SCIENCE

What does “theory” mean?

Common Definition

Guess Opinion

General beliefsHypothesisSystem of

ideas/statements

Scientific Definition

A set of scientific facts,abstract principles derived therefrom, and the use ofthose 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)

FACTS LAWS 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

FACTS LAWS 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