Reading Research Critically

Read the following description of a research study to answer the questions that follow. [Based on an article by Lambert, N. M., Clark, M. S., Durtschi, J., Fincham, F. D., & Graham, S. M. (2010). Benefits of expressing gratitude: Expressing gratitude to a partner changes one's view of the relationship. Psychological Science, 21, 574-580.doi: 10.1177/0956797610364003]

Expressing Gratitude in Relationships

From the time we are children, we are taught to say "thank you," write thank-you notes, and more generally, appreciate what others do for us. Gratitude is an emotional state in which a person is aware of and appreciates that which is valuable and meaningful to oneself. Empirical research suggests that expressions of gratitude are related to relationship satisfaction, and that people like to feel appreciated. While it's clear that the recipient of gratitude benefits from such expressions, Lambert and his colleagues sought to learn whether the person who expresses gratitude also benefits. They hypothesized that when people express gratitude to a relationship partner, they will perceive greater communal strength in that relationship. "Communal strength" refers to a feeling of responsibility for meeting the partner's needs.

In their first study, 137 students (116 women, 21 men) in an undergraduate psychology course completed questionnaires for extra credit. Age of the students ranged from 18 to 37; the median age was 19. Participants completed four measures: Expression of Gratitude in Relationships, Communal Strength, a Social Desirability measure, and Relationship Satisfaction. [Students completed the measures thinking about a romantic partner or a close friend.] The researchers obtained scores on the measures for each participant using accepted procedures. The results indicated that expression of gratitude was correlated with communal strength of the relationship, and that this relationship was maintained even when other variables (e.g., social desirability, relationship satisfaction, participant gender, type of relationship, etc.) were statistically controlled (i.e., these variables did not mediate or moderate the correlation).

In a second study, Lambert et al. sought to determine whether expressions of gratitude predict individuals' subsequent perceptions of communal strength (i.e., at a later time). In this study, 218 undergraduates (171 women, 47 men) first completed the measures at the beginning of a semester (Time 1) and then again 6 weeks later (Time 2). Using correlational procedures, their results indicated that expressions of gratitude at Time 1 predicted perceptions of communal strength at Time 2 (statistically controlling for initial feelings of communal strength, relationship satisfaction, etc.) Lambert et al. concluded that their "findings provide important support for a time-order relationship" between expressions of gratitude and subsequent feelings of communal strength in a relationship. These researchers suggest that expressing gratitude helps the expressers communicate to themselves (in addition to their partner) their desire for the relationship and care for the partner, and that these expressions might result in more relationship-enhancing behaviors.

A. Describe the sampling method used in these two studies. What is the likely population the researchers wish to generalize their findings to and to what extent is their sample representative of that population (i.e., do they potentially have a biased sample)?

B. Identify the survey design in each of these two studies and how Lambert et al. (2010) used these designs to satisfy conditions for causal inference. Which conditions did they meet and which did they not meet in these two studies?

C. Lambert et al. (2010) used four questionnaires in their study to examine the relationship between expressions of gratitude and communal strength in a relationship. The two remaining measures, relationship satisfaction and social desirability, were used to address questions associated with the construct validity of gratitude and communal strength. That is, the researchers sought evidence to demonstrate that expressions of gratitude and communal strength are not the same as relationship satisfaction, nor simply socially desirable responding. Describe the pattern of correlations they likely observed to support the construct validity of their measures.