Research Method Labs

Research Method Labs 

42. Specialized Designs Exercise: Developmental

Following are the reference and an adapted abstract of a published research paper.

• Identify the kind of specialized developmental design that was used in the study.
• Identify the variables (e.g., dependent, independent, quasi-independent, and control) that were studied.
• What are the advantages of using this specialized design?
• How could you redesign the study using a different specialized developmental design? What would be the advantages and disadvantages of using this alternative design?

Plomin, R., Fulker, D. W., Corley, R., & DeFries, J. C. (1997). Nature, nurture, and cognitive development from 1 to 16 years: A parent-offspring adoption study. Psychological Science, 8, 442–447.
Adapted Abstract
Studied 245 adopted children and their biological and adoptive parents as well as 245 matched non-adoptive parents and offspring to examine genetic versus environmental influences on cognitive development over a 20-year span. The children were tested at 1, 2, 3, 4, 7, 12, and 16 years of age using standard intelligence tests. Results show that the adopted children resembled their adoptive parents slightly in early childhood but not at all in middle childhood or adolescence. In contrast, during childhood and adolescence, adopted children become more like their biological parents and to the same degree as children and parents in control families. Although these results were strongest for general cognitive ability and verbal ability, similar results were found for other specific cognitive abilities such as spatial ability, speed of processing, and recognition memory. These findings indicate that, within this population, genes that affect cognitive abilities in adulthood do not all come into play until adolescence and that environmental factors that contribute to cognitive development are not correlated with parents’ cognitive ability.

43. Learning Check: Bias and Control and Specialized Designs

1. I want to design a study to determine the effects of age on quantity of social interaction. I will measure how many friends each of my participants reports they speak to on a given day. I will use three groups of participants: 8- to 10-year-olds, 12- to 15-year-olds, and 17- to 18-year-olds. Thirty participants will be in each group. I am using a cohort-sequential design.
   1. Describe how I might change this study to use a longitudinal design.
   2. Can I determine if age causes a change in quantity of social interactions with this study? Why or why not?
   3. List one possible covariate that I might use in this study to remove some of the variability in the data.
2. I want to conduct a study to determine at what age (if any) an instructional technique given to second-, fifth-, and ninth-grade classes improves learning. The instructional technique will be used for 6 months in each class. Describe how I would design this study as a cross-sectional design. What type of design should I use if I want to measure learning? What will my dependent variable be in this design?
3. You want to conduct an experiment to determine the effect of running on verbal ability. You ask participants to run 1 mile and then state all the words they can in a 30-second period. List two confounding variables that you should consider controlling for in this experiment and how you might control for them in the design.
4. For each of the following design types listed, state one advantage and one disadvantage of using that design:
   1. within-subjects design
   2. longitudinal design
   3. small-n design
5. Describe how you would conduct an interrupted time series design to determine if the public’s trust of politicians changed after September 11, 2001.
6. How do discrete trials and baseline small-n designs differ?
7. Suppose you are a school psychologist working in an elementary school. A teacher has come to ask for your help with a student who has been disruptive to her class by consistently getting out of her seat, talking without raising her hand, and refusing to work on activities with a group. You propose a reward system for the student such that she receives a sticker each time she exhibits appropriate classroom behavior (e.g., staying in her seat for a segment of the class, talking after raising her hand, working cooperatively with a group in an activity). She can then redeem a set number of stickers for small prizes from her parents (e.g., small stuffed animals). Describe how you might implement this reward system for the student in an A-B-A design to determine if it is effective in increasing appropriate classroom behaviors for her.