1. Scientific Method and Experimentation

2. *BOTH METHODS ARE INDISPENSIBLE*
Two ways of thinking
Induction
Form of thinking in which one starts with a number of separate observations and then arrives at general principles
Deduction
Form of thinking in which one reasons from general principles to specific conclusions
*BOTH METHODS ARE INDISPENSIBLE*

3. INDUCTION

4. INDUCTION Make a series of individual observations
IDEALLY, Have no goal or hunch as to outcome

5. INDUCTION
Example
Suppose a particular marine biologist examined a sailfish, a shark, and a tuna, and found that they all had gills. Since sailfish, sharks, and tuna are all fishes, he might draw the general conclusion:
ALL FISH HAVE GILLS

6. INDUCTION
PITFALLS
The number and quality of the observations is critical in developing a general statement
If the biologist had only examined sailfish, which happen to have a bill, he might use information to develop a false statement, “ALL FISH HAVE BILLS.”
Even after examining all three types of fish he may have concluded, “ALL MARINE FISH HAVE GILLS” instead of just “ALL FISH HAVE GILLS”

7. DEDUCTION

8. DEDUCTION Start with a general statement about nature
Predict what specific consequences would be if the general statement is true

9. DEDUCTION THEREFORE DEDUCTION AND INDUCTION ARE LINKED!!!!!!
In the process of deduction, applying a general principle allows one to make specific predictions
The scientist may arrive at the general statement by intuition or hunch, but most often the statement is the result of INDUCTION
THEREFORE DEDUCTION AND INDUCTION ARE LINKED!!!!!!

10. DEDUCTION LIMITATIONS
Suppose the general statement is, “ALL MARINE ANIMALS HAVE GILLS”
May lead to the assumption that DOLPHINS have gills since they live in the water

11. INDUCTION + DEDUCTION
Both induction and deduction lead scientists to make a statement that might be true
Scientists need to test these statements to see whether they are, in fact, true

12. HYPOTHESIS A statement that might be true
Must be tested, usually over and over again
Constructing a hypothesis
Hypotheses must be stated in a way that enables them to be tested
It must be possible to prove the hypothesis false, if it is false

13. HYPOTHESIS Example Hypothesis “WHALES HAVE GILLS”
Examine a whale to see whether it has gills
Discover whales have lungs not gills
Disproves hypothesis, “WHALES HAVE GILLS”
Also disproves more general hypothesis, “ALL MARINE ANIMALS HAVE GILLS”

14. HYPOTHESIS Pitfalls Propose a hypothesis that cannot fairly be tested
Example
“SOMEWHERE IN THE OCEAN THERE ARE MERMAIDS”
Scientists may never find a mermaid, but believer could say “THE MERMAIDS ARE THERE YOU JUST DIDN’T FIND THEM”
No matter how hard you look you can never prove there are no mermaids
“THERE ARE NO MERMAIDS IN THE OCEAN” is not a valid hypothesis

15. HYPOTHESIS
Overview
A scientific hypothesis is a statement about the world that might be true and is TESTABLE
A testable hypothesis is one that at least potentially can be FALSE

16. The Nature of Scientific Proof
It must be at least possible to disprove a hypothesis before the hypothesis can be considered scientific
Ways to Prove a Hypothesis True
In general, no scientific hypothesis can be proven ABSOLUTELY TRUE
There are no absolute truths in science

17. The Nature of Scientific Proof
Scientific hypotheses are tested repeatedly to see if they agree with actual observations of the world
A hypothesis that withstands repeated testing is provisionally accepted as true
EXAMPLE
Scientists accept the hypothesis “ALL FISH HAVE GILLS” because every attempt to reject it has failed
NO hypothesis can be scientifically proven true!!!!!
Hypotheses are accepted for as long as the available evidence supports them!!!

18. Testing the Hypothesis

19. Testing the Hypothesis

20. Testing the Hypothesis
Problem
Do oysters grow faster in warm or cold water?
Approaches
Find two places, one warm, one cold and measure how fast the oysters grow at each place

21. Testing the Hypothesis
Pitfall
The temperature at any given place will change all the time. Biologists would have difficulty finding two locations where one is always warmer than the other
May be other differences!!!
Different types of food
Different amounts of food
Pollution
Outbreak of disease
AND MANY MORE!

22. Testing the Hypothesis
In any natural setting there will be countless factors to consider other than the one to be tested for
Factors that might affect observations are called variables
Overcoming pitfalls
Run experiment in holding tanks where extraneous variables such as amount and type of food can be controlled
Controlled variable
Variable that scientists artificially keeps from changing to prevent it from affecting the experiment

23. The Scientific Theory
A theory is a hypothesis that has passed so many tests that it is generally regarded as true
Theories, like hypotheses, cannot be absolutely proven
Theories are only accepted so long as they are supported by evidence
A scientific theory is a hypothesis that has been so extensively tested that it is generally regarded as true. Like any hypothesis, it is subject to rejection if enough evidence accumulates against it

24. Limitations of the Scientific Method
No one can be absolutely objective at all times, personal biases may affect thinking
Science can not make judgments about values, ethics, or morality

25. Methods of Conducting Experiments
A study in which the investigator manipulates at least one other variable
Independent Variable
The variable the investigator manipulates
Dependent Variable
The variable that is measured, that changes in response to the independent variable

26. Methods of Conducting Experiments
Experimental Group
Receives the treatment that the experiment is designed to test
Control Group
Is treated in the same way as the experimental except for the experimental treatment

27. Methods of Conducting Experiments
Single Blind Studies
Subjects are unaware of which subjects received the treatment
Placebo
Inactive Pill
Blind Observer
An observer who does not know which subjects are in which group and what is expected of each
Double Blind Study
Both the observer and subjects are unaware

28. General Principles of Conducting Research
Defining Variables
Examples
Decide what terms like “motivation” or “love” mean
Psychologists use operational definitions
A definition that specifies the operations or procedures used to measure some variable or produce some phenomenon
Example
Love  the amount of time a person will go without a personal need to take care of another’s needs

29. General Principles for Conducting Research
Random Sample
Every individual in the population has an equal chance of being selected
Relative Sample
Closely resembles the entire population in its percentage of males and females, ethnic groups, religions, etc.

30. Evaluation of Evidence
Replicable Results
Anyone who repeats the same procedure will get the same results
Trial 1
Trial 2

31. Theories
Comprehensive explanations of natural phenomena that lead to accurate predictions
Criteria for evaluating scientific theories
Good theories
Reveals patterns in the observations we make
Predicts new observations
Is falsifiable
Is parsimonious