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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
7
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
8
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.
20
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.
23
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
24
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
31
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?
32
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.
34
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.
35
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.
36
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
51
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