Experimental Control
Experimental control is the fundamental process by which researchers hold extraneous variables constant throughout a study. Because extraneous factors—such as individual participant differences or situational contexts—are likely to have an unintended effect on the dependent variable, they make it difficult to separate their impact from the true effect of the manipulated independent variable. By actively controlling these outside variables and preventing them from fluctuating across conditions, researchers can isolate the independent variable and confidently attribute any changes in the dependent variable to the experimental manipulation.
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Research Methods in Psychology - 4th American Edition @ KPU
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Participant Variable
Situational Variable
Task Variable
Experimental Control
Experimenter's Sex as an Extraneous Variable
Standardizing the Procedure
Experimenter Expectancy Effect
Example of Extraneous Variables: Expressive Writing Experiment
Confounding Variable
Internal Validity
In the context of an experiment, what is an extraneous variable?
In a study examining whether caffeine improves focus, the amount of sleep a participant had the night before would be considered an extraneous variable if it varies between participants and could potentially influence the results.
In psychological research, factors other than the primary ones being studied can often influence the results. Match each research study with the specific factor that would act as an extraneous variable in that scenario.
A researcher conducts a study to see if 'Bright Lighting' (the factor being tested) improves 'Reading Speed' (the performance being measured). However, the group in the bright light reads an interesting novel, while the group in the dim light reads a technical manual. Arrange the following statements to represent the logical sequence of how this extraneous variable (Topic Interest) creates ambiguity in the study's results.
True or False: In experimental research, an extraneous variable is defined as any factor that varies within the context of a study other than the specific variables being investigated.
In an experiment, why does the presence of an extraneous variable that varies within the study make it difficult to draw clear conclusions about the relationship between the independent and dependent variables?
When a researcher evaluates the validity of a claim that one factor caused a change in another, they must determine if any additional factors fluctuated during the study. A factor that varies in the context of the study other than the ones being specifically investigated is known as a(n) _____ variable; its presence requires the researcher to judge the study's conclusions as inconclusive because the true cause of the results cannot be isolated.
A researcher is conducting an experiment to see if a new mnemonic strategy improves memory recall. Match each element of this research study to its correct classification.
A researcher designs an experiment to measure the effect of cell phone use on reaction times. If the participants' age varies throughout the study and potentially affects reaction times, the researcher must recognize age as a/an _____ variable because it is a factor other than the independent and dependent variables that could introduce competing influences.
Order the steps a researcher should take to evaluate and manage potential threats to internal validity from factors outside the primary hypothesis.
Define the term 'extraneous variable' in the context of experimental research. In your definition, explain the primary challenge that fluctuating extraneous variables present to researchers who are trying to evaluate the relationship between an independent variable and a dependent variable.
Based on the concept of extraneous variables, diagnose why the room temperature and lawnmower noise are classified as extraneous variables in this study, and explain how these fluctuating factors affect the researcher's ability to detect the true effect of the cognitive training exercise.
A researcher is conducting an experiment to evaluate the effect of a new distraction-free interface on task completion speed. However, the researcher realizes that the brightness of the computer monitors fluctuates across different testing stations. Apply the concept of experimental control to manage this monitor brightness extraneous variable, and explain how this application improves the study's design.
Independent Variable
Dependent Variable
Extraneous Variable
Experimental Manipulation
Within-Subjects Experiment
Between-Subjects Experiment
Pilot Test
Experimental Control
What is the primary purpose of conducting an experiment in psychological research?
A researcher surveys 200 university students and finds a strong positive relationship between the number of hours spent studying and final exam scores. Because the relationship is statistically significant, the researcher can conclude that more studying causes higher exam scores.
A researcher is conducting an experiment to determine if listening to classical music while studying causes higher test scores compared to studying in silence. Match each element of this study to its role in the experiment.
A researcher is moving beyond simply observing a relationship between two variables and wants to determine if that relationship is causal. Arrange the logical stages of an experiment to show how the design isolates a cause and supports a causal conclusion.
A researcher is tasked with constructing a new study to determine if 'viewing nature-themed videos causes a reduction in physiological stress levels.' Which of the following research designs should the researcher create to satisfy the requirements of an experiment and support a causal conclusion?
Any psychological research study that utilizes statistical analysis to support its conclusions is classified as an experiment.
A researcher claims that a specific exercise program is the reason for improved mental health, but their study did not involve an actual intervention or controlled manipulation. To evaluate the validity of this 'cause-and-effect' claim, a critic would argue that the study fails to meet the requirements of an experiment and thus cannot support _____ conclusions.
A student is categorizing different components of a research project. Match each concept related to the project's design to its correct definition based on the characteristics of an experiment.
A psychologist analyses a study's methodology and notes that while it demonstrates a relationship between two variables, it does not use a design capable of establishing causality. To successfully determine if this relationship is causal in nature, the researcher must design a(n) _____.
Evaluate the design of a psychological study to determine if it can support a causal claim. Order the steps of this evaluation from the first logical check to the final determination.
Define an experiment in psychological research and state how it supports its conclusions.
Based on the definition of an experiment, explain how the psychologist's proposed experiment differs from their initial observation in terms of the relationship it aims to establish, and what method they must employ to support their final claims.
A researcher plans to test a new memory-enhancing drug. Apply the definition of an experiment to explain what type of relationship they are testing for between the drug and memory, and what is required to support their conclusion.
What is the primary purpose of conducting an experiment in psychological research?
In psychological research, any study that uses statistical analysis to identify a meaningful relationship between two variables is classified as an experiment.
A cognitive psychologist wants to determine whether listening to classical music while studying directly improves memory retention. Because the goal is to establish if the relationship between these two variables is causal in nature, the researcher must conduct an ____.
Analyze the core components of a psychological experiment. Match each research action or description to the specific part of an experiment's definition that it best illustrates.
A peer reviewer is evaluating a research manuscript to determine if it meets the core criteria of a psychological experiment. Arrange the steps of this evaluation process in the correct logical order, from the initial identification of elements to the final judgment of the study's methodology.
Which of the following is defined as a specific type of research study designed to determine if a meaningful relationship between two variables is causal in nature?
Based on the core definition of an experiment in psychological research, what specific type of conclusion does this method allow researchers to draw that other research methods typically do not?
A researcher wants to understand how sleep quality affects memory recall in young adults. Based on the core definition of a psychological experiment, which of the following study designs best represents this method?
A research team investigates the relationship between screen time and sleep quality. Study A records the daily screen time and sleep duration of participants over a month, finding a strong negative relationship. Study B assigns participants to either a 'no screen time before bed' group or a 'two hours of screen time before bed' group, then measures their sleep quality. Based on the core definition of psychological research methods, why does Study B qualify as an experiment while Study A does not?
A researcher observes that students who naturally choose to sit in the front row of a lecture hall score higher on exams than those in the back row. The researcher runs a statistical analysis comparing the two groups and publishes a paper claiming, 'Sitting in the front row causes students to achieve higher exam grades.' As a reviewer evaluating this research based on the core definition of a psychological experiment, which is the most accurate judgment of the researcher's methodology and conclusion?
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What is the primary purpose of experimental control in a research study?
Match each component of experimental control with its specific role in a psychological experiment to demonstrate how researchers isolate causal effects.
A cognitive psychologist is studying the effect of word length on memory. To maintain experimental control, the psychologist ensures that all participants see the words on the same computer screen, at the same distance, and for the same duration of time.
A researcher is studying the effect of a new 'Focus App' on student productivity. To ensure that the app is the actual cause of any improvement, the researcher must apply experimental control. Arrange the steps of this process in the correct logical order to demonstrate how control isolates the independent variable.
The primary purpose of experimental control is to prevent extraneous variables from fluctuating across the different conditions of a study.
A researcher investigating a new study technique ensures that all participants take their practice tests in the same quiet room at the same time of day. Which statement best interprets the scientific rationale for this application of experimental control?
A researcher claims that a specific exercise program increases mental clarity, but they fail to hold the participants' daily caffeine intake constant across the different groups. Because the researcher did not maintain experimental control over this outside factor, a scientific evaluator would conclude that the researcher cannot make a valid causal _____ regarding the program's actual effect.
A cognitive psychologist is investigating how different lighting levels affect reading comprehension. Match each element of this study to the correct variable type or control function to show how the researcher isolates the causal effect.
In a study testing a new memory drug, the researcher tests the drug group in the morning and the placebo group in the afternoon. Because time of day was allowed to fluctuate across conditions, the researcher failed to maintain experimental control over this _____, making it difficult to isolate the true effect of the drug.
Arrange the steps in the logical order a researcher must follow to evaluate and establish experimental control in a study testing a new reading application.
Based on the concept of experimental control, define what this process entails and state its primary purpose. Additionally, identify the two broad categories of extraneous factors mentioned that can have an unintended effect on the dependent variable if not controlled.
Applying the concept of experimental control, explain why the researcher cannot confidently conclude that the study environment caused the difference in reading comprehension. Diagnose the specific extraneous variables that were allowed to fluctuate and explain how this failure prevents the researcher from isolating the independent variable.
A researcher is studying the effect of a new cognitive training app on memory recall. If they want to apply experimental control to the situational context of room temperature, what concrete action must they take, and why is this action necessary according to the concept of experimental control?