Psychology as a Science

Scientific Method  How is it used in psychology? It helps us separate true claims about the world from mere opinion It helps us reject false claims and preserve only those claims that we know to be solidly established Anecdotal evidence: evidence that has been informally collected and reported.

- Testable Hypothesis: (we ask)  1. We make specific predictions about what we will find, given a particular set of circumstances.  2. Check data that is already available to us.  Ex. A previous similar study  1. Hypothesis – specific enough so we can know with certainty what facts would confirm the hypothesis and what facts would disconfirm it. (Try to avoid open-end questions)

Our example  College freshmen will feel more attractive after being exposed to several subliminal messages during their first semester of college.

Adding your variables (we identify)  Dependent Variable: the variable that “depends” on other factors (results, outcome)  Independent Variable: variable whose effects want to be examined (what we manipulate, change, or differ in an experiment)  Ex. Study with subliminal messages and attractiveness  -Dependent variable: level of attractiveness claimed  -Independent variable: using or not using subliminal messages in self-help recording with subliminal messages.

Designing a persuasive experiment (we choose) -Who will participate in the study? Matching participants in every degree except the experimental manipulation e.x. same type of music, same time between the time they stop hearing the music and their interview, same information -This leads the two groups to have similar expectations about the procedure

Random Sampling

Creating the design (We Assign)  Control group: a group that provides a basis for comparison, allowing the investigator to assess the effects of the experimental manipulation  e.x. no subliminal messages.  Experimental group: the group that takes part in the investigation  e.x. subliminal messages.  Now we ask? Was it really the subliminal messages?

We continue to (assign) Random Assignments  Experiment and Control group must be (almost) identical to each other Ex- All members who were first willing to participate Ex- Testing and Classrooms  With-in Subject vs. Between Subjects Comparison  Within- same people for control and experimental  Between- different groups

We manipulate  Researchers will now manipulate the independent variable by administering the treatment. (one or two levels) example: Experimental group will listen to subliminal messages as they listen to their C.D.  Double-blind design  Placebos

We measure  Researchers will give college freshmen weekly surveys to check their levels of attractiveness.  Surveys will included questions like On a scale from How ……?

We analyze  Statistical procedures are used to determine whether differences observed in dependent variables (level of attractiveness) are due to independent variables (subliminal messages) or to error of chance occurrence.  “ Researchers compared the effects of subliminal messages on a person’s level of attractiveness. They concluded that, subliminal messages did increase the level of attractiveness in college freshmen.  Significantly means- 95% (or above) likelihood that it was the subliminal messages with caused the increase in self-esteem.

Types of Research  Descriptive  Correlational  Experimental

Descriptive Research  Any research that observes and records.  Does not talk about relationships, it just describes. What is going on in this picture? We cannot say exactly, but we can describe what we see. Thus we have…..

The Case Study  Where one person (or situation) is observed in depth. What are the strengths and weaknesses of using a tragedy like the Columbine School Shootings as a case study?

Naturalistic Observation  Observing and recording behavior in natural environment.  No control- just an observer. What are the benefits and detriments of Naturalistic Observation?

Survey Method: The Bad  Low Response Rate  People Lie or just misinterpret themselves.  Wording Effects How accurate would a survey be about the frequency of diarrhea?

The Survey Method  Used in both descriptional and correlational research.  Use Interview, mail, phone, internet etc…  The Good- cheap, anonymous, diverse population, and easy to get random sampling (a sampling that represents your population you want to study).

Correlational Research  Detects relationships between variables.  Does NOT say that one variable causes another. There is a positive correlation between ice cream and murder rates. Does that mean that ice cream causes murder?

Measured using a correlation coefficient.  A statistical measure of the extent to which two factors relate to one another

How to Read a Correlation Coefficient

Other forms of observation  Longitudinal Method- participants are observed at intervals over an extended period of time.  Snap-Shot Method: participants are observed over a few hours or days.  Cross-Sectional Method: researchers compare the differences and similarities among people in different age groups at a given time.

Experimental Research  Explores cause and effect relationships. Eating too many bananas causes Constipation

Some other factors to consider?  What else to consider in the design?  Demand characteristics  Confirmation Bias  Internal Validity  External Validity A.k.a Ecological Validity  Confounds

 Removing confounds  Confounds- any uncontrolled factors that could influence the comparison between the experimental and control conditions  e.x. Time of day, Age of participants  If confounds are present, the experiment lacks internal validity

Analyze Results Use measures of central tendency Mean: arithmetic average Median: the point that divides the distribution into two halves Mode: occurs most frequently Example:  10 students took a quiz ScoreFrequency

A Skewed Distribution Are the results positively or negatively skewed?

Analyze Results  Use measures of variation  Range: the highest score minus the lowest  Variance:  V= Σ (score-M)² Σ= Sum of all N N= number of scores Standard Deviation: SD= √V

V= 44/10 = 4.4 SD= ~ 2.1 ScoreScore-Mean (Score-Mean)² 88-8 =00 ²= =33 ²=9 66-8=-2(-2) ²=4 77-8= -1(-1) ²=1 55-8= -3(-3) ²=9 99-8= 1 1 ²= = -3(-3) ²= = 1 1 ²=1 99-8= 1 1 ²= =3 3 ²=9 Sum=44

Example Score Score- Mean (Score-Mean) ²

Standard Scores (z-scores)  z= (score-M) SD

Ethics  The external validity (ecological validity) of an investigation depends on the relationship between a study and it’s real-world context.  This requires us to study real people and real animals.  Demands that psychological research be conducted ethically.

Important Ethical Codes from APA (2002)  3.10: Informed Consent  4.01: Maintaining Confidentiality  4.02: Discussing the limits of Confidentiality  8.07: Deception in Research  8.08: Debriefing  8.09: Humane care and use of animals in research.  8.10: Reporting Research Results