PSY200-Exam #3 materials

Ch.8-10

Staged Manipulation

Stage events during the experiment in order to manipulate the independent variable

Confederate

Appears to be another participant in an experiment but is actually part of the manipulation

Strength of manipulation

A strong manipulation maximizes the differences between the two groups and increases the chances that the independent variable will affect the dependent variable. 

Self-reports 

Can be used to measure attitudes

Behavioral measures

Direct observations of behaviors

Physiological measures

Recordings of responses of the body (MRI, EMG, EEG)

Ceiling effect

A task so easy everyone does well regardless of the conditions that are manipulated

Floor effect

A task so difficult that hardly anyone can perform well

Demand Characteristics 

Any feature of an experiment that might inform participants of the purpose of the study 

Placebo group

Group that receives a pill or injection an inert harmless substance

Expectancy effects

May occur whenever the experimenter knows which condition the participants are in

Single-blind experiment

Participant is unaware of whether a placebo or the actual drug is being administered

Double-blind experiment

Neither the participant nor the experimenter knows whether the placebo or actual treatment is being given. 

Pilot study

Researcher does a trial run with a small number of participants 

Manipulation check

Attempt to directly measure whether the independent variable manipulation has the intended effect on the participants.

Factorial designs

Experimental designs with more than one independent variable

Main effect

The effect of each independent variable taken by itself

Interaction

If there is an interaction between two independent variables

Simple main effects

Examines mean differences at each level of the independent variable

Mixed factorial design

Use both independent groups and repeated measures procedures (Between+Within)

Confounding variable

A variable the varies along with the independent variable

Internal validity

When results of an experiment can confidently be attributed to the effect of the independent variable

Attrition/Mortality

The dropout factor in experiments

Between-subjects design

Participants are randomly assigned to the various conditions so that each participants in only one group

Within-subjects design 

All participants are in all conditions

Random assignment 

The decision to assign an individual to a particular condition is completely random

Order effect

The order of presenting the treatments affects the dependent variable 

Practice effects

Performance on the second task might improve merely because of the practice gained

Fatigue effect

Performance from the first to the second condition as the research participant becomes tired.

Carryover effect

Effect of the first treatment to carry over to influence the response to the second treatment. 

Matched pairs design

The goal is to first match people on a participant variable such as age or personality trait.