ch 8 Flashcards
(19 cards)
How does random assignment influence what participants experience/do during between-subjects experiments?
Random assignment is an important means of control in an experiment for between-subjects experiments.
Example for how does random assignment influence what participants experience/do during between-subjects experiments?
in a between-subjects manipulation, randomly assigning participants to different groups controls for individual differences across the groups that might affect the data.
For within-subjects experiments understand how a sample is assigned to different levels of the IV and
controlling order effects in within-subjects experiments
The order in which they receive these tasks can certainly affect the outcome of the study. If participants receive an easy task first and then a difficult task, they are likely to view the difficult task as more difficult than they would if they had received it before the easy task.
What type of validity is affected by random assignment?
Internal Validity
Pros of Between-subjects Designs
Prevents carryover effects of learning and fatigue. Shorter study duration
Cons of Between-subjects Designs
Needs larger number of participants to generate any useful and analyzable date.
Pros of Within-subjects Designs
Requires smaller sample size as each participants provides repeated measure for each treatment condition
Cons of Within-subjects Designs
Time-related effects, can influence the outcome
Matched design
A between-subjects experiment that involves sets of participants matched on a specific characteristic with each member of the set randomly assigned to a different level of the independent variable
How is matched design different from a typical between-subjects experiment?
participants are matched on a characteristic that may contribute to group differences and between experiences only one level
Why would a matched design be used in a study (i.e., what are researchers trying to accomplish with this type of design)?
It means that the researchers do not need as many participants as in other designs
How does counterbalancing and within-subjects process work
To solve the problem of order effects for within-subjects manipulations, a researcher typically uses counterbalancing of the order of the levels within the study. This means that different groups of participants receive different orders of the levels of the independent variable.
Example of how counterbalancing and within-subjects process work
To illustrate this issue, consider a within-subjects experiment with three conditions: A, B, and C. There are six possible orders in which participants can experience these three conditions: ABC, BCA, ACB, CBA, CAB, and BAC. To fully counterbalance these three conditions, you would need six different orders of the conditions and numbers of participants in multiples of six in order to make an equal number of participants randomly assigned to each of the six possible orders of conditions.
Latin Square
Partial counterbalancing technique where the number of orders of conditions used is equal to the number of conditions in the study
Why might latin square be used in a research study and what is it used for?
If there are four conditions it makes counterbalancing difficult so latin square is used for that. (Sqaure has four corners)
Need to be able to identify the type of experiment (i.e., between-subjects or within-subjects experiment) if given an example and/or asked to provide your own examples
Provide example
Cognitive example
includes the study of basic processing of information from the world around us.
Example: Cognitive psychologists study memory, perception, language processes, and decision making. Much of the research in these areas is focused on understanding factors that influence these processes and how they operate. Thus, experiments are a very common research design for cognitive psychologists.
Biological example
Investigates the role of biological factors in behavior.
- Thus, experiments are often employed in this area of psychology to determine causal relationships between biology and behavior. In many cases, participants are asked to perform different tasks while brain function that corresponds to these tasks is recorded to better understand where brain activity occurs for different behaviors.
Social example
Examine the effects of social factors on different types of behaviors.
- subjects were randomly assigned to “pain” and “no pain” groups. The subjects in the pain group were asked to submerge their hand in icy water for as long as possible to complete a task sorting metal balls from the bowl of water into containers and then to hold a squat position against the wall for as long as possible. Subjects in the pain group rated their bonding higher than the subjects in the no pain group.
