Quiz: Ackerman (2013)
The following quiz assesses students' ability to think critically about a piece of research. The study examines the role of cortisol in memory.
Please see the file below to give your students a paper copy.
Student copyA shareable student version of this page can be accessed here.
The quiz
Ackerman et al. (2013) had a sample of 1225 participants (812 women and 413 men) between 18 and 35 years old (mean age = 22.49 years, SD = 3.59 years). Of the 812 women participating in the study, 429 were taking hormonal contraceptives, whereas 383 were not. Participants were students or employees from the Basel area who were paid for participation. They did not take any medication (except hormonal contraceptives) and reported no neurological or mental illness.
The researchers wanted to see how changes in one's naturally occurring cortisol levels affected memory performance.
Individuals performed a memory task in which they were asked to rate a series of 72 images as emotionally positive, negative, or neutral. After ten minutes - and then again the next day- they were asked to recall as many images as possible; there was no time limit. The participants' cortisol levels were measured via saliva samples before the images were shown, before being asked to recall, and then again after recall.
The researchers found that the cortisol level itself was not as important as the change in cortisol during memory retrieval. The greater the increase in cortisol from the baseline when retrieving information, the lower the level of recall. This explains why students with higher stress responses during exams will have more difficulty recalling information.
Questions
- Which design was used in this study? What were the independent and dependent variables?
- Comment on the internal validity of this study.
- Explain how one potential participant variable may have affected the study.
- Explain one ethical consideration in this study.
- Comment on the ecological validity of this study.
- Comment on the construct validity of this study.
Assessing responses
Each response may earn a maximum of three marks, totaling 18 marks.
1. Which design was used in this study? What were the independent and dependent variables?
Sample student response: The study uses an independent samples design. The independent variable is the participants' natural level of cortisol. The dependent variable is the number of images that were recalled.
Assessment: 1 mark for correctly identifying the design. 1 mark for identifying the IV. 1 mark for identifying the DV.
2. Comment on the internal validity of this study.
Sample student response: The study is not a true experiment because the cortisol level is naturally occurring and not manipulated by the researcher. Internal validity allows the researcher to determine whether one's cortisol level affects one's ability to recall the images. The study is conducted in the students' natural environment, and there is a one-day difference between when they first see the images and then recall them. Confounding variables could occur during that day that may influence the recall of the photos.
Assessment: 1 mark for a definition of internal validity. 2 marks for a clear justification of their position linked directly to the study.
Common errors: One common error is to say that this is a field experiment, so it has "no internal validity." This is not correct. The goal of the "comment" command term is for students to show that it is not a "yes" or "no" response but that these concepts are complex.
3. Explain how one potential participant variable may have affected the study.
Sample student response: Participant variables may play a role in this study because the experiment uses an independent samples design. One important variable is their memory capacity. Different people have different levels of skill regarding the recall of visual information. Some people who lack this skill or have very strong memory skills may distort the overall performance of their condition. Participant variables may compromise the study's internal validity and not allow for a causal relationship to be determined.
Assessment: 1 mark for understanding the term "participant variable." 1 mark for identifying an appropriate participant variable. 1 mark for explaining how it may impact the study. Other appropriate variables include their daily stress level, age, or education level (for those who are members of the community but not students).
Common errors: Participant variables are one type of confounding variable. Some students may write about demand characteristics, but this would not earn credit.
4. Explain one ethical consideration in this study.
Sample student response: One ethical consideration in this study is informed consent. The researchers would have to explain the experiment's aim and the nature of the experiment. They should know how cortisol will be measured, the time required for the experiment, and the ethical standards - e.g., they may withdraw at any time. The study has no reason for deception, so fully informed consent should be obtained. It is also important that the anonymity of their data is guaranteed when consent is obtained, especially as they are being asked to share whether they are taking birth control.
Assessment: 1 mark for identifying and defining an ethical consideration. Up to 2 marks for linking the ethical consideration to the study.
Common errors: Many students gravitate to "undue stress or harm." There is no undue stress or harm in this experiment. The stress they may experience is no different from daily stress experiences. In addition, the cortisol rise does not cause stress. Such responses are superficial and do not attract high marks.
5. Comment on the ecological validity of this study.
Sample student response: This study takes place in the participants' naturalistic environment—a classroom. For the students, this environment would be familiar. However, the task's ecological validity is compromised because it lacks ecological validity. Being asked to memorize 72 images in quick succession is not a task that we face daily.
Assessment: 1 mark knowledge of the meaning of ecological validity. Up to 2 more marks for a clear link to the study.
Common errors: Students often write that the sample is representative or not - and that this affects the ecological validity. This is incorrect. This affects the external validity - which is based on both ecological and population validity.
6. Comment on the construct validity of this study.
Sample student response: The researchers want to know whether one's cortisol level affects their ability to recall a series of images. As they are being asked to "recall" the images, it is questionable how the researcher will "count" whether an answer is correct. It would be important to have more than one researcher count the correct responses to establish inter-rater reliability. In addition, it is difficult to conclude that this study "explains why students with higher stress responses during exams will have more difficulty recalling information." The information in these photos is irrelevant to the participants and is solely visual. This does not reflect the type of learning students do for exams or the kind of information that they are asked to remember.
Assessment: 1 mark for a definition of construct validity (or a clear indication of understanding). 1 mark for identifying the variable that may have or lack construct validity. 1 mark for explaining why this variable may lack or have construct validity.