1chp9 Flashcards
3 properties of a well designed experiment
1: vary at least one independent variable2: ensure initial equivalence of participants 3: control al extraneous variables
3 types of independent variables
environmental manipulations - manipulating aspects of the research setting instructional manipulations - variation in instructions to participantsinvasive manipulations - manipulating conditions in a participant’s body, ex stimulation, surgery, or drugs
pilot test
initial test with some participants to ensure that the different levels of independent variable are different enough to be detected by participants.are these two levels of lights different enough to be perceptible or significant?
manipulation check
question during an experiment designed to determine whether the independent variable was manipulated successfully. like, did the participant notice the light was brighter in this condition compared to the participants in other conditions where the light was dimmer?
subject/participant variables
things we cannot manipulate but vary, like the gender of a participant
simple random assignment
every participant has an equal probability of being placed in any experimental condition
matched random assignment
- researcher obtains participant scores on a measure known to be relevant to outcome of experiment (typically a pretest measure of the dependent variable)2. participants are ranked from highest to lowest3. creates clusters based on the number of conditions in the experiment. for ex, 2 highest scoring would be split into condition a and condition b. next 2 highest scoring would be split as well. all the way to bottom scoring
randomized groups design
simple random assignment or matched random assignment
between-groups design
interested in behavior BETWEEN groups of participantsas in participants in condition a versus those in condition b
within-subjects design
.each participant experiences all conditions or all levels of independent variable.don’t have to worry about randomizing, because no differences between conditions b/c all conditions experienced by each participant.has more power!.subject to order and carry over effects tho
order effects
behavior affected by the order in which they participate in the various conditions of the experiment.three types: practice, fatigue, sensitization.
practice effects
performance improves because complete the dependent variable several times.like if you do a simple memory test, they’re going to improve at it each subsequent time!
fatigue effects
participants become bored, tired, or less motivated as experiment progresses.may perform least well on experimental condition they receive last
sensitization
after completing dependent variable several times, participants may begin to realize what the hypothesis of experiment is, then start to respond differently!.aka they become sensitized to the purpose of the experiment
counterbalancing
guards against order effects.present levels of independent variable in different orders to different participants