Week 2 Ch 1-2

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Cognitive Sciences
Thomas Michael D' Zmura

CHAPTER 1: RESEARCH METHODS Making Observations • Look for patterns within our observations  variables- any characteristic whose values can change Defining the Question • Guided by questions we hope to address through our observations • Formulate the question in a way that leaves no doubt about how we’re going to link the question to the evidence we collect • Testable hypothesis- a prediction that has been formulated specifically enough so that it is clear what observations would confirm the prediction and what observations would challenge it o Testability guaranteed by ensuring the hypothesis is falsifiable • To address a question, we need to develop an operational definition- a definition that translates the variable we want to assess into a specific procedure or measurement • Dependent variable- variable that is measured or recorded in an experiment; independent variable- variable that the experimenter manipulates as a basis for making predictions about the dependent variable Systematically Collecting Data • Memories are often selective; confirmation bias • Anecdotal evidence (evidence that involved 1-2 cases) not used to draw conclusions Defining the Sample • Psychologists often want their conclusions to apply to a particular population- the entire group about which the investigator wants to draw conclusions o Investigators study only a sample- the subset of a population that the investigator studies in order to learn about the population at large • Because each person is different from one another  random sampling- a procedure in which every member of the population has an equal chance of being picked to participate in a study o Other approaches:  If want to examine how diverse population is  maximum variation sampling (deliberately seek out unusual cases)  Case study- an intensive study of one person • H.M. – most studied man in history, suffered memory deficits • Phineas Gage – frontal lobe damage Assessing External Validity • If we want our study to reflect the broader world, we need to ensure its external validity- the degree to which a study’s participants, stimuli, and procedures adequately reflect the world as it actually is o Sample of people in study must be representative of the broader population Monitoring Demand Characteristics • Demand characteristics- the cues in a study that might tell a research participant what behaviors are expected or desirable in that setting • To minimize a study’s demand characteristics: o 1. Try to phrase questions as neutrally as possible o 2. Treat all study participants alike  Double-blind design- the technique of assigning participants to experimental conditions while keeping both the participants and the researchers unaware of who is assigned to which group Working With Data • Analysis involves two parts: o 1. Descriptive statistics- allow a researcher to characterize a data pattern; include measures of central tendency and of variability o 2. Inferential statistics- allow a researcher to draw further claims from a data pattern, including claims about whether the pattern observed in the sample is likely to be observed in other samples Descriptive Statistics • Means and Variability o Measure of central tendency  Mean- calculating sum of all observations, then dividing by number of observations  Median- measure of central tendency taken by putting the data values in order and finding the value that divides the distribution in half o Variability- the degree to which scores in a frequency distribution depart from the central value  Standard deviation- measure of the variability of a data set, calculated as the square root of the variance (V) • Correlations o Correlation- tendency of two variables to change together; if one goes up as the other goes up, positive correlation. If one goes down as the other goes down, negative correlation o Correlation coefficient (r)- a number that expresses both the size and the direction of a positive correlation, varying from +1.00 (perfect positive correlation) to -1.00  Always calculated on pairs of observations • Correlations and Reliability o Reliability- the degree of consistency with which a test measures a trait or
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