Psych 101: Introductory Psychology Lab

Week 2 Highlights

Experimental Research Methods- The basics

• Experiment
• Hypothesis
• Operationalized variables

Measuring Motor Learning

• Mirror Tracing
• Neuropsychology Clinical & Experimental Implications

Mirror Tracing Task

• What might affect performance on this task? Distraction
• Form a hypothesis that can be tested&endash;

Term	Definition	Application
Independent variable	Condition(s) manipulated by the experimenter.	Presenting trials with distraction and without.
Controlled variable	Conditions that are kept constant, across trials and from subject to subject. Controlling variables isolate the independent variable that's manipulated.	Establishing parameters (trial and inter-trial interval duration, type of distracter and task, number of trials, practice period, etc.)
Dependent variable	What is measured (by quantifiable means) e.g., a score, time to complete, number errors/correct.	Composite score&endash; takes into account time & distance.
Confounding variables	Uncontrolled variables that may combine with the effects of the independent variable to produce the dependent variable. Well-designed experiments attempt to avoid confounding variables e.g., by using counterbalanced designs.	Progressive errors- fatigue, practice, random error.

Term	Definition	Application
Within subjects	The subjects receive all the conditions, thus serving as their own "control" or referent group.
Between subjects	Subjects are divided into groups- either by a characteristic (e.g., gender, old/young), or by the conditions they undergo (e.g., distracted or quiet gr.)	How could our mirror tracing experiment be modified for a between subjects design? Is this a good idea? Why or why not?
Counter- balancing	Arranging the presentation of trials such that the effect of progressive error in one condition cancels out the progressive error in another condition.	For the mirror tracing experiment, a within subjects, ABBA counterbalanced design was chosen. You may include a 1 sentence explanation for this choice in your Methods section.
Confounding variables	Uncontrolled variables that may combine with the effects of the independent variable to produce the dependent variable. Well-designed experiments attempt to avoid confounding variables e.g., by using counterbalanced designs.

1. Practice the task using these parameters

• Track- Star
• Speed- 5
• Direction- Counterclockwise, Reversed
• Show Tone
• Show Trial #
• Trials- 3
• Duration- 20 secs
• Inter-Trial Interval 10 secs

1. Run the experiment
2. Choose a partner
3. Determine your parameters

• Why are you choosing the parameters at those particular levels?
• You must complete 12 counterbalanced trials.

1. Determine your distractor
2. Determine who will be the Experimenter and who will be the Participant
3. Set-up and run the experiment
4. Record the time & distance score for each trial on Table 2-1 on page 41.
5. Calculate the means for each condition.

Assignment: Write a methods section for the experiment. Include table 2-1.

Last update: 31 March 1998