Developmental Research MethodsTopic 10: Experimental Ecology?

04/10/2023CEDP 321/322 Ryan Sain, Ph.D. 1

Experimental EcologyThe experiment is an interaction

between the experimenter, subjects and environment

Laboratory observation vs. external observation◦Mothers and play

Ecological validity◦How much does the context influence

the findings?

Experimenter effects

Bias in data collection◦Maskelyne and

Kinnenbrook This is a case of

the PERSONAL EQUATION

Operational definitions help this

Multiple observers

Interrater reliability

Bias in data errors• Favor own hypothesis• Morton – intelligence across races• Selection bias• Did not know he was doing this

• Sometimes its not so innocuous• Burt - manipulation of data to support his

theory. (intelligence is a result of genetic factors)

Biased interactionsExperimenters can treat various

subjects differently◦Attractive, male, female, etc.

Use scripts

◦We also bias people by hinting at what the goals of our research are. Subjects will then try to change their

behavior to match or not match our goals.

Reducing biasUse multiple experimentersBlinding

◦Blind the subject◦Blind the experimenter or both

Subject factorsProblems with interpreting results

come from subjects too.

These are huge issues and cloud the experiment in the forms of threats to validity.

Hawthorne effectA thing observed

changesLadies working at a

production plant◦ Increased

productivity in general – even when they should not have.

◦ They were reacting to being part of the study and felt special as a result – and increased productivity.

Placebo (expectancy)Just the act of taking something may

cause you to change on whatever factor it is.◦Headaches, etc.

You can control this by taking measurements BEFORE you start the placebo condition to see if they change in the placebo condition as well.◦Mixed design

You can also control for this through blinding.

Demand CharacteristicsParticipants response is

influenced by the experimental setting by themselves.

They have an idea about how to behave in a given situation◦They then match their behavior to

that idea.◦Alcohol, marijuana, etc.

Deception helps control for these.Distractors help control for these.

Cultural bias

Our bias may be the culture itself◦African Americans and psychotherapy

Rules for including minorities and women in research

ParadigmsChanging the way we see the

world allows us to ask new questions about it.

New technologiesNew discoveries.