Scientific Discovery

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Scientific Discovery

• Laws, Theories, and Hypotheses

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Laws

• Laws are universal statements about the nature if
  things.
• Laws allow for reliable predictions about future
  events
• Goals of science to discover these natural Laws
• Laws of Thermodynamics
• Laws of Motion

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Laws of Psychology?

• Is there a
• Law of attraction
• Law of love
• Law of aggression
• Law of fear
• Law of learning and memory

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Theories

• Theories are general statements about the
  relationship between two or more variables
• Theories emphasize causal relationship between
  variables
• Whereas Laws pertain to every event, Theories
  have boundary conditions
• E.G. they are true given a specific set of
  circumstances

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Theories

• There are sometimes more than one theory to
  explain an event
• Overcrowding causes aggressive behavior
• Alcohol causes aggressive behavior
• Frustration causes aggressive behavior
• Each of these theories may be true under
  different circumstances
• Principle of equifinality states that the same
  outcome may have different causes

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Hypotheses

• An Hypothesis is a test of specific events
  derived from the theory
• Theory Level of alcohol consumption influences
  risk taking behavior
• Hypothesis heavy drinkers will take more risks
  in a simulated driving test than light drinkers

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Making Observations

• Induction
• Make the same observation many times
• induce a theory to account for it
• You are taking specific observations and
  generating a general theory
• Problem
• Could make hundreds of observations, all proving
  you right, but the next observation could prove
  you wrong.

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Deduction

• Going from the general to the specific
• Generate specific hypotheses that are tested
  against the theory
• Makes it possible to show a theory is false but
  never that it is true
• Karl Popper championed falsifiability as a
  necessary part of good scientific testing

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Positive Test Bias
E
K
4
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Hypothesis every card containing a vowel must
have an even number on the other side
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Positive Test Bias
E
K
4
7
6
5
J
A
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Positive Test Bias

• Usually pick once card
• Usually pick the care that verifies hypothesis
• Forget to pick card that can prove hypothesis
  false

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Validation Falsification

• Scientists also fall victim to positive test
  bias.
• Scientists try to prove their hypotheses true
  known as validation
• Must also gather evidence to prove hypothesis
  false

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Benefit of falsification

• Forces repeated experiments
• Can lead to competing scientific theories
• Can lead to revision of theories, making them
  more accurate
• Qualification shows under what conditions
  theories and hypotheses are correct or false

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Summary

• We can not prove anything using Science we
  can say what is highly probable.
• We can set up experiments which can falsify
  theories. This helps us to know what is not
  true/possible or probable
• Scientist are subjected to the biases as the rest
  of the world. We tend to look for confirmation
  and validation above falsification
• Others, who disagree will try to falsify your
  work
• Science is an active process not the sum of
  facts

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Experimental Paradigm

• Experimentation refers to the approach by which
  researchers manipulate variables to determine
  their effects on other variables
• Experiments are very valuable, but are not the
  only tool available to scientists.
• You can observe a lot just by watching Yogi
  Berra
• Experiments are specific manipulations of an
  independent variable to affect a specific
  dependent variable

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Variables

• Independent variable
• Variable that is manipulated by the experimenter
• Dependent variable
• Variable that depends upon the independent
  variable
• Experimenters systematically change the
  independent variable and see how that
  manipulation affects the dependent variable

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Independent and Dependent Variables

• Classical way to manipulate the independent
  variable is the use of a control group and an
  experimental group

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Random sampling and random assignment

• A control group and an experimental group must be
  the same prior to receiving the experimental
  manipulation
• We make sure they are the same by Random Sampling

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Random Sampling

• First you must identify the group you are
  interested in examining
• Everyone in that group must have an equal chance
  of being selected
• Want the ones you select to represent the
  average person you would find within that group

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Random Assignment

• Once you have your random selection of people
  from within the group of interest you randomly
  assign them to the different groups
• Control group
• Experimental group or groups
• You want each group to be the same that is an
  average of the people you selected for your
  random sample

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Statistical Testing

• Use statistics to see if the differences in the
  dependent variable (after the experiment) were
  due to the manipulations in the independent
  variable
• Research begins with the assumption that the
  hypothesis is false you were wrong the
  experimental group and the control group are
  still the same and any differences were due to
  poor random assignment and or sampling
• This is known as the null hypothesis

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Alternative Hypothesis

• The alternative hypothesis states that the
  differences that you see are real. Your
  manipulation worked
• When to accept the alternative v. the null
  hypothesis?
• Alpha level of .05 means that there is a 5
  chance that the results were accidental not
  real