research methods

nature-nurture issue

the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors; today’s science sees traits and behaviors arising from the interaction of nature and nurture

predisposition

the tendency to develop certain genes because of family but not guaranteed

twin studies

because identical twins have the same genes, they are ideal to participate in studies designed to shed light on hereditary and environmental influences on intelligence, personality, and other traits; studies of identical and fraternal twins provide a rich array of findings that underscore the importance of both nature and nurture

adoption studies

studies of adopted children to see how much of their traits come from biological vs. adoptive parents

biopsychosocial approach

integrated approach that incorporates biological, psychological, and social-cultural levels of analysis

behavioral perspective

bandura - psychological approach studying observable behavior and being explained by principles of learning

biological perspective

psychological approach studying links between biological (genetic, neural, hormonal) and psychological processes (some biological psychologists call themselves behavioral neuroscientists or other things)

cognitive perspective

psychological approach studying all of the mental activities associated with thinking, knowing, remembering, and communicating

evolutionary perspective

psychological approach studying evolution of behavior and mind using principles of evolution

humanistic perspective

maslow and rodgers - psychological approach focused on how we meet our needs for love and acceptance and achieve self-fulfillment

psychodynamic perspective

freud - psychological approach studying how unconscious drives and conflicts influence behavior and then using that information to treat people with psychological disorders

social-cultural perspective

psychological approach studying how situations and cultures affect our behavior and thinking

hindsight bias

the tendency to believe, after learning an outcome, that one would have foreseen it

overconfidence

tending to think, as humans, that we know more than we do

theory

explaining and predicting behaviors or events by offering ideas that organize what we have observed

hypothesis

testable prediction, often implied by a theory; these predictions specify what results would support the theory and what would cast doubt our theories can bias our observations

null hypothesis

when the results of a study are not statistically significant, you say that there is no significant relationship, effect, or difference between the variables being studied; it proposes that any observed results are due to random chance

operational definition

carefully worded statement of the exact procedures used in a research study; describes concepts with precise procedures or measures

replicate

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances; operational definitions help a lot with this

descriptive methods

describe behaviors, often by using case studies, surveys, or naturalistic observations

correlational methods

associate different factors, or variables (anything that contributes to a result) to see how they are related

experimental methods

manipulate variables to discover their effects

case study

descriptive technique in which one individual or group is studied in depth in the hope of revealing universal principles; used often for people with things like brain injuries

naturalistic observation

observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

confirmation bias

a cognitive bias where individuals actively search for, interpret, favor, and recall information that confirms their pre-existing beliefs, while ignoring or discounting contradictory evidence

participant bias

when research subjects consciously or unconsciously alter their behavior or answers to align with what they think the researcher wants, rather than responding naturally, skewing results

longitudinal study

tracks the same individuals over an extended period (months, years, or decades) to observe changes, development, or effects

cross-sectional study

research method that collects data from different age groups or populations at a single point in time to compare them, providing a "snapshot" of developmental differences or relationships between variables

survey

technique for ascertaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group; done when wanting to estimate, from a representative sample of people, the attitudes or reported behaviors of a whole population

wording effect

how subtle changes in question phrasing or order in surveys significantly influence participant responses, even if the core meaning is the same

sampling bias

produces an unrepresentative sample

population

group being studied

random sample

fairly represents a population because each member has an equal chance of inclusion

convenience sample

researchers select participants who are easy to access, like students in their own class or people at a mall, because they are readily available and convenient, rather than using random selection, leading to quick, easy, but often biased samples that aren't representative of the broader population, limiting generalizability

correlation

a measure that two variables change together, and how well either variable predicts the other

correlation coefficient

a statistical measure of how closely two things vary together, and thus how well either one predicts the other

scatterplot

dots graphed represent two variables (slope = direction of the relationship between two variables)

correlation & causation

correlation shows a relationship but does not show cause (like if one variable causes another or if they are both caused by something else)

third variable problem

when a correlation between two variables (X and Y) isn't a direct cause-and-effect but is actually influenced by an unmeasured, external variable (Z) that affects both X and Y

illusory correlation

when you think there is a correlation but there isn’t one; explains superstitions

regression towards the mean

the statistical tendency for extreme scores (very high or very low) on an initial test or measurement to be followed by scores that are closer to the average (mean) upon retesting, due to the influence of chance

experiment

type of research where you manipulate variables to discover their effects

experimental group

group that receives treatment

control group

group that doesn’t receive treatment

random assignment

minimizes pre-existing differences by randomly assigning participants to experimental or control groups

single blind procedure

an experimental technique where participants are unaware of whether they are assigned to the experimental group or the control group, while the researchers know

double-blind procedure

a research method where neither the participants nor the researchers/staff know who's in the experimental group (getting the treatment) and who's in the control group (getting the placebo), preventing both participant bias (expectations) and experimenter bias (unintentional influence) from affecting results, ensuring more objective data, especially in drug trials

placebo effect

shows how effective a drug really is because one might think they are experiencing the effects of something because they assume they will

independent variable

variable whose effect is being studied

confounding variables

an outside, unmeasured factor in a study that influences both the independent variable (cause) and the dependent variable (effect)

dependent variable

variable being studied

validity

how well a study measured what it aimed to measure

descriptive statistics

numerical data used to measure and describe characteristics of groups; includes measures of central (main) tendencies and measures of variation

frequency distribution

a summary table or graph (like a histogram or polygon) organizing data points to show how often specific scores or ranges of scores occur

frequency polygon

a line graph used to represent frequency distributions, created by plotting points at the midpoint of each class interval and connecting them with straight lines

histogram

bar graph depicting a frequency distribution

likert scales

a common survey tool measuring attitudes or opinions by asking respondents to rate agreement with statements (e.g., "Strongly Agree" to "Strongly Disagree") or frequency (e.g., "Always" to "Never") on a symmetric, numerical scale, quantifying subjective feelings for easier data analysis in research like survey research

measure of central tendency

descriptive statistics that identify the center or typical score in a dataset: mean (average), median (middle score), and mode (most frequent score)

mean

average value

median

middle/central value

mode

most frequently occuring value

positive skew

more scores are lower, with a few very high outliers (ex. a test where most students score low, but a few score really high)

negative skew

more scores are higher, with a few very low outliers (ex. a test where most students score high, but a few score really low)

measures of variation

describe the spread or dispersion of data points in a distribution, indicating how clustered or scattered scores are around the mean; range, variance, and standard deviation

range

difference between highest and lowest scores; only gives a crude estimate of variation

percentile rank

shows the percentage of test-takers who scored the same or lower than you on the exam, with higher percentages indicating better performance

standard deviation

computed measure of how much scores vary around the average; large numbers of data in a standard deviation graph (not income though) often form a bell curve

normal curve

bell curve that describes the distribution of many types of data; most scores fall near the mean (about 68% within one standard deviation of it) and fewer and fewer near the extremes

inferential statistics

numerical data that allow one to generalize

meta-analysis

a statistical research method where a psychologist combines and analyzes results from many individual studies on the same topic (like therapy effectiveness or choice overload) to find overall patterns

statistical significance

a statistical statement of how likely it is that an obtained result occurred by chance; when sample averages are reliable, and when the difference between them is relatively large, we say it has statistical significance, meaning the observed difference is likely not due to chance variation between samples

p-value

value that shows a study’s results’ statistical significance; must be less than 0.05 or 5%

N

the total number of subjects, participants, or observations in a study or population

effect size

measures the magnitude or strength of a relationship between variables, indicating the practical significance or real-world impact of research findings

protection from harm

an ethical guideline for research that ensures research protect participants from physical or emotional harm and discomfort

confidentiality

an ethical guideline for research that ensures researchers keep information about individual participants confidential

debriefing

an ethical guideline for research that ensures researchers fully debrief participants on the details of the study

institutional review board (IRB)

an ethics committee that screens research proposals and safeguards participants’ well-being