psyc 1301 chapter 1

CHAPTER 1What Is Psychology?

Psychology as a SciencePsychology as a Science

What is Psychology?

• Psychology is the scientific study of behavior and mental processes.

• Psychology has often been labeled as a pseudo-science

• Many criticize psychology as a field that only provides answers to obvious questions

You need to hire a contractor for one month. He says that you can start him at 1 penny for his first day, and then double the rate each day following. Should you do it?

Probably not. You’ll owe him $5,368,709.12 for his last day of work. ($10,737,418.24 if it’s a month with 31 days).

Goals of Psychology

• Psychology seeks to:– describe– explain– predict– control behavior and mental processes

What is a Theory?

• A theory allows you to– propose reasons for relationships– derive explanations – make predictions (hypotheses)

• A hypothesis is a testable prediction of a theory.

Evaluating Theories

Useful theories lead to:– Testable hypotheses– Development of solutions to real-world problems

Remember, a theory is a general principle or idea

A hypothesis is a testable prediction of that theory, an if/then statement

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Let’s Consider an Example…

Let’s say I have the general idea that studying highlighted material helps students learn more effectively– This would be my theory…it is a general statement

And let’s say that because of this theory, I predict that experimental subjects who are given highlighted materials to study will perform better on a reading test than students who have non-highlighted material.– This is a hypothesis…it is an extension of my theory that I

can test experimentally

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What Psychologists Do

What Do Psychologists Do?

• Research– Pure research– Applied research

• Practice• Teaching

Fields of Psychology

• Clinical• Counseling• School • Educational• Developmental • Personality• Social• Environmental

• Experimental• Industrial

– Organizational– Human Factors– Consumer

• Health• Sport• Forensic

Where Psychology Comes From: Where Psychology Comes From: A HistoryA HistoryYou should read this section (pg 5-8), but we will not discuss it in class, You should read this section (pg 5-8), but we will not discuss it in class, and it won’t be on your test. We’ll discuss these people and issues as we and it won’t be on your test. We’ll discuss these people and issues as we come to them throughout the course.come to them throughout the course.

How Today’s Psychologists View How Today’s Psychologists View Behavior and Mental ProcessesBehavior and Mental ProcessesSame for this section, pg 9-12Same for this section, pg 9-12

How Psychologists Study How Psychologists Study Behavior and Mental ProcessesBehavior and Mental Processes

Principles of Critical Thinking

• Be skeptical• Insist on evidence• Examine definitions of terms• Examine the assumptions or premises of

arguments• Be cautious in drawing conclusions from

evidence

http://www.youtube.com/watch?v=B8BeGgT1v5MWatch the Hydroxycut commercial with these principles of

critical thinking in mind.

Principles of Critical Thinking (continued)

• Consider alternative interpretations of research evidence

• Do not oversimplify• Do not overgeneralize• Apply critical thinking to all areas of life

The Scientific Method

• Formulate a research question• State the hypothesis• Test the hypothesis• Draw conclusions based on findings• Publish research• Replicate study

Scientific Method

Samples and Populations

• Sample– Segment of population

• Population– Entire group targeted for study

• Representative samples allow generalization of findings

Population—the group you wish to measure and draw a conclusion about (the big jar)

Sample—a subset of the population that is tested (the small jar)

Random sample—each member of the population has an equal chance of being included in the sample

Can we conclude that 40% of marbles throughout the world are blue and the rest of all marbles throughout the world are red? Of course not. Our sample only allows us to draw conclusions about our population.

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Random and Stratified Sampling

• Random sample– Each member of population has equal chance of

selection• Stratified sample

– Subgroups are represented proportionally• Volunteer bias

– Bias represented by studying people who volunteer to participate

Methods of Observation

• Case Study– Gather information about individuals or small

groups– Sometimes used to investigate rarities

• Survey– Used to collect information that cannot be

observed directly

Possible Problems With Surveys

• “Should firearms and cigarettes be banned from college campuses?”– Wording effect– An anti-tobacco lobby would likely favor this

wording. – Tobacco companies would prefer the two

questions asked separately.

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Descriptive Research Methods

Interviews and Questionnaires Advantages

– Results can be affected by wording, content, and interviewer characteristics

– Questionnaires are less expensive and can gather information from large groups quickly

Disadvantages– Costly and time consuming– Faulty information may be gathered– “Social desirability response”– Deliberately provide misleading information

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Methods of Observation

• Naturalistic Observation– Observe subjects in their natural environment– Unobtrusive measure—subjects will behave

more naturally than in laboratory experiments– Does not allow for conclusions about

causation

Correlation

• Mathematical method of determining a relationship between variables

• Correlation– Expresses strength and direction of

relationship between variables• Does not prove cause and effect

Positive and Negative Correlations

Experimental Method

• Demonstrates cause and effect through scientific method.

• In an experiment, the researcher manipulates one variable while attempting to hold all others constant– Independent variable

• What the researcher manipulates

– Dependent variable• What the researcher measures—the data.

Experimental Conditions in the Lang Study

Experimental Method

• Experimental groups– Those receiving vodka

• Control groups– Those not receiving vodka

• Placebos– “Sugar pills” or the tonic water in the Lang Experiment– Important for drug trials

• Double-blind study– Neither the participant nor the researchers know who is receiving a

placebo

Highlighting Example

• Think about the different ways we could test this…• We could compare the grades of students who

highlight and students who don’t…• We could compare the grades of students who

bought new books and who bought used books that were already highlighted

• We could randomly assign some people to receive highlighted material and other people not to

• These are different types of research designs. Think about some of the pros and cons of each of them

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Let’s return to our highlighting example

• Our first option was to compare the grades of students who highlight and those who don’t

• What type of research design is this?• It is correlational• We did not assign them into groups, they chose to

do it or not on their own• Therefore, we cannot conclude that it was the

highlighting that affected their grades• Do students become successful because they

highlight, or do they highlight because they’re successful?

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Let’s return to our highlighting example

• Next, we proposed to compare new and used book performance

• What kind of design was this?• Also a correlation, we’re seeing how test scores vary

as a function of type of book purchased• Again, we can not determine a causal relationship• What are some possible confounding factors here?

– Are there differences between students who buy new and used books?

– No two used books will be highlighted in the same way– What if the former owner highlighted inappropriately. Can

previous highlighting actually become distracting?– While this correlation would be easy enough to run, it

would not clearly tell us anything33

Let’s return to our highlighting example

• Our third idea was to randomly assign some people to receive highlighted material and other people not to

• This is an experiment, and it is the ideal approach to testing our theory.

• By using random assignment, we can assume that our groups are essentially the same– Nuisance variables are randomly distributed

• In this setting, we can make sure everyone receives identical material, identical highlighting, identical study time…we have much more control.

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Let’s return to our highlighting example

• In this experiment, what are the independent and dependent variables?

• Independent: Which group received pre-highlighted reading material

• Dependent: Score on the reading test• Possible confounding variables include:

IQ of the students, motivation of the students to perform, differences in testing times, testing rooms, etc.

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Let’s return to our highlighting example

• In case you were wondering, this experiment has actually been conducted

• As it turns out, the non-highlighted group tends to perform better

• The usefulness of highlighting is not in its assistance with studying later—it is that in order to highlight the main ideas, you have to actively read and think about the material

• You should actually avoid buying pre-highlighted materials whenever possible, because it is almost impossible to read the non-highlighted parts as thoroughly as the highlight parts.

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Ethics of Research with Humans

• Ethical review committee and ethical standards – Promote individual dignity, human welfare and

scientific integrity– Ensure no harm will come to subjects

• Informed consent• Confidentiality• Deception • Debriefing

Ethics of Research with Animals

• Animals are used when research cannot be carried out with humans

• Animals may be harmed, only when:– there is no alternative, and– benefits of the research justify the harm

APPENDIX

Statistics

Statistics

• Numerical facts assembled to provide useful information about measures or scores

• Can be descriptive or inferential

Samples and Populations

Descriptive StatisticsDescriptive Statistics

Descriptive Statistics

• Branch of statistics that provides information about a distribution of scores

Frequency Distribution

Descriptive Statistics

• Frequency distribution– Frequency histogram– Frequency polygon

Measures of Central Tendency

• Mean (average)• Median (mid-most score)• Mode (most frequently occurring score)• Bimodal (two scores occur most frequently)

Bimodal Distribution

Measures of Variability

• Establish the spread of scores• Range (largest score minus smallest score)• Standard deviation

– Most common measure of variability

– Represent the average deviation of any one score from the mean

– Larger SD means higher variability

– Larger SD means that the mean of the score set is less reliable

Measures of Variability

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Standard Deviation

A Bell-Shaped or Normal Curve

The Correlation CoefficientThe Correlation Coefficient

Correlation Coefficient

• Describes a relationship between two variables– Can vary from +1.00 to -1.00– Zero indicates no relationship

• Positive relationship – both variables move in the same direction

• Negative relationship – variables move in the opposite direction

• Correlations do not demonstrate cause and effect

Correlational Relationships, Cause and Effect

Inferential StatisticsInferential Statistics

Inferential Statistics

• Statistics that determine if we can extend conclusions from the sample to the population from which the same was drawn

• Goal is to draw inferences about the population based on the sample

Statistically Significant Differences

• Statistically significant indicates differences are unlikely due to chance– Probability is less than 1 in 20 (p < .05)

Statistically Significant Differences

• Probability of statistically significant difference is greater when– the difference between means is greater– the smaller the variability of the distributions

Samples and Populations

• Sampling techniques– Random sampling – every member of the

population has an equal chance of being selected