Behavioral Research Chapter 9 “Conducting the Experiment”

. Conducting the Experiment Selecting Research Participants –Probability vs. non probability sampling –Sample Size

Manipulating the Independent Variable Construct an operational definition of the variable of interest. Set the Stage for introducing the independent and dependent variable. –Obtain informed consent –Provide the rationale for why the experiment is being conducted –May have to use deception which carries an obligation for a debrief at the conclusion of the experiment.

Types of Manipulations Straightforward manipulations Staged manipulations –Used for two reasons: »Researcher may be trying to create some physiological state in the participant, such as anger, or temporarily lowering self esteem. »May be necessary to simulate some situation that occurs in the real world  confederate  Asch conformity study

Strength of the Manipulation Make the manipulation as strong as possible thus maximizing the difference between the two groups and increasing the chance that the IV will have a statistically significant effect on the dependent variable. Ethical considerations

Measuring the Dependent Variable Three general types: self-report, behavioral, physiological Sensitivity of the Dependent Variable Multiple Measures Cost of Measures Ethics.

Types of Manipulations –Self report- can be used to measure attitudes, liking for someone, judgments about someone’s personality characteristics intended behaviors, emotional states, etc –Behavioral measures: direct observation of behavior Rate-record the number of times the behavior occurs in a given time period Reaction time-how quickly a response occurs after a stimulus Duration-how long the behavior lasts. –Physiological Measures -recordings of responses of the body. Galvanic skin response  measure of general emotional arousal and anxiety by measuring the conductance of the skin which changes when sweating occurs. Electromyogram  measures muscle tension and is used as a measure of tension and stress. Electroencephalogram-measure of electrical activity of brain cells, can be used to record general brain arousal as a response to different activity---especially during sleep Others: heart rate, blood pressure urine and blood analysis, etc.

Sensitivity of the Dependent Variable Measure should be sensitive enough to detect differences between groups Important when measuring human performance –Ceiling effects –Floor effects

Multiple Measures Can strengthen the conclusions Independent variable (e.g. illness or stress) may have an effect on many measurable dependent variables. –Missed work days –Number of doctor visits – Phsyiological measures Order effects may not be feasible due to cost, or ethics.

Additional Characteristics Demand Characteristics Placebo Groups Experimenter Expectations

Additional Considerations Research Proposals Pilot studies Manipulation Checks Debriefing

Analyzing & Interpreting Results Statistical Analysis Communicating Research to others –Professional meetings –Journal articles

Method Section The placement of the Method section is immediately following the Introduction. The title is Method. The first sub heading is participants, left justified and bolded. In this section you will describe your participants as to how many, how recruited, incentive for participation. The second subheading is procedure, also left side justified, and bolded.

Procedures This is a subsection in which you inform the reader of all of the details necessary for another party to replicate your experiment. First, you must obtain informed consent. Second, you need to describe the environment in which the experiment will be run. This should include the set up of the room, the number of researchers needed and any materials.

Procedures (continued) You must specify the testing instrument and scoring. The next subsection is Experimental Design-again left side justified and bolded. This is one sentence, such as the design of the current experiment is a two session repeated measures, post test only. The last section is statistical analysis which will gone over in class.