Chapter 9 Flashcards
3 essential properties of welldesigned experiemnts
- At least one independent variable is manipulated
- Participants are randomly assigned to conditions
- All extraneous variables are controlled for
Experimental conditions
Differnt levels of the independent variable
3 types of independent variables
- Environmental
- Instructional
- Invasive
Environmental and example
Modify something int he environment
Ex. Temperature
Confederates
Actor; particpants dont know that the person is in on the experiment
Instructional w/ exs
Differnt experimental conditions recieve differn instructions of interventions
Ex. Recieveing the easy, hard, or neutrally indicated difficulty test
Invasive
Creating physical changes in a perticipants body through physical stimilation
Ex. Administration of drugs
Experimental group
Recieves the active level of IV
Control group
Recieves the placebo IV or no IV at all
Participant variables and examples
Variables that are not manipuated and are therfor not considered true IVs
Exs. Sex, age, birth order
Experimentation determines _______
Causality
Simple random assignment
Any participant has an equal proablity of being placed in any of the experimental conditions
Matched random assignment
Participants are grouped based on some relevant charcateristic and then randomyl selected from both groups for either recieving or not recieveng the IV
Repeated measures design
(Within subjects design) Each subject experimences all leves of the IV
Pros and cons of repeated measure designs
Pro: increased power
Con: practice effects
Counterbalancing
Present conditions in differnt orders to different participants to reduce practice effects
Internal validity
The degree to which we are confident that the changes int he IV are causing chnages in the DV
Internal validity of an experiment is increased by ______.
Increasing experimental control such as eliminating confounds
Experimental expectancy effects, how it disorts results, and how to eliminate
- Researchers typicially have some ideas how partipants will respond
- Can distrot results by affecting how reasercher interprets observed behaivor
- Eliminate with double-blind procedure
Demand charcteristics, how it distorts results, how to eliminate
- Participants figure out how they should behave
- Can distrot results by influencing how particiapnts act
- Eliminate with double blind procedure
Placebo effects, how it distorts results, how to eliminate
1physiological or psychological change as a result of the belief a change will occur
- Treatment might be confounded by participants knowlege they are recievibg treatment
- Eliminate with use of placebo control group
External validity
Extent to which the results of a study can be generalized
Experimenter tend to favor ______ validity over _______ validity.
Internal, external
Advantages and disadvantages of web based experimental research
Ad:
-can obtain large sample sizes
-fewer resources needed
-can recruit more diverse samples
-easy to target recruitment efforts
-may be less susceptible to social desirability bias
Dis:
-difficult to identify and control the nature of the sample
-cannot control study setting
- participants may not complete the survey
-not ideal for all research paradigms
Power
The ability to detect the effects of the independent variable
Advantages and disadvantages of a within subjects design
Ad:
-more power than between subjects
Require fewer participants
Dis:
- order effects
- carryover effects
Within subjects design
Particiapnts serve in all experimental conditons and their behaivor is measured for each conditon
Order effects
Particpants behivor is effected by the order in which they participate int he experimental conditons
3 types of order effects
- Practice
- Fatigue
- Sensitization
Sensitization
Participants uncover the true purpose of the experiment and begin to react differntly than they did before they know the purpose.
Carryover effects
Occure when the effect of a particulare treatment condition persists even after the treatment ends.
3 components of total variance
- Treatment variance
- Confound variance
- Error variance
Systematic variance is made up of _____ and _______
Treatment, confound
Unsystematic variance is made up of _____ variance.
Error
5 common threats to internal valididty
- Miscellaneous design confounds
- History
- Pretest sensitization
- Differential attrition
- Biased assignment of participants to experimental conditons(selection threat)
Attrition
The loss of participants during a study
5 Sources of error variance
- Individual differnces
- Transient states
- Enviromental factors
- Differential treatment
- Measurment error
3 types of dependent variables
- Observations of behaivor
- Self-report
- Ps\hysiological reactions
