Psychological Science

The Need for Psychological Science

The Limits of Intuition Hindsight Bias

We tend to believe, after learning an outcome, that we would have foreseen it

the “I-knew-it-all-along” phenomenon Overconfidence

We tend to think we know more than we do Heuristics

A “rule of thumb” problem solving technique Confirmation Bias

Our tendency to seek out information that confirms our previous beliefs and to ignore information that refutes them.

The Scientific Attitude

Critical Thinking thinking that does not blindly accept

arguments and conclusions examines assumptions discerns hidden values evaluates evidence

How do we know what we know?

How do you know that George Washington was the first President of the United States?

How do you know that you really have a stomach?

What makes you sure the sun will rise tomorrow?

How do you know the color of the shirt you are wearing?

How can you be sure there aren’t little creatures inside a computer that make it work?

How do we know what we know?

Authority – we take the word of an expert Reason – deductive an inductive thinking

to arrive at a conclusion Observation – your own experience All three ways of knowing are used by

scientists, but observation must be the basis for knowledge that is scientific

The Scientific Method

Theory an explanation using an integrated set of

principles that organizes and predicts observations

Usually a statement about relationship between two variables

Hypothesis a testable prediction often implied by a theory

The Scientific Method

The Scientific Method

Replication repeating the essence of a research

study to see whether the basic finding generalizes to other participants and circumstances

usually with different participants in different situations

Replication is made possible by Operational Definitions

The Scientific Method

Operational Definition a statement of procedures (operations)

used to define research variables Example-

intelligence may be operationally defined as what an intelligence test measures

Flaws in Surveys What are some of

the flaws that you can think of with surveys? Wording Audience Order Who is asking?

Flaws in Surveys Wording:

How can the wording of a survey influence the responses given?

“Sex” vs. “Relations”

“Hate” vs. “Dislike”

“Love” vs. “Like”

Flaws in Surveys Audience:

How can the audience to which the survey is given influence the responses?

Location and topic How are the

questions asked?

Flaws in Surveys Order:

How can the order in which the questions are asked influence the responses?

- 1.) Do you think the actions of the Sept. 11th attacks were wrong?

- 2.) Does it anger you that American soldiers are dying in Iraq?

- 3.) Do you think people in the Middle East are generally violent?

Random Samples

Why is it important to have random samples in survey research? Some fun statistics:

68% of people roll toilet paper over the spool 79% squeeze toothpaste from the top 7% look behind the shower curtain when using someone

else’s bathroom 80% of people eat corn on the cob in circles instead of rows 10% of people have seen a ghost 7% of people have flossed their teeth with their own hair

Random Samples What was wrong

with each one of those statistics? Those responses

were the results of only about 7,000 people out of 25,000 surveyed.

Random Samples Acquiring random

samples is not as easy as it looks, but is very important to at least “attempt” to do with any survey. American Idol (ughhh)

How are their “phone or text in” surveys not as random as they seem?

You better feel strong enough about your vote to want to pay $1.00 or whatever it is.

Random Samples

Obtaining random samples for any purpose is difficult. The government has had no more success than the private sector. The 1970 lottery to determine the order of the military

draft was almost certainly unfair. The 31 capsules for January were placed in the bin

first, then the 29 for February, and so on until the 31 for the next December.

What do you think happened when the bin was not turned enough?

The December Birthdays were drawn much earlier.

Correlation and Cause/Effect Misinterpretations

What is Correlation? Seriously, who here knows?

RELATIONSHIP….Not cause! Correlation should not be interpreted as a

cause and effect. It is very easy to misinterpret correlation

studies as a cause an effect issue, but this is not accurate.

Pellagra example.

Correlation and Cause/Effect Misinterpretations

A Story;

In the early twentieth century, thousands of Americans in the South died from Pellagra, a disease marked by dizziness, lethargy, running sores, and vomiting.

Correlation and Cause/Effect Misinterpretations

Finding that families struck with the disease often had poor plumbing and sewage, many physicians concluded that pellagra was transmitted by poor sanitary conditions.

In contrast, Surgeon General Joseph Goldberger thought that the illness was caused by an inadequate diet.

Correlation and Cause/Effect Misinterpretations

He felt that the correlation between sewage conditions and pellagra did not reflect a casual relationship, but that the correlation arose because the economically disadvantaged were likely to have poor diets, as well as poor plumbing.

So, how was the controversy resolved?

Correlation and Cause/Effect Misinterpretations

Well, the answer demonstrates the importance of the scientific method.

To prove he was right, Goldberger not only had himself injected with the blood of a victim with sores all over his body, he found a victim with diarrhea and….ate his excrement!

He did NOT come down with pellagra!

Correlation and Cause/Effect Misinterpretations

To further make his case, Goldberger asked two groups from a Mississippi state prison farm to volunteer for an experiment. One group was given a high carbohydrate, low protein diet that Goldberger suspected to be the culprit, while the other received a balanced diet. Within months, the first group was ravaged by pellagra, while the second showed no signs of the disease.