Quantitative psychology

Karl Popper came up with emprical falsifiability as a necessary criterion for scientific theories. Theories that cannot be falsified are theories such as psychoanalysis and "intelligence design". Necessary but not sufficient. Some things are hard to scientifically prove.

These assumptions are central to the scientific study of behaviour.

Behaviour is not purposeful:

 - not random

 - it has a complex system of cause

 - Behavioural events can be understood as sequences of causes and effects.

Behaviour is understandable

 - In principle: comprehensive thoeryof behaviour is possible.

Description

 - Social, Individual, Cognitive, Neural

Explanation

 - Identity factors cause behaviour

 - Identity mechanisms and processes that underlie behaviour

 - Avoid pseudo-explanation (independent verification of cause is essential)

Control

 - Manipulating cause affects behaviour

 - Correlation is not causation

 - Causality and interventions study designs.

- Hypothesis - a formally stated expectation about behaviour that defines the purpose and goals of a study.

 - It is a prediction about the studies outcome.

 - This is an essential component of psychology.

 - Statistical techniques are used extensively for hypothesis testing.

Causal - postulates a particular causal influence - cause and effect

Descriptive - Postulates particular characteristics of behaviour without reference to causation.

Two-tailed - direction of difference stated - more general

One-tailed - direction of difference is stated.

Falsifiable - tests can show that hypothesis is incorrect

Precise - Terms must be clearly defined

Rational - possibly true, given current understanding

Parsimonious - simple as possible and new concepts should only be introduced when necessary.

- Observation ofothers or introspection

- Existing research - original hypothesis is derived from a previous study or the resting of a previously tested hypothesis.

- Theory - logically organised set of proposals that defines, explains and organises our knowledge about significant aspects, or parts of behaviour.

1) Form hypothesis from theory, model or observations.

2) Design a study to observe behaviour.

3) Derive predictions

4) Conduct study and test predictions

5) Confirm or reject hypothesis

6) Modify theory (if necessary)

7) Repeat

1) Theory - "sex steroid hormones can prevent age-related cognitive decline"

2) Hypothesis - higher oestrogen and testosterone levels in older people should correlate with better memory test scores.

3) Experiment - conduct study, collect data and test predictions/

4) Conclusions - oppposite effects found: hypothesis wrong, thus theory is not supported. Reject or refine theory.

- Scientific research provides evidence

- Evidence should be

      - Empirical - based on observation

      - Objective - minimise personal interpretations and bias

      - Systematic - obtained in methodological fashion.

      - Controlled - elimination of intended, extraneous influences.

Central feature of experimental research: researcher systematically manipulates one variable and then measures another variable.

Used for testing causal hypothesis - e.g. A causes B

Rationale: if A changes B, then manipulation of A should change B.

A null hypothesis is where there is no effect.

Often, the null hypothesis is the opposite to the research hypothesis.

Rationale: we can never prove general emprical statement to be true, but we can prove such statement to be false.

Therefore, we can attempt to obtain evidence for the research hypothesis by proving that its opposite is false.

If statistical test leads to rejections of the null hypothesis then there are no implication for truth of the research hypothesis.

Therefore, we can only gain knowledge by rejecting the null hypothesis.

Researchers can actively manipulate a variable to which subjects are exposed by the researchers.

IV is the variable manipulated.

A condition is a specific amount or quality of the IV that is applied to subjects.

Particioant variables: naturally occur and vary, they cannot be controlled.

Experimenter/manipulated variables - manipulated by the researcher.

DV is the subjects response in each condition to the IV, the measured variable.

Control variables are held constant or "corrected for"

Variables that potentionally influence results, but are not of direct interest.

Can relate to subject, experimenter, environment etc.

Variables that potentionally influence results, but are not of direct interest.

Can relate to subject, experimenter, environment etc.