Theories and Hypotheses

Assumptions of science A true physical universe exists Order through cause and effect, the connections can be discovered Knowledge is always incomplete, theories are always tentative. Facts are observed data - in psychology tend to be behaviors – observable behavior Constructs are inferred intermediary processes (e.g. memory)

A construct is not a fact. Construct is inferred from the behavior, then used a basis for predicting new behavior to be observed. Science involves interaction between empirical observation and rational abstraction.

Paradigms Overarching scheme, worldview, collection of theories and conventions Methodological decisions may be affected by the research tradition Paradigm tells you what to study Normal science - incremental quantitative steps Paradigm shifts -qualitative or revolutionary change

Paradigm shifts: Old paradigm fails to account for important problems IF there is another and it does a better job then change paradigms- but if no good alternative then hang on to a bad theory

Paradigm shifts Resist change: group dedicated to old way Commitment to ongoing research Uncertainty about future direction How do I fit in new paradigm? Two or more paradigms may coexist but not communicate with each other

Foundational approach (Popper) – method counts. Falsification of hypotheses based on logic/rigid test with view to throwing out theory In practice scientists do not have as a goal the falsification of their ideas If we threw out every rejected hypothesis science would be poorer Kuhn – science is best understood by examining how scientists behave in practice

Caveats and excuses: Theories rarely abandoned because of one conflicting finding. Especially long standing theories. Beginning theories also may get more slack because they not fully refined. – if we reject everything we have nothing. Tend to look for problems in method or experiment

widely held view that – the alternative successor hypothesis should be able to explain all that the displaced theory did plus new stuff. never observed in practice - it takes time to develop a complex theory - often initially it cannot explain all but develops with time

Theory set of logically consistent statements about behavioral phenomenon best summarizes existing knowledge organizes knowledge in form of laws (precise statements of relationship among variables) provides a tentative explanation serves as the basis for making predictions highly explicit and detailed and testable

No scientific theory is a fact. This does not imply that a theory is just a hunch or that scientists don’t actually know anything so they just have a theory. A good theory is a treasure.

A Good Theory Is falsifiable/testable Is in harmony with other hypotheses in the field Is logically simple – no extra assumptions Should yield deductions (have consequences) Is parsimonious – simple better than complex: Occam’s razor and Morgan’s canon A theory produces predictions and so influences how you study

Occom’s razor : Entities should not be multiplied unnecessarily Isaac Newton stated the rule: "We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances." The most useful statement of the principle for scientists is - “When you have two competing theories which make exactly the same predictions, the one that is simpler is the better."

Morgan’s canon “In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of one which stands lower in the psychological scale”

Problems Circular reasoning All or none bias – completely true/false under all conditions Bias of similarity /difference Bias of language or culture

Logic of testing Logical process of deduction : reasoning from general statements toward some specific event. If theory A correct then event X should occur with some probability greater than chance. The prediction is the hypothesis. Induction is the logical process of reasoning from the specific (individual experimental outcome) to the general (theory).

Impossible to prove a theory true. If bird is a crow then it will be black. a) Here is a black bird it must be a crow b) Here is a yellow bird it cannot be a crow We say that an experiment supports or is consistent with theory but does not prove theory right.

Hypothesis – a prediction about the outcome of an experiment. Scientific hypothesis – generated by a theory. Statistical hypothesis – concrete description of one or more summary aspects of population(s). Grow out or are implied by scientific hypotheses