Chapter 2
About scientific methods applied to psychology
Clever Hans
Horse with some ‘human knowledge’ is NOT scientific
undermined by Oskar Pfungst
he found out the horse recognized visual signals (small head noddings)
3 essential ‘bricks’ in science:
1. Facts: objective observation is true
2. Theory: idea to (1) explain existing facts and (2) make predictions
3. Hypothesis: prediction about new facts that is made from theory
Lessons learned from Clever Hans:
1. The value of scepticism
Try not to prove correct, try to prove wrong
The simpler the explanation, the better
2. The value of careful observations under controlled conditions
3. The problem of observer-expectancy effect
Unintentionally communicating expectations
Unintentionally doing what the expert expects
Research Strategies
3 ways to categorize research strategies:
1. Research design
Experiments, correlational studies, descriptive studies
2. Setting
in which the experiment is conducted
3. Data-collection method
Self-report and observation
By varying these 3 you’ll have different research
Research Design
to test a hypothesis
1. Experiments
o Experiment : a procedure in which a researcher systematically manipulates variable
(while keeping all other variables constant!)
Most direct and conclusive approach
o Independent variable : the variable that is hypothesized to cause some effect on
another variable
o Dependent variable : the variable that is hypothesized to be affected
Mostly: dep. Variable: behaviour indep. Variable: other factors
, Subject of the study = the people or animals that are studied
Two types of experiments:
1. Within-subject experiments
o the subject(s) are tested in each condition of the independent variable
2. Between groups experiment
o the manipulation of the independent variable are applied to different groups of
subjects
always randomly assign the subjects!
2. Correlational Studies
when experiments can’t be conducted (for ethical or practical reasons)
Correlational study : a study in which the researcher doesn’t manipulate variables, but
observes or measures two already existing variables to find relationships.
- can tell something about the relationship between two variables
Studies correlation, NO CAUSATION
3. Descriptive studies
= when the aim of the research is to describe behaviour of an individual (or set of
individuals) without looking for relationships between variables.
Research Settings
2 research settings:
1. Laboratory study = any study in which participants are brought to a specific area where the
conditions are in control of the researcher.
2. Field study = any study in which the researcher doesn’t have control over the conditions.
This can be at workplaces, at home, or natural environment.
Laboratory study Field study
Controlled conditions Uncontrolled conditions
Divergent behaviour possible The regular behaviour
o Subject knows from it o Subject has no idea
Experiments Correlational studies
Descriptive studies
Data-collection Methods
1. Self-report method = procedure in which people are asked to rate or describe their own
behaviour or mental state in some way.
o Questionnaires, interviews
o Introspection = type of self-report personal observations of thoughts, feelings etc.
Highly subjective
About scientific methods applied to psychology
Clever Hans
Horse with some ‘human knowledge’ is NOT scientific
undermined by Oskar Pfungst
he found out the horse recognized visual signals (small head noddings)
3 essential ‘bricks’ in science:
1. Facts: objective observation is true
2. Theory: idea to (1) explain existing facts and (2) make predictions
3. Hypothesis: prediction about new facts that is made from theory
Lessons learned from Clever Hans:
1. The value of scepticism
Try not to prove correct, try to prove wrong
The simpler the explanation, the better
2. The value of careful observations under controlled conditions
3. The problem of observer-expectancy effect
Unintentionally communicating expectations
Unintentionally doing what the expert expects
Research Strategies
3 ways to categorize research strategies:
1. Research design
Experiments, correlational studies, descriptive studies
2. Setting
in which the experiment is conducted
3. Data-collection method
Self-report and observation
By varying these 3 you’ll have different research
Research Design
to test a hypothesis
1. Experiments
o Experiment : a procedure in which a researcher systematically manipulates variable
(while keeping all other variables constant!)
Most direct and conclusive approach
o Independent variable : the variable that is hypothesized to cause some effect on
another variable
o Dependent variable : the variable that is hypothesized to be affected
Mostly: dep. Variable: behaviour indep. Variable: other factors
, Subject of the study = the people or animals that are studied
Two types of experiments:
1. Within-subject experiments
o the subject(s) are tested in each condition of the independent variable
2. Between groups experiment
o the manipulation of the independent variable are applied to different groups of
subjects
always randomly assign the subjects!
2. Correlational Studies
when experiments can’t be conducted (for ethical or practical reasons)
Correlational study : a study in which the researcher doesn’t manipulate variables, but
observes or measures two already existing variables to find relationships.
- can tell something about the relationship between two variables
Studies correlation, NO CAUSATION
3. Descriptive studies
= when the aim of the research is to describe behaviour of an individual (or set of
individuals) without looking for relationships between variables.
Research Settings
2 research settings:
1. Laboratory study = any study in which participants are brought to a specific area where the
conditions are in control of the researcher.
2. Field study = any study in which the researcher doesn’t have control over the conditions.
This can be at workplaces, at home, or natural environment.
Laboratory study Field study
Controlled conditions Uncontrolled conditions
Divergent behaviour possible The regular behaviour
o Subject knows from it o Subject has no idea
Experiments Correlational studies
Descriptive studies
Data-collection Methods
1. Self-report method = procedure in which people are asked to rate or describe their own
behaviour or mental state in some way.
o Questionnaires, interviews
o Introspection = type of self-report personal observations of thoughts, feelings etc.
Highly subjective
