The Experiment Only research method capable of showing cause and effect

2 Experimental Research Explores cause and effect relationships. Eating too many bananas causes Aggressive behavior

3 Steps in Designing an Experiment 1.Question 2.State Hypothesis 3.Pick Population: Random Selection then Random Assignment. 4.Operationalize the Variables 5.Identify Independent and Dependent Variables. 6.Look for Extraneous Variables 7.Type of Experiment: Blind, Double Blind etc.. 8.Gather Data 9.Analyze Results

Hypothesis A statement about the relationship between two or more variables Must be testable and refutable Instead of proving the hypothesis, science usually tries to disprove a null hypothesis. Null Hypothesis (H 0 ): opposite of hypothesis Hypothesis Example: H 1 : Gender has an effect on spatial ability H 0 : Gender does not have an effect on spatial ability

Population – The larger group of people from which a sample is drawn Sample: Representative of the population Two ways to get sample Random: Every member of the pop has = chance Stratified: Sample is put together by picking a group statistically equal to the population

6 Assigning participants to experimental and control conditions by random assignment minimizes pre-existing differences between the two groups. Random Assignment

Variables Independent Variable (I.V.): manipulated by experimenter Dependent Variable (D.V.): MEASURED variable influenced by independent Operational definition Confounding/extraneous variables

8 An Independent Variable is a factor manipulated by the experimenter. The effect of the independent variable is the focus of the study. For example, when examining the effects of breast feeding upon intelligence, breast feeding is the independent variable. Independent Variable

9 A Dependent Variable is a factor that may change in response to an independent variable. In psychology, it is usually a behavior or a mental process. For example, in our study on the effect of breast feeding upon intelligence, intelligence is the dependent variable. Dependent Variable

Control Measures Single-Blind: subject unaware of assignment Double-Blind: subject and experimenter unaware of placement

11 Experimental Vocabulary Independent Variable: factor that is manipulated Dependent Variable: factor that is measured Extraneous Variables: factors that effect DV, that are not IV. Experimental Group: Group exposed to IV Control Group: Group not exposed to IV Placebo: inert substance that is in place of IV in Control Group

12 Analyze Results Use measures of central tendency (mean, median and mode). Use measures of variation (range and standard deviation).

13 Experimentation A summary of steps during experimentation.

Flaws in Research Sampling Bias Overgeneralization Placebo effect Hawthorne/Barnum effect Demand Characteristics Experimenter Bias

APA Ethical Guidelines for Human Research All research goes before an institution review board (IRB) for approval Research involving humans must meet the following standards: 1. Informed Consent-participants must know that they are involved in research and give their consent or permission 2. Deception-if the participants are deceived in any way about the nature of the study the participants must be debriefed after the study is over 3. Coercion-participants cannot be coerced in any way to participate in the study. 4. Anonymity/Confidentiality -the identities and actions of participants must not be revealed in anyway by the researcher. 5. Risk -participants cannot be placed at significant mental or physical risk. DO NO HARM 6. Debriefing Procedures-participants must be told of the purpose of the study and provided with ways to contact the researchers about the results after the study is complete 15

Ethics in Research with Animals 1. (Purpose) They must have a clear scientific purpose. The research must answer a specific, important scientific question. Animals are chosen because they are best-suited to answer the question at hand. 2. (Care) They must care for and house animals in a humane way. 3. (Acquiring animals) They must acquire animal subjects legally. Animals must be purchased from accredited companies. If wild Animals must be used, they need to be trapped in a humane way. 4. (Suffering aka DO NO HARM) They must design experimental procedures that employ the least amount of suffering feasible. 5. (Supervision) A trained psychologist must supervise all research with animals