Copyright © Allyn & Bacon 2007

The Monty Hall Problem I present three envelopes labeled A, B and C. One of them contains a dollar. The contestant, Sally, chooses envelope A. I then tell the contestant that the dollar was NOT in envelope B. Then I offer Sally a chance to switch to envelope C. Should she? Copyright © Allyn & Bacon 2007

Did We Know It All Along? Hindsight Bias
“I knew it all along”

The Scientific Attitude: Curious, Skeptical and Humble
Three main components Curious eagerness Skeptically scrutinize competing ideas Open-minded humility before nature Hindsight bias, overconfidence and our tendency to perceive patters in random events often lead us to overestimate our intuition.

Types of Studies Case study: one person is studied in depth in the hope of revealing universal principles. Anecdotes don’t prove anything, but suggest further study Naturalistic observation: observing and recording behavior in naturally occurring situations Describes behavior; does not explain behavior What we did with our experiment on fidgets Copyright © Allyn & Bacon 2007

Other types of research
Survey [asking questions] Must make sure questions are worded accurately 27% approved of “government censorship” of television, but 66% approved of “more restrictions on what is shown on television” Must make sure population is randomly sampled People may answer unreliably Copyright © Allyn & Bacon 2007

Observational studies
Longitudinal study: a sample of the population is studied at intervals to examine changes/effects— often many decades (difficult and time consuming) Longitudinal studies allow scientists to distinguish between short-term and long-term phenomena, such as poverty. If the poverty rate is 20% at a point in time, this may mean that 20% of the population is always poor, or that the whole population experiences poverty for 20% of the time. It is not possible to conclude which of these possibilities is the case using one-off cross-sectional studies. See the 56UP trailer here Read about the amazing Harvard study here Copyright © Allyn & Bacon 2007

Observational studies
Cross-sectional: Sampling groups at different points along a development path e.g. Surveying people every 10 years is ____________. Surveying 20 year olds, 30 year olds and 40 year olds at the same time is ____________. Cohort Sequential: a combination of both longitudinal and cross-sectional Copyright © Allyn & Bacon 2007

Other types of studies Non-experimental methods include: Correlational studies How well does A predict B…and vice versa measures whether factors vary together Does NOT prove cause and effect Question: there is a correlation between depression and low self-esteem. Does depression cause low self esteem? Copyright © Allyn & Bacon 2007

Correlations: A relationship between Two Variables
Correlation– A relationship between two variables, in which changes in one variable are reflected in changes in the other variable Correlation coefficient–(r) A number between -1 and +1 expressing the degree of relationship between two variables. r Copyright © Allyn & Bacon 2007

Correlation

Illusory correlations
Spurious correlations Copyright © Allyn & Bacon 2007

What type of studies are these?
Researchers study a teen with schizophrenia to determine what sort of difficulties people like him have. Researchers follow 20 graduates of LC, taking measurements of mental health every five years. Researchers ask 300 randomly selected people how they cope with anxiety. Researchers observe and describe behavior of music fans waiting in line for entrance to a concert. Researchers test to see if body mass index and happiness are connected. Researchers randomly select 150 people to test for anxiety. Using random assignment, researchers teach 50 people relaxation techniques, teach 50 people fake relaxation techniques, and do nothing to 50 people, then test all the subjects to see if relaxation techniques work. Copyright © Allyn & Bacon 2007

How Do Psychologists Develop New Knowledge?
Empirical investigation – A reliance on sensory experience and observation as research data Scientific method – A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments Copyright © Allyn & Bacon 2007 18

The Five Steps of the Scientific Method
Developing a hypothesis Hypothesis – A statement predicting the outcome of a scientific study—must be falsifiable Performing a controlled test Gathering objective data Analyzing the results Operational definitions – a statement of how a researcher will measure behaviors—makes behavior measurable Publishing, criticizing, and replicating the results Copyright © Allyn & Bacon 2007 19

Developing a hypothesis Independent variable – The variable manipulated by the experimenter Performing a controlled test Gathering objective data Controlled variables – Variables that are held constant in order to analyze the relationship between other variables without interference. Analyzing the results Publishing, criticizing, and replicating the results Copyright © Allyn & Bacon 2007 19

Things a controlled experiment must have
Randomization: Random sampling: subjects are chosen at random from the population (population: ALL people in a group being studied) [avoids sampling bias] Random assignment: subjects are assigned to experimental (receives treatment), control (receives no treatment) and placebo (receives inert treatment) group randomly Placebo Effect: experimental results caused by expectation alone; any effect on behavior caused by an inert substance, which the recipient assumes is an active agent. See the placebo effect in action (23:40) Copyright © Allyn & Bacon 2007

Things a controlled test must have
Blind experiment: information is withheld from subject Double blind: information is withheld from subject and experimenter Control of confounding variables: things that have an effect on the dependent variable, but were not taken into account in the experimental design. Researchers MUST make every attempt to control them. Copyright © Allyn & Bacon 2007

Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Dependent variable – The measured outcome of a study Publishing, criticizing, and replicating the results Copyright © Allyn & Bacon 2007 19

Hypothesis: Excessive noise causes acute anxiety How do we design this experiment? What is the independent variable? The dependent variable? Our operational definitions? What are some confounding variables? Copyright © Allyn & Bacon 2007

Developing a hypothesis Performing a controlled test Gathering objective data Based on statistical analyses of results, the hypothesis is accepted or rejected Analyzing the results Publishing, criticizing, and replicating the results Copyright © Allyn & Bacon 2007 19

Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Research must withstand the scrutiny of the scientific community Publishing, criticizing, and replicating the results Copyright © Allyn & Bacon 2007 19

What type of studies are these?
Researchers study a teen with schizophrenia to determine what sort of difficulties people like him have. Researchers follow 20 graduates of LC, taking measurements of mental health every five years. Researchers ask 300 randomly selected people how they cope with anxiety. Researchers observe and describe behavior of music fans waiting in line for entrance to a concert. Researchers test to see if body mass index and happiness are connected. Researchers randomly select 150 people to test for anxiety. Using random assignment, researchers teach 50 people relaxation techniques, teach 50 people fake relaxation techniques, and do nothing to 50 people, then test all the subjects to see if relaxation techniques work. Copyright © Allyn & Bacon 2007

Review What do you think the hypothesis of the fidget study was? What was the IV? DV? What were possible confounding variables? eyes closed/eyes open; lack of training; imprecision of counting How could I have improved this study? -operational definitions -videotape Copyright © Allyn & Bacon 2007

Types of Psychological Research
Experiment: an investigator manipulates one factor (IV) to observe the effect on another factor (DV). In experiments, the researcher controls all the conditions and manipulates the conditions. Thus, only an experiment can isolate cause and effect Copyright © Allyn & Bacon 2007 24

Organizing the Data First results must be arranged in a chart known as a frequency distribution, which simply shows numerically how frequently items occur. We can convert the data into a bar graph called a histogram Let’s look at a histogram from the survey you submitted—for instance, how many TVs do you have in your house? Copyright © Allyn & Bacon 2007

Describing the Data With Descriptive Statistics
Descriptive statistics include: The range: the difference between the highest and lowest score Measures of Central Tendency The mean: the average; affected by extreme scores The median: the middle score; resistant to extreme scores The mode: the most frequent score Copyright © Allyn & Bacon 2007

Looking at statistical results
Previously we have looked at descriptive statistics. Now let’s look at an inferential statistic. P value: likelihood that results are due to chance. P<.05 is good. Copyright © Allyn & Bacon 2007

Ethics in Research Research psychologists must: Obtain informed consent Outline risks and benefits; must be voluntary Sample informed consent form Protect subjects from harm & discomfort Keep subjects’ identity confidential Fully debrief afterward Copyright © Allyn & Bacon 2007 27

Copyright © Allyn & Bacon 2007

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