Experimental PsychologyPSY 433

Chapter 1 – Explanation in Scientific Psychology

Scientific Curiosity

“…Scientists are willing to go to much greater lengths to satisfy their curiosity than are nonscientists.” Kantowitz et al, pg 5

Scientists want to know answers but are also willing to tolerate a lack of clear answers.

Skepticism is the philosophical belief that the truth of all knowledge is questionable. No fact can be known with 100% certainty.

Science vs Non-science

Nonscientific beliefs come from: Authority -- believe because an authority told you

(take it on faith) Religious views are acquired this way

Tenacity -- believe in spite of contrary evidence (cling to belief, refuse to change)

Bigotry results from this approach A-priori methods -- believe without prior study

(believe what seems reasonable) Scientific beliefs are based on experience.

We can determine the causes of events through observation.

Scientific Method

The scientific method is designed to eliminate human problems with thinking.

Belief is based on empirical observation. Empirical means “based on experience” Observation must be systematic, not

haphazard, selective or confirmatory. An advantage of science is that it provides a

way of selecting one belief over another. It is self-correcting because beliefs are

abandoned when they do not fit the facts.

Scientific Analysis

Goal Methods

Describe behavior Naturalistic observation, Surveys, Case studies

Predict behavior Correlational methods

Explain behavior Experimental methods

Change & control behavior Apply findings

What is a Theory?

A set of related statements that explains a variety of occurrences (Kantowitz)

An interrelated set of concepts used to explain a body of data and make predictions about future expts (Stanovich)

A statement of the probable relationships among a set of abstract variables (Martin)

A set of assumptions about the causes of behavior and the rules that specify how the causes operate (Bordens).

Theories - Properties

Theories help organize large amounts of data.

Theories generate hypotheses (predictions).

Theories help to better understand the world -- we hope to apply (generalize) to new, unstudied situations.

Theories are subjected to empirical test and retained, modified, or rejected.

Induction and Deduction

Theory

Prediction

Observations

ModifyTheory

Deduction

InductionIf observation were complete, we wouldn’t need theory. But observation can never include all facts.

Falsification Approach

It isn’t enough to show that facts support a theory – the same facts can support different theories, so which is true?

If a theory is not supported by data, it must be false and can be abandoned. Popper proposed that we learn more about

truth by falsifying incorrect theories than supporting theories.

Knowledge advances by testing and falsifying alternative explanations in successive studies.

Theories - Evaluation

Does the theory cover everything it should? Is it concise? Is it clearly expressed? Do all the bits of the theory hang together? Can the theory be tested? Is there evidence to support the theory? Does the theory help us think in new and

interesting ways?

Intervening variables

Abstract concepts that link the IV and DV Add to the efficiency of theorizing “Thirst” example from book is an excellent

example! Sometimes called “constructs.”

Hours of deprivation Rate of bar pressing

Hours of deprivation Rate of bar pressingThirst

Foxes versus Hedgehogs

The fox knows many things – generalists Multidisciplinary, tolerant of complexity,

adaptable, cautious (probabilistic), empirical (rely on observations).

The hedgehog knows one big thing – specialists Focused on a few great problems, stalwart

(sticks to the same approach), order-seeking, confident, ideological (theory-driven).

Science needs both! Foxes forecast better.

Psychology and the Real World

Applied research -- solves a specific problem. Basic research – conducted to answer

questions arising from curiosity, to advance understanding of a phenomenon.

Generalization – taking findings from the lab into real-world contexts. The extent to which this can be done varies.

Human factors, engineering psychology, and other applied fields.