Do not change anything else4. Collect data about subsequent
behavior5. Compare data collected before and
after the change was made
Example1. Pre-test painting ability2. Provide training via simulator3. Do not change anything else4. Post-test painting ability5. Compare pre and post-test data
Complications• The logical process outlined earlier
is intuitive and straightforward
• When studying behavior, however, several issues could occur that would complicate the interpretation of the data
Potential Complications 1 & 2• Something other than the
suspected cause changes– Something inside the participants
changes• This is known as a maturation problem
– Something outside the participants changes• This is known as a history problem
Maturation1. Pre-test painting ability
– The participant warmed up during the pre-test
2. Provide training via simulator3. Do not change anything else4. Post-test painting ability5. Compare pre and post-test data
– Is the difference due to training or warm-up?
History1. Pre-test painting ability2. Provide training via simulator
– The simulator technician provides some advice
3. Do not change anything else4. Post-test painting ability5. Compare pre and post-test data
– Is the difference due to training or advice?
Potential Complication 3• The initial data collection may bias
participants– This is known as a testing problem
Testing1. Pre-test painting ability
– Certain aspects of painting are assessed
2. Provide training via simulator– Participants work hard on aspects of painting that will
be assessed
3. Do not change anything else4. Post-test painting ability5. Compare pre and post-test data
– Is the difference due to training or bias?
Potential Complication 4• How one collects the Pre-Test data
may differ from how the Post-Test data are collected– This is known as a instrumentation
problem
Instrumentation1. Pre-test painting ability
– Test involves a door panel
2. Provide training via simulator3. Do not change anything else4. Post-test painting ability
– Test involves a trunk lid
5. Compare pre and post-test data– Is the difference due to training or tasks?
Potential Complication 5• Sometimes the Pre-Test scores are
extreme, so it is likely that Post-Test scores will be different, no matter what– This is known as a regression problem
Regression1. Pre-test painting ability
– A number of participants score abnormally low
2. Provide training via simulator3. Do not change anything else4. Post-test painting ability
– Those low scoring participants score more average, while others stay the same
5. Compare pre and post-test data– Is the difference due to training or abnormal scores?
Solution• There is a simple way to capture these
issues, if they occur– Include a control group– If Pre and Post-Test scores differ for both
the experimental and control groups, then it is likely that the study was affected by one of these problems• This is known as having a confound in a study
A more complex method1. Collect data about current behavior2a. Experimental group - Change the suspected
cause2b. Control group - Don’t change the suspected
cause3. Don’t change anything else4. Collect data about subsequent behavior5. Compare data collected before and after the
change was made
Example1. Pre-test painting ability2. Provide training
– Via simulator (Experimental group)– Via standard method (Control group)
3. Don’t change anything else4. Post-test painting ability5. Compare pre and post-test data
Our studies• Experimental group
– Pre-Test, Verbal Training w/ Feedback, Post-Test
• Control group– Pre-Test, Verbal Training w/o Feedback,
Post-Test