SCIENCE What does “theory” mean? Common Definition Guess Opinion General beliefs Hypothesis System of ideas/statements Scientific Definition A set of scientific facts, abstract principles derived therefrom, and the use of those principles to explain new facts
“Theory” Defined Let's start with the FACTS: Theories begin with observations Observations lead to functional relations Functional relations= facts In essence, scientific theories are derived from scientific facts
“Theory” Defined Scientific theories emerge from generalizations that are a result of the accumulation, grouping, and ordering of scientific facts This definition varies from “theory” used in many developmental psychology texts
Theory Development A theory makes sense of these accumulated facts by ordering observations at several levels of specificity (Poling, Schlinger, Starin, and Blakely, 1990, p.32) FACTSLAWS THEORY Each level is based on the previous level
Scientific Facts A functional relation between two events Individual and between classes Based on observations that are reliable and repeatable Different from casual observations Example: When certain consequences immediately follow behavior in lab rats, the frequency of the behavior will increase
Scientific Laws Functional relations (facts) are ordered into more general statements (laws) Descriptions of relatively constant relationships between certain kinds of phenomena (McCain & Segal, 1988). Reproducibility of relationships is key Example: The Law of Effect- behavior is a function of its consequences
Scientific Theory Laws are ordered into even more general statements (theories) Theory is built upon An established body of facts General or abstract principles from those facts used to explain the phenomena Example: Reinforcement Theory *This definition is at odds with the non-science definition of theory as an educated guess
Scientific Theory Purpose of theories: To unify and explain a body of data (Green, 1989) by Describing observed events Predicting what will be observed under certain conditions Interpreting knowledge and understanding beyond the laboratory In line with the purpose of science Control, Prediction, Understanding
Theory- Prediction Scientific Prediction “Control” over subject matter is achieved when functional relations are discovered Once control is established, scientist can make predictions about what will happen under certain conditions Prediction relies on controlled conditions and specific information about variables
Theory- Prediction Prediction in Developmental Psychology Correlational method is used to determine “average” for a specific group
Theory- Interpretation Scientific interpretation involves applying knowledge and understanding of functional relationships observed in the laboratory to observations in the “real world” Relies on a foundation of well-established principles from basic research
Evaluating Scientific Theory 1.Generality (Inclusiveness) 2.Testability 3.External Validity (Accuracy) 4.Fruitfulness (Utility) 5.Simplicity (Parsimony)
Evaluating Scientific Theory Generality (Inclusiveness) Explains other related scientific facts Testability Empirical support (observations) Logical support (plausible mechanisms) External Validity (Accuracy) Precise predictions that can be tested
Evaluating Scientific Theory Fruitfulness (Utility) Stimulates new research and generates practical applications Simplicity (Parsimony) “Theoretical Economy” Accounts for body of data with fewest assumptions and statements
Scientific Understanding Is achieved at each level of specificity FACTSLAWS THEORY Sound theories enhance scientific understanding Criterion of Inclusiveness Explain seemingly different phenomena according to set of laws Acknowledge conditions under which it may not explain behavior Criterion of Generality Continue to predict and explain phenomena as they are encountered