Chapter 83. Cross-sectional and Longitudinal Research

Learning Objectives

cohort
group of people born at the same historical time
longitudinal study
a type of research design in which the same individuals (or people from the same cohort) are tested at several different historical times
cohort effect
differences between age groups that are the result of generational differences in life experiences, not developmental changes
memory
the process of remembering information that has been learned
cross-sectional study
a type of research design comparing people of different ages who are tested at the same historical time
recall test
a method of measuring memory by asking participants to retrieve information that they had stored earlier
development
changes in a person’s thinking and behavior that typically accompany increased chronological age
recognition test
a method of measuring memory by showing participants the information and asking them to indicate whether it matches what they had stored earlier
Cross-sectional and Longitudinal Research
true
true
true
Rawpixel Ltd/Getty Images
Learning Objectives:

Contrast cross-sectional and longitudinal research designs.

Understand the cohort effect in developmental research.

Describe the age-related pattern of memory performance on recall and recognition tests.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

The image includes three different groups of people at different ages. The first group is 20 years old, the second group is 30 years old, and the last group is 40 years old.

1. Psychologists who study development are interested in behavioral changes that typically accompany increased chronological age. One way to measure these changes is through a cross-sectional study. This type of research design tests people of different ages at the same point in time, as shown here.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

2. If we find differences among the age groups in a cross-sectional study, this might indicate true developmental changes. But these groups were born at different times in history, into different generations, or cohorts. The cohorts have had different life experiences. Therefore, any differences between these age groups (such as in their use of social media) could be due not to age, but instead to generational differences in life experiences—the cohort effect.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

The image includes three groups of the same people at different ages in their life. The first group is when they are 20 years old, the second group is when they are 30 years old, and the last group is when they are 40 years old.

3. To control for the cohort effect, researchers sometimes measure developmental changes with a longitudinal study. This type of research design tests the same individuals (or the same cohort) at several different points in time, as shown here.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

4. By eliminating the cohort effect (because all the individuals are from the same cohort), we have more confidence that any differences from one time of testing to the next are actually due to development.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

5. Let’s apply these two research designs to the study of memory. Suppose that we use a cross-sectional study to test groups of people of ages 30, 50, and 70 on their memory for the names of famous psychologists. The memory test will be a recall test, because we will ask the participants to write down as many psychologists as they can remember. Try to predict the results of this study.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

The image is a horizontal bar graph, with the bars running from left to right. The X axis is labeled “Memory performance in percent correct” and ranges from 0 to 80 in increments of 20. The Y axis has three groups labeled: Age 30, Age 50, and Age 70. The Age 30 group had a memory performance score of 70% correct. The Age 50 group got 55% correct. The Age 70 group got 30% correct.

6. The most likely result in this cross-sectional study is that younger adults would outperform older adults on the recall test, as shown on the graph. Is this proof that memory declines sharply with age? Not necessarily. Remember the cohort effect. Because the younger age groups are more likely to have taken a psychology course, they likely had greater exposure to the names of famous psychologists. If we had asked all three groups to recall the names of famous generals from World War II, the older adults would probably have outperformed the younger groups!

Review

concept_review

Review

Select the NEXT button to continue with the Review.

The image is a horizontal bar graph, with the bars running from left to right. The X axis is labeled “Memory performance in percent correct” and ranges from 0 to 100 in increments of 20. The Y axis has three groups labeled: Age 30, Age 50, and Age 70. For each age group there are two bars, one representing the recall test and one representing the recognition test. The approximate data for this graph is presented in the following table: Table header: Memory performance (percent correct). Column 1 header: Age Column. 2 header: Recall. Column 3 header: Recognition. Raw 1 - Age - 30 - 70 - 85. Raw 2 - Age - 50 - 55 - 80. Raw 3 - Age - 70 - 30 - 70. The data shows that as age increased, scores in recall and recognition decreased. However, the decrease was less for recognition, which remained more stable, than for recall.

7. In addition, the older adults were probably at a disadvantage because we used a recall test (which asks people to retrieve information from memory, with minimal prompts). If we were to use a recognition test (which presents information and asks people to indicate whether it matches their memory), all age groups would likely perform better, but the older group would probably gain the most, as shown on this graph.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

The image includes three groups of the same people at different ages in their life. The first group is when they are 30 years old, the second group is when they are 50 years old, and the last group is when they are 70 years old.

8. Finally, a better way to measure age changes in memory would be to test the same cohort across time, using a longitudinal study. This would eliminate generational differences in exposure to the information that would need to be recalled or recognized. If we found differences in memory performance, we would have more confidence that the differences were related to age (developmental change) rather than to cohort.

Practice 1: Comparing Cross-Sectional and Longitudinal Studies

true
practice_1

Practice 1: Comparing Cross-Sectional and Longitudinal Studies

Select each button to learn about that type of developmental research design.

The two standard research designs used in studying development are called cross-sectional studies and longitudinal studies.

asset/activities/dev_research_designs/images/n37un10.svg

In a cross-sectional study, individuals in two or more different age groups are tested at the same historical time. Therefore, any one column in this table would represent a cross-sectional study.

In a longitudinal study, the same group of people (or people from the same cohort) are tested at two or more different times. Therefore, any one row in this table would represent a longitudinal study

Practice 2: Recall vs. Recognition Memory

practice2
true

Practice 2: Recall vs. Recognition Memory

Select one of the maps to test your memory for the names of countries in that geographic region.

One consistent finding from cross-sectional studies of memory is that compared to young adults, older adults perform more poorly on memory tests. Interestingly, this performance gap is much larger on recall tests than on recognition tests. Let’s demonstrate the difference between these two types of tests by having you first recall, then recognize, the names of countries in Europe or in Africa.

The continent of Europe consists of more than 40 countries. In the spaces below, list any 15 of those countries, and then select the SUBMIT button. Unfortunately, you will need to spell the name of the country correctly in order to get credit for recalling that country. Your performance on this demonstration test will not affect the course points you earn for this activity.

Here is a list of 20 country names. For each name, select YES or NO to indicate whether it is the name of a country in Europe. When you have responded to all the names, select the SUBMIT button.

The continent of Africa consists of more than 50 countries. In the spaces below, list any 15 of those countries, and then select the SUBMIT button. Unfortunately, you will need to spell the name of the country correctly in order to get credit for recalling that country. Your performance on this demonstration test will not affect the course points you earn for this activity.

Here is a list of 20 country names. For each name, select the YES or NO button to indicate whether it is the name of a country in Africa. When you have responded to all the names, select the SUBMIT button.

Quiz 1

matching_test

Quiz 1

Match the terms with their descriptions by dragging each colored circle to the appropriate gray circle. When all the circles have been placed, select the CHECK ANSWER button.

Select the NEXT button and move to Quiz 2.
Perhaps you should go back to review the information about developmental research designs and types of memory tests.
longitudinal study
cross-sectional study
recognition test
development
cohort effect
recall test
a type of research design in which people of different ages are tested at the same historical time
changes in a person’s thinking and behavior that typically accompany increased chronological age
a type of research design in which the same individuals (or people from the same cohort) are tested at several different historical times
a method of measuring memory by asking participants to retrieve information that they had stored earlier
a method of measuring memory by showing participants the information and asking them to indicate whether it matches what they had stored earlier
differences between age groups that are the result of generational differences in life experiences, not developmental changes

Quiz 2

multi_mc_test

Quiz 2

For each statement, select one of the buttons to Indicate whether the statement is True or False. When responses have been selected for all of the statements, select the CHECK ANSWER button.

Select the NEXT button and move to the Conclusion.
Perhaps you should go back to review the information about developmental research designs and types of memory tests.
True
False
Comparing the memory performance of 20-year-olds and 70-year-olds on a test involving recent scientific discoveries would be unfair because of the cohort effect.
True
False
Researchers believe that cross-sectional studies are the best way to measure true developmental changes.
True
False
The gap between the memory performance of young adults and older adults is larger on recall tests than on recognition tests.

Conclusion

end_slide
Rawpixel Ltd/Getty Images
Congratulations!
You have completed the activity Title