Exam 10: Introduction to Simple Experiments

In the study depicted in the figure above, how could a researcher transform the study into a within-groups design?

What is the primary difference between pretest/posttest designs and within-groups designs?

Explain why control variables are necessary in experiments and why they are not actually variables.

What is a design confound? What type of validity is threatened by design confounds, and how is it threatened? Explain why not all problems in a study are necessarily confounds.

When conducting an experiment, what is provided by the independent variable?

What is the difference between a posttest-only design and a pretest/posttest design? Provide both a benefit and a disadvantage of using a pretest/posttest design.

Which of the following phrases describes a manipulated variable?

Dr. Lonsbary is a cognitive psychologist who is curious about how mood affects memory. She recruited 60 high school students and divided them into three groups. Group A listened to a 5-minute piece of music intended to make them feel happy ("Happy" by Pharrell). Group B listened to a 5-minute piece of music intended to make them feel sad (a song titled "Home Is Such a Lonely Place" by Blink-182). Group C listened to no music and instead was asked to sit quietly for 5 minutes (thought to make them feel neutral). When a participant would come to her laboratory, Dr. Lonsbary would greet the participant and then ask him or her to roll a six-sided die. Participants who rolled a 1 or 2 were assigned to Group A. Participants who rolled a 3 or 4 were assigned to Group B. Participants who rolled a 5 or 6 were assigned to Group C. The participants were then given an unlabeled CD to listen to based on their group assignment. The CD contained either the song selection or 5 minutes of silence. They were then escorted into a different room, where they were greeted by a research assistant who conducted the experiment. The research assistant sat the participants in front of a computer screen and told them that a list of 25 words would be displayed on the screen. They were instructed to listen to the CD with headphones while trying to memorize the list of words. All participants were given the same list of 25 common words to remember (e.g., desk, gray, plane, car, mask). When 5 minutes had passed, the screen displayed a question asking them whether they felt happy, sad, or neutral. After the participant responded, a new screen was displayed asking them to type in all the words they could remember from the list of 25 words. All participants were given 3 minutes to type the words they remembered. Afterward, the participant was thanked and dismissed. In response to the mood question, a majority of Group A participants said they were happy, a majority of Group B participants said they were sad, and a majority of Group C participants said they were neutral in their mood. Dr. Lonsbary found the following results in response to the number of words remembered. Which of the following is a dependent variable in Dr. Lonsbary's study?

In the study depicted in the figure above, why might researchers have measured blood pressure twice?

All of the following are advantages of within-groups designs EXCEPT:

Dr. Phillips is a cognitive-developmental psychologist who studies how children learn mathematical principles. His current interest is in studying how children learn multiplication. He recruits 54 second-graders who have not yet learned how to multiply numbers to participate in his study. He is curious as to whether different teaching styles lead to better mastery of the subject. One condition (A) involves having students read a chapter on multiplication from their textbook. One condition (B) involves having students watch a video of cartoon characters explaining multiplication. One condition (C) involves having students being taught multiplication by a teacher. One condition (D) involves having students being taught multiplication by a fourth-grader. In all conditions, participants spend 30 minutes learning the fundamentals of multiplication and are then given the same 15-question multiplication test. The number of questions answered correctly is recorded. The data are below. Based on the results of his study, Dr. Phillips hopes to make a causal statement. Explain how his study does or does not meet the three rules of causation.

Dr. Lonsbary is a cognitive psychologist who is curious about how mood affects memory. She recruited 60 high school students and divided them into three groups. Group A listened to a 5-minute piece of music intended to make them feel happy ("Happy" by Pharrell). Group B listened to a 5-minute piece of music intended to make them feel sad (a song titled "Home Is Such a Lonely Place" by Blink-182). Group C listened to no music and instead was asked to sit quietly for 5 minutes (thought to make them feel neutral). When a participant would come to her laboratory, Dr. Lonsbary would greet the participant and then ask him or her to roll a six-sided die. Participants who rolled a 1 or 2 were assigned to Group A. Participants who rolled a 3 or 4 were assigned to Group B. Participants who rolled a 5 or 6 were assigned to Group C. The participants were then given an unlabeled CD to listen to based on their group assignment. The CD contained either the song selection or 5 minutes of silence. They were then escorted into a different room, where they were greeted by a research assistant who conducted the experiment. The research assistant sat the participants in front of a computer screen and told them that a list of 25 words would be displayed on the screen. They were instructed to listen to the CD with headphones while trying to memorize the list of words. All participants were given the same list of 25 common words to remember (e.g., desk, gray, plane, car, mask). When 5 minutes had passed, the screen displayed a question asking them whether they felt happy, sad, or neutral. After the participant responded, a new screen was displayed asking them to type in all the words they could remember from the list of 25 words. All participants were given 3 minutes to type the words they remembered. Afterward, the participant was thanked and dismissed. In response to the mood question, a majority of Group A participants said they were happy, a majority of Group B participants said they were sad, and a majority of Group C participants said they were neutral in their mood. Dr. Lonsbary found the following results in response to the number of words remembered. Which of the following is an independent variable in Dr. Lonsbary's study?

Generally, what is the main priority for experimental studies?

Dr. Phillips is a cognitive-developmental psychologist who studies how children learn mathematical principles. His current interest is in studying how children learn multiplication. He recruits 54 second-graders who have not yet learned how to multiply numbers to participate in his study. He is curious as to whether different teaching styles lead to better mastery of the subject. One condition (A) involves having students read a chapter on multiplication from their textbook. One condition (B) involves having students watch a video of cartoon characters explaining multiplication. One condition (C) involves having students being taught multiplication by a teacher. One condition (D) involves having students being taught multiplication by a fourth-grader. In all conditions, participants spend 30 minutes learning the fundamentals of multiplication and are then given the same 15-question multiplication test. The number of questions answered correctly is recorded. The data are below. Explain why Dr. Phillips cannot conduct a within-groups design.

Practice effects and carryover effects are examples of effects.

Random selection enhances validity and random assignment enhances validity.

Explain the difference between full counterbalancing and partial counterbalancing. Why would a researcher choose partial counterbalancing over full counterbalancing?

Dr. Lonsbary is a cognitive psychologist who is curious about how mood affects memory. She recruited 60 high school students and divided them into three groups. Group A listened to a 5-minute piece of music intended to make them feel happy ("Happy" by Pharrell). Group B listened to a 5-minute piece of music intended to make them feel sad (a song titled "Home Is Such a Lonely Place" by Blink-182). Group C listened to no music and instead was asked to sit quietly for 5 minutes (thought to make them feel neutral). When a participant would come to her laboratory, Dr. Lonsbary would greet the participant and then ask him or her to roll a six-sided die. Participants who rolled a 1 or 2 were assigned to Group A. Participants who rolled a 3 or 4 were assigned to Group B. Participants who rolled a 5 or 6 were assigned to Group C. The participants were then given an unlabeled CD to listen to based on their group assignment. The CD contained either the song selection or 5 minutes of silence. They were then escorted into a different room, where they were greeted by a research assistant who conducted the experiment. The research assistant sat the participants in front of a computer screen and told them that a list of 25 words would be displayed on the screen. They were instructed to listen to the CD with headphones while trying to memorize the list of words. All participants were given the same list of 25 common words to remember (e.g., desk, gray, plane, car, mask). When 5 minutes had passed, the screen displayed a question asking them whether they felt happy, sad, or neutral. After the participant responded, a new screen was displayed asking them to type in all the words they could remember from the list of 25 words. All participants were given 3 minutes to type the words they remembered. Afterward, the participant was thanked and dismissed. In response to the mood question, a majority of Group A participants said they were happy, a majority of Group B participants said they were sad, and a majority of Group C participants said they were neutral in their mood. Dr. Lonsbary found the following results in response to the number of words remembered. Prior to conducting the current study, Dr. Lonsbary asked her research assistant to use the same mood manipulation with a sample of 30 college students to determine if people's moods really did change after listening to the music. Running this preliminary study helps establish validity.

Dr. Phillips is a cognitive-developmental psychologist who studies how children learn mathematical principles. His current interest is in studying how children learn multiplication. He recruits 54 second-graders who have not yet learned how to multiply numbers to participate in his study. He is curious as to whether different teaching styles lead to better mastery of the subject. One condition (A) involves having students read a chapter on multiplication from their textbook. One condition (B) involves having students watch a video of cartoon characters explaining multiplication. One condition (C) involves having students being taught multiplication by a teacher. One condition (D) involves having students being taught multiplication by a fourth-grader. In all conditions, participants spend 30 minutes learning the fundamentals of multiplication and are then given the same 15-question multiplication test. The number of questions answered correctly is recorded. The data are below. Write a question you would ask of Dr. Phillips' study to interrogate each of the four validities.

Which of the following is an advantage of within-groups designs?