PSY 2012 0004 Katie s Notes Chapter 2 Scientific Methods in Psychology 2 1 Thinking Critically and Evaluating Evidence Evidence and Theory in Science Science is a word derived from Latin roots scientia meaning knowledge Scientific practices help psychologists to gain the most accurate and useful knowledge of mental processes and human behavior Psychology is a science Scientific method provides the guidelines for scientists in all fields including psychology to use in evaluating discrete claims It is almost impossible to prove that a claim or theory is true beyond a doubt The scientific method allows us to reach conclusions that are very likely to be true Theory an explanation or model that fits many observations and makes valid predictions consistently Falsifiable stated in such clear precise terms that we can see what evidence would count against it the point of research is to falsify the incorrect theories and a good theory is one that withstands all attempts to falsify A well formed theory is therefore falsifiable Example The telephone psychic says Next year your life will change This is not falsifiable It is vague Burden of proof the obligation to present evidence to support one s claim Steps for Gathering and Evaluating Evidence 1 Hypothesis conditions a A testable prediction of what should occur under a precisely stated set of b Scientists seek evidence that will support or disprove a claim c A good hypothesis leads to predictions 1 PSY 2012 0004 Katie s Notes 2 Method 3 Results 4 Interpretation a If they contradict the hypothesis researchers should abandon or modify the original hypothesis Replicability Replicable results are those that anyone can obtain at least approximately by following the same procedures The importance of replication Testing of hypotheses must be repeated Researchers must report their methods in great detail This allows other scientists to repeat studies in order to confirm or contradict the validity of findings Meta analysis combines the results of many studies and analyzes them as though they were all one very large study Small to medium effects predominate in studies of certain phenomena sex differences in aggressive behavior for example The results of studies are compiled and treated as one very large research study This provides more information about the circumstances that influence the occurrence of the predicted effect Criteria for Evaluating Scientific Theories What do we do if several theories fit the known facts For example suppose you notice that a picture on your wall is hanging on an angle You consider three possible explanations 1 A mild earth tremor shook the picture 2 One of your friends bumped it without telling you 3 A ghost moved it All three explanations fit the observation but we don t consider them on an equal basis When given a choice among explanations that seem fit the facts we prefer the one whose assumptions are fewer simpler or more consistent with other well established theories Parsimony Occam s razor we stick with the ideas that work and try as hard as we can to avoid new assumptions i e ghosts Open mindedness the willingness to consider proper evidence It s not unquestioning acceptance of any possibility in the absence of evidence That s gullibility How open minded we are depends on the quality and parsimony of evidence presented Personal accounts of isolated events can bolster beliefs in phenomena such as ESP or premonitions extrasensory perception ESP at least some people some of the time can acquire information without using any sense organ and without receiving any form of physical energy 2 PSY 2012 0004 Katie s Notes One king of evidence consists of anecdotes people s reports of isolated events such as an amazing coincidence or a dream or hunch that comes true We are prone to selective memory AKA confirmation bias We only remember hunches that are proved correct We like to be right 2 2 Conducting Psychological Research General Principles of Psychological Research Operational definition a definition that specifies the operations or procedures used to produce or measure something ordinarily a way to give it a numerical value Population the entire groups of individuals to be considered Population Samples Research questions may be relevant to a large group of interest such as seven to ten year old children people diagnosed with depression Because it is not practical to examine everyone in the population researchers study a sample of people and assume that the results for the sample apply to the whole population Convenience sample group chosen because of its ease of study Representative sample closely resembles the population in its percentage of males and females Blacks and Whites young and old etc Random sample every individual in the population has an equal chance of being selected Cross cultural sample groups of people from at least two cultures Sample Individuals included Convenience Anyone who is available Representative Same of male female young old etc as the whole population Random Everyone in population has same chance of being chosen Advantages and Disadvantages Easiest to get but results may not generalize to the whole population Results probably similar to whole population although sample may be representative in some ways but not others Difficult to get this kind of sample but it is the best suited for generalizing whole population barriers cooperation problems etc but essential for studying many issues Cross cultural People from different cultures Difficulties include language 3 PSY 2012 0004 Katie s Notes Eliminating the Influence of Expectations Experimenter bias the tendency of an experimenter unintentionally in most cases to distort or misperceive the results of an experiment based on the expected outcome Preventing this problem Blind observer an observer who records data without knowing the researcher s predictions Placebo a pill with no pharmacological effects when you give one group a fake pill or treatment and you give the other group the real one Single blind study either the observer or the participants are unaware of which participants received which treatment Double blind study both the observer and the participants are unaware Demand characteristics cues that tell participants what is expected of them and what the experimenter hopes to find Observational Research Designs Naturalistic observations a careful examination of what happens under more or less natural conditions Example Dr Jane