how do we know? psych 231: experimental psychology
TRANSCRIPT
How do we know?
Psych 231: Experimental Psychology
Exercise: How do we know?
Write down two things that you “know”. Write down HOW you “know” those
things.
Methods of Inquiry
Type of knowledge– Objective - having “real” existence
outside of a person’s mind – Subjective - existing in a person’s mind
Ways of knowing– Analysis - finding supporting evidence– Acceptance - taking as true
Methods of Inquiry
Objective Subjective
Analysis
Acceptance
Methods of Inquiry
Objective Subjective
AnalysisEmpiricism (Experience)
Logical reasoning
Acceptance
Methods of Inquiry
Objective Subjective
AnalysisEmpiricism (Experience)
Logical reasoning
Persuasion (by logicalmeans)
Acceptance
Methods of Inquiry
Objective Subjective
AnalysisEmpiricism (Experience)
Logical reasoning
Persuasion (by logicalmeans)
AcceptanceAuthorityInstructionRegulation (rules & laws)
Methods of Inquiry
Objective Subjective
AnalysisEmpiricism (Experience)
Logical reasoning
Persuasion (by logicalmeans)
AcceptanceAuthorityInstructionRegulation (rules & laws)
Personal preferenceFaithIntuition
Methods of Inquiry
The scientific method– We’ll learn how to test and analyze claims
about behavior using scientific methods of systematic observation and experimentation.
Scientific Method
– write down two generalizations that you have observed about people’s behavior.
Step 1: Observation– Pay attention to the world around you, look for
generalizations– Two kinds of generalizations
• Descriptive generalizations – just describe how it is/what was seen, without making predictions
• Cause and effect generalizations – makes predictions about the observed relationship between two (or more) things.
Scientific Method
Step 2: Develop a theory or hypothesis– An explanation for the observed
behavior(s)• May be based on past research, common
sense, intuition, logic, etc.
Scientific Method
Step 3: Generate a testable prediction– Need to specify how your hypothesis can
be tested.– Falsification is at the heart of the scientific
method– More on this next lecture
Scientific Method
Step 4: Make systematic observations– Observational and experimental methods
• What are the relevant variables?• How do we measure the variables?• What needs to be controled?
– Much of the rest of this course deals with these
Scientific Method
Step 5: Evaluate your evidence– Refutes theory– Supports theory– Leads to the revision of the theory– Consider alternative theories
The importance of a critical eye
There are always alternative explanations:– Coke vs. Pepsi
The Pepsi Challenge Pepsi did a taste test in Dallas (Coke had a 3:1
lead). Wanted to find out if drinkers really preferred Coke or if it could be attacked by advertising.
Chose set of Coke drinkers, gave glass with Coke and one with Pepsi
Any problems with this experiment? Should not actually label like that – Why?
The Pepsi Challenge Next version: labeled by letters – M (Pepsi) and Q
(Coke). Found that more than half chose Pepsi.
OK? Turns out that it is not so OK.
What if some letters preferred more than others? Could this account for the results?
Yes Seems strange, but how would you test?
The Pepsi Challenge Pepsi did the test again, need to control for
label, so they counterbalanced order.
To be convincing then, for half the tasters the labels should be one way and for the other half the other. Then can rule out label preference. (What about order that things are tasted? )
The importance of a critical eye
There are always alternative explanations:– Coke vs. Pepsi– Psychic Uri Geller
Psychic watch repair Uri Geller, famous psychic. In Australia
(and other places), would “heal” watches in audiences and even over radio.
How did he do it? Geller’s claim: Psychic energy from him.
Psychic watch repair
Problem: Someone else replayed tape of the broadcast and found it worked then too
Alternative explanation: Old watches usually not working because oil gummed up. Heat of hands is sufficient for a short time.
Experimental Solution: Add a control group– a group of people with broken watches who do everything the
same (including covering the watch) but don’t get Uri’s psychic energies
Geller relied on people believing that since watches had not been working that it was his energy, as opposed to the other changes (such as holding) that was responsible
Next week
Getting ideas for your experiments Read chapter 2 this weekend