Psychology Chapter 2
Psychology Chapter 2 Psych1100
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Chapter 2 Methods in Psychology Introduction Freeman performed Lobotomies which is a surgery for mental illnesses The rst surgeries went in through the eyes and they separated the frontal lobe from the rest of the brain to quotcurequot the illness Why does research design matter Intuition and impressions are often wrong Psychology is a science Empiricism the belief that we can acquire accurate knowledge through observation Scienti c method a set of principles about the appropriate relationship between ideas and evidence Theories vs Hypotheses Theory a hypothetical explanation of a natural phenomena Rule of parsimony Example Evolution because it cannot be proven cannot conduct research to prove it so it will remain a theory Hypothesis a falsi able prediction made by a theory Can be tested and therefore can be proven Applying empiricism Empirical method a set of rules and techniques for observation It is hard to study people because people are Complex Variable Reactive Must use methods of observation and methods of explanation Measurement Operational de nition a description of a property in concrete measurable items 0 Example to do a study on depression since there are so many different variables and reactions to depression researchers must have an operational de nition so that their study is speci c to one characteristic or maybe a few but they are all relative Measure a device that can detect the condition to which an operational de nition refers 0 Examples EMG BMI BDI etc Good measures have 0 Validity the extent to which a measurement and a property are conceptually related 0 Reliability the tendency for a measure to produce the same measurement whenever it is used to measure the same thing 0 Power the ability of a measure to detect the concrete conditions speci ed in the operational de nition In order for something to be reliable it must be valid Naturalistic Observation Naturalistic Observation is a technique for gathering scienti c information by unobtrusively observing people in the natural environments 0 When this is unavailable use quotblindquot conditions cover stories ller items ie asking irrelevant questions so they do not know exactly what questions you are interested in Why Naturalistic Observation Demand characteristics those aspects of an observational setting that cause people to behave as they think they should 0 To avoid this do not let people know they are in the study An example of this is an experiment to see if it takes longer for males to start peeing if another male is close to them rather than further than them One researcher hide with stopwatch and have someone go stand farther or closer to someone and see the differences in the time Observer bias expectations can in uence observations and in uence perceptions of reality 0 Example of experiment is the horse who can count but one psychologist pointed out that the horse may be reading the person39s body behavior so to avoid that they did a double blind experiment and the horse did not know when to stop because he could not read anyone39s body behavior 0 Double blind an observation whose true purpose is hidden from both the observer and the person being observed Descriptions and Graphic representations Graphic representations describe data 0 Frequency distribution a graphical representation of measurements arranged by the number of times each measurement was made Normal distribution most measurements are concentrated around the middle ln psychology researchers often pretend that they have a normal distribution Skewed distributions are nonnormal positive or negative skewed Descriptive Statistics Descriptive Statistics describe a frequency distribution Central tendency center or midpoint Mode the value of the most frequently observed measurement Mean average of all the measurements Median the value that is in the middle Variability extent that measurements offer Range value of the largest measurement in a frequency distribution minus the value of the smallest measurement Standard deviation statistic that describes the average differences between the measurements in a frequency distribution and the mean of that distribution Descriptive statistics are helpful but they do not tell what we want to know in psychology The ultimate goal of psych is the discovery of casual relationships between properties Study patterns of variation in a series of measurements Variable a property whose value can vary across individuals or overtime We want inferential statistics in psychology Correlation Correlation two variables are correlated when they change with the same pattern Ex Height and weight in childrenas height increases so does weight Positive correlation both increase or decrease together Negative correlation one variable increases and the other variable decreases 0 Correlation coefficient a measure of the direction and strength of a correlation r rranges from 10 perfect negative correlation to 10 perfect positive correlation with ro as no correlation The strongest correlation is the correlation that is closest to either 10 or 10 the negative sign or positive sign does not play a factor in that Ex 95 is a stronger correlation than 90 Causation Sometimes we see casual relationships that don39t actually exist Natural correlations a correlation observed in the world around us Third variable problem the fact that a causal relationship between two variables cannot be inferred from naturally occurring correlation between them because of the possibility of third variable correlation 0 Third variable correlation the fact that two variables are correlated only because each is casually related to a third variable Matched samples a technique in which the participants in two groups are identical in terms of a third variable everyone has the same third variable Matched pairs a technique where each participant is identical to one other participant in terms of a third variable only pairs have the same third variable the pairs with other pairs do not have the same third variable Correlation does not imply causation 0 Children raised in homes With more appliances tend to perform better in school Therefore appliances improve intelligence Not the actual number of appliances that are helping students but more appliances generally means higher income and higher income typically have access to better education therefore will perform better in schooL Experimentation Experiment is a technique for establishing the casual relationship between variables Experiments require 1 Manipulation the creation of an arti cial pattern of variation in a variable in order to determine its casual powers i Independent variable the variable that is manipulated ii Dependent variable the variable that is measured in the study 1 Typically written in a sentence such as quotThe effect on independent variable on dependent variablequot 1 Random Assignment a procedure that uses a random event to assign people to the experimental or control group 0 Experimental groups the group of people who are treated in a particular way in an experiment 0 Control group the group of people who are not treated in the particular way that the experiment group is treated in an experiment Selfselection a problem that occurs when anything about a person determines whether he or she will be included in the experimental of control group would create a third variable if we let them pick their own group Ways to avoid this ip a coin select groups for heads and tails pick names out of hat etc Drawing conclusions Statistical signi cance is determined when we calculate the odds that random assignment as failed through inferential statistics 0 Something is only signi cant if the chance of failure of random assignment is less than 5 plt05 lnternal validity the characteristic of a study that established the casual relationship between variables Needs well conducted study External validity the property of a study in which the variables have been operationally de ned in a normal typical or realistic way39 are they representative of the real world External validity requires a representative sample In an experiment a researcher cannot observe an entire population so instead draws a sample 0 Population the complete collection of participants who might possibly be measured Sample the partial collection of people drawn from a population Case method a method of gathering scienti c knowledge by studying a single individual 0 Random sampling a technique that ensures that when picking a sample every member of the population has the chance to be represented Pick every 15th person off the list etc Random sampling vs Random assignment Random sample is choosing who is in the group while random assignment is taking the subjects that are already in the groups and randomly assigning them to groups 0 Nonrandom sampling is only acceptable if the similarity between the sample and population does not matter when replication is available and if the similarity between the two is reasonable enough 00 Hot Science Do violent movies make peaceful streets Studies have shown a relationship between media violence and aggression When economists ran a correlation they found that on evenings when more theater to watch a violent movie there were fewer violent crimes committec correlation The ethics of science 1 Do no harm o Psychologists go to great lengths to protect the wellbeing of research participants and are bound be a code of ethics 0 Respect for persons research should be bene cent research should be just 0 APA code of ethics 0 Informed consent freedom from coercion protection from harm riskbene t analysis debrie ng con dentiality 0 Ethical reporting of data and approval from institutional review boards necessary 0 Must report truthfully share credit and share data 1 Respecting Animals 0 All procedures involving animals must be supervised by trained psychologists o Discomfort and pain must be minimized True Experiments For an experiment to be true there must be random assignment and an independent variable