Chapter 2 Notes Research Methods Research design matters 2 modes of thinking Prefrontal lobotomy procedure in which a surgeon severs the fibers connecting the brain s frontal lobes from the underlying thalamus technique used in the early twentieth century as treatment for schizophrenia and other severe mental disorders The same psychological processes that serve us well in most situations predispose us to errors in thinking 1 Intuitive thinking system 1 thinking our first impressions at times are surprisingly accurate quick and reflexive thinking that consists mostly of gut hunches and does not require much mental effort 2 Analytical thinking system 2 thinking slow and reflexive takes more mental effort reasoning through a problem or trying to figure out a complicated concept allows us to override intuitive thinking and reject gut hunches when they seem to be wrong Heuristic a mental short cut or rule of thumb that helps us to streamline our thinking and make sense of our world Research designs systematic techniques developed by scientists in psychology to harness the power of analytical thinking forces us to consider alternative explanations for our findings that our intuitive thinking overlooks 1 Naturalistic observation watching participants behavior in real world settings without trying to manipulate their actions high external validity but low internal validity does not allow us to infer causation awareness of being observed can affect behavior 2 Case studies researchers examine one person or a small number of people often over an extended period of time can provide existence proofs allow us to study rare or unusual phenomena and offer insights for later systematic testing typically anecdotal and don t allow us to infer causation 3 Correlational designs psychologists examine the extent to which two variables are associated can help us predict behavior but don t allow us to infer causation Zero the variables don t go together at all a Correlations can be positive zero or negative b Positive as the value of one variable changes the other goes in the same direction c d Negative as the value of one variable changes the other goes in the opposite direction e Correlation coefficients the statistics that psychologists use to measure correlations range from 1 0 1 0 1 0 being a perfect negative correlation and 1 0 being a perfect positive correlation absolute value of a coefficient the size of the coefficient without the plus or minus sign in front of it unless a correlation coefficient is perfect there will always be exceptions to the trend 4 Experimental designs consist of 2 main components random assignment of participants to conditions and manipulation of an independent variable allow us to infer causation and have high internal validity but can sometimes have low external validity External validity extent to which we can generalize findings to real world settings Internal validity extent to which we can draw cause and effect inferences from a study well conducted laboratory experiments are high in internal validity because we can manipulate the key variables ourselves Existence proofs demonstrations that a given psychological phenomenon can occur Random selection procedure that ensures every person in a population has an equal chance of being chosen to participate crucial if we want to generalize our results to the broader population Reliability refers to consistency of a measurement Test retest reliability a reliable questionnaire will yield similar results over time Interrater reliability the extent to which different people who conduct an interview or make behavioral observations agree on the characteristics they re measuring Validity the extent to which a measure assesses what it claims to measure truth in advertising reliability is necessary for validity Response sets tendencies of research participants to distort their responses to questionnaire items Malingering the tendency of research participants to make ourselves appear psychologically disturbed with the aim of achieving a clear cut personal goal Halo effect the tendency of ratings from one positive characteristic to spill over to influence the ratings of other positive characteristics i e people perceive physically attractive people as more successful confident assertive and intelligent than other people Scatterplot a grouping of points on a two dimensional graph in which each dot represents a single person s data used in correlations Illusory correlation the perception of a statistical association between two variables where none exists Random assignment randomly sorting participants of an experiment into two groups 1 Experimental group group receiving the manipulation 2 Control group group does not receive manipulation Independent variable the variable that the experimenter manipulates Dependent variable the variable the experimenter measures to see whether the manipulation had an effect Operational definition a working definition of what a researcher is measuring when we define our dependent and independent variables Confounding variable refers to any variable that differs between the experimental and control groups other than the independent variable The placebo effect improvement resulting from mere expectation of improvement Blind unaware of whether one is in the experimental or control group The nocebo effect harm resulting from the mere expectation of harm Experimenter expectancy effect AKA Rosenthal effect phenomenon in which researchers hypotheses lead them to unintentionally bias the outcome of the study Double blind when neither researchers nor participants are aware of who s in the experimental or control groups Demand characteristics cues that participants pick up from a study that allow them to generate guesses regarding the researcher s hypothesis Institutional review board IRB reviews all research carefully with an eye toward protecting participants against abuses Informed consent informing research participants of what is involved in a study before asking them to participate Debriefing process performed at the conclusion of a research session in which researchers inform participants what the study was about the study becomes a learning experience for not only the investigator but also the subject Statistics the application of mathematics to describing and analyzing data Descriptive statistics describe data Central tendency measure of the central scores on a data set or where the group tends to