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PSYA01H3 Lecture Notes - Uncorrelated Random Variables, Falsifiability, Frequency Distribution

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Steve Joordens

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Empiricism: How to Know Stuff
2 kinds of doctors long ago:
1. Dogmatists best way to understand illness was to develop theories about the
body’s function
2. Empiricists - best way to understand illness was to observe sick ppl
Empiricism = The belief that accurate knowledge can be acquired through observation
The Scientific Method
Empiricism is the essential element of the scientific method
Scientific Method = A set of principles about the appropriate relationship b/w ideas and
Is the Idea = Theory = A hypothetical explanation of a natural phenomenon
o The Rule of Parsimony = When scientists start to develop a theory they start with the
simplest one (William Ockham)
Hypothesis = A falsifiable prediction made by a theory
The Art of Looking
Empirical Method = A set of rules and techniques for observation
Methods = refers primarily to technologies that enhance the powers of the senses
3 Things that make ppl hard to study:
1. Complexity human brain is complicated
2. Variability no 2 individuals ever say, think, or do the same thing under the same
3. Reactivity ppl act differently when they are being observed
Observation: Discovering What People Do
Defining and Detecting
Operational Definition = A description of a property in concrete, measurable terms
Measure = A device that can detect the condition to which an operational definition refers
Steps to measure a psychological property:
1. Start by developing an operational definition of a property (i.e. use frequency of
smiles to determine a person’s happiness)
2. A device that measures these events (i.e. EMG to detect smiles)
a. Electromyography (EMG) = A device that measures muscle contractions
under the surface of a person’s skin

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Validity, Reliability, and Power
Good measures have 3 properties:
o Validity = The extent to which a measurement and a property are conceptually related
o Reliability = The tendency for a measure to produce the same measurement whenever
it is used to measure the same thing
o Power The ability of a measure to detect the concrete conditions specified in the
operational definition
Demand Characteristics
Demand Characteristics Those aspects of an observational setting that cause ppl to behave as
they think they should
o Demand/require ppl to say/do things they normally might not say (ex. Do these jeans
make me look fat? no, ofc not.)
o To avoid the demand characteristic problem ppl observe others w/o their knowledge
Naturalistic Observation A technique for gathering scientific info by
unobtrusively observing ppl in their natural environments
2 Problems w/ Naturalistic Observation:
Things psychologists want to observe simply doesn’t occur naturally
Some things can only be gathered from direct interaction
o Ways to Avoid Demand Characteristics:
Anonymously or privately volunteer info
Behaviours that are not susceptible to demand
Ppl don’t know what the demand and behaviour are related
Blind to the true purpose of the observation cover stories or filler items
Observer Bias
o Expectations can influence observations
o Expectations can influence reality
o Psychologists use many techniques to avoid these influences, such as double-blind observation
o Double-blind = An observation whose true purpose is hidden from both the observer
and the person being observed
Graphic Representations
Psychologists often create graphic representations of the measurements they collect:
o Frequency Distribution = A graphical representation of measurements arranged by the
number of times each measurement was made
Frequency distribution can have any shape but is a common bell shape, which is
known as the Gaussian Distribution or normal distribution
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