Psychology Ch.2

Empiricism

Knowledge can be gathered by sensory experience. Like observing listening.

Scientific Method

A procedure for using empirical evidence to establish facts

Theory

A said of statements that are logically related that explain a wide body of data. A web of hypothesis

Hypothesis

A statement that can be tested by experiments or observations usually used in “if then” statement

Operational Definition

A description of a property in measurable terms. Like using IQ score for intelligence

Validity (construct validity)

Does a test/measurement measure what its supposed to measure. Like measuring a finger to test inteligence might be reliable but does not measure intelligence

Reliability

How consistent a test is or how consistent the results are. If its consistent its reliable

Self-Report

A method where people provide subjective information about their own thoughts, feelings, or behaviours, typically from questionnare or interview

Social desirability bias

People tend to give answers that they think will make them look better and more socially desirable in self reports.

Demand characteristics

When people behave in a way they think someone else wants or expects

Naturalistic observation

Gathering information without manipulating people in their natural environments

Observer Bias

The tendency for observers expectations to influence both what they believe and what they observed and what they actually observed

Double-Blind study

When neither the participant or researcher know how their expecated to behave

Population

A complete collection of people

Sample

A group of people from the population

Representative sample

When the sample is representative of the population. If the sample has demographics similar to the population

Random sampling

The population has an equal chance of getting picked in the sample

Stratified sampling

Forcing samples to be representative by being strict of the people you put in the study. Putting the population into distinct groups and randomly picking from each

Frequency distribution

A graphic representation showing the number of times each result or measurement of a property appears

Normal distribution

When the highest frequency of a measurement is in the middle and decreases symmetrically both ways

Mean

The average score but is sensitive to outliers

Median

The value that is in the middle

Mode

The value that is most common or most frequent

Positively skewed

The tail is towards the positive side. Outliers is the tail

Negatively skewed

The tail is towards the negative side. Outliers is the tails

Range

The highest score minus the smallest

Standard deviation

A value that describes how each of the values in a frequency distribution differs form the mean

Variable

A property that can have more than one value.

Correlation

When two variable tend to change together

Positive correlation

When one variable increases the other also increases

Negative correlation

When one variable increases the other decreases

Correlation does not imply causation

Correlation does not mean they cause each other. There are three possibilites. 1. A causes B 2. B causes A 3. C (something you did not measure) causes A and B. But you dont know which is the causation just becasue theyre correlated.

Experiment

Used to find causation.

1. Get sample

2. Randomly assign to two different groups

3. manipulate group 1 and dont do anything to group 2.

4. Measure something in both groups

Manipulation

Being able to control a variable and its value

Random Assignment

Where people in the sample are placed into different groups everyone has an equal chance of getting into each group

Independent variable

Variable manipulated in the experiment

Dependent variable

The variable that is measured in the experiment

Between-subjects experiment

Randomly assign people to two or more groups. One group gets one level of the independent variable the other group gets another level of the independent variable

Within-subjects experiment

Take one group of people and give them BOTH levels of the independent variable

Counterbalancing

In within subjects experiment randomize the order in which the levels of independent variable will be given. Half the people do A-B the other half do B-A.

Internal Validity

Within your experiment can you be confident that the change in the independent variable CAUSED a change in the dependent variable and not other variables

Confounding variable

Anything different between the two groups in your experiment OTHER than the independent variable. So everything should be the same in both groups except the independent.

External Validity

Will the result GENERALIZE outside of your experiment. So will the sample results apply to population

Case method/case study

A procedure for gathering scientific information by studying a single individual

Replication

An experiment that uses the same procedure but with a new sample from the same population and gets the same pattern its been replicated

P-value

The probability of getting your results IF there is no difference in the population.

Low value. Means there is evidence that there is a difference in population. The probability value is sooo low that is should be extremely rare to happen but you just observed it. Showing there is evidence maybe there is a difference

High value. Means there is not enough evidence that there is difference in population. Since the probability to get your result is so high there’s no difference

You genuerally want to have a low p value to remove your null hypothesis

Statistical significance

If the p-value is less than a cutoff usually 0.05 than the difference is real. However we can be wrong when doing so.

Cross-cultural replication

Doing same psychology studies in other cultures besides WEIRD since most has been done in WEIRD.

WEIRD countries

Are Western, Educated, Industrialized, Rich, Democracies. Canada, US, Western Europe, Australia, New Zealand

Muller-Lyer illusion

A line looks bigger than the other when their both the same due to the angles. Cross culture perception people would see that both are same lines but due to the culture veiwing that angle alot it seems different

Type 1 Error

When concluding there is a real difference in population from the p-value when in fact there isn’t a difference.

Type 2 Error

When concluding there is no difference but when in fact there is a difference

Skepticism

Questioning claims and not accepting them as true until there is solid scientific evidence

Informed consent

You have to tell participants about what the study will involve, and ask them to give consent through a form.

Deception

Deceiving the participants by giving incomplete information to avoid them from knowing what the study is about

Debfriefing

A verbal description of what the study was actually about and the purpose