Children's understanding of gratitude, generosity, and reciprocity

Grateful people are relatively more healthy, happy, and socially supported than others (Wood et al., 2010), and studies show that feelings of gratitude are associated with generosity, reci- procity, and prosociality (McCullough et al., 2001; Tsang, 2006; 2007). Saying "thank you" is rational and adaptive, so why is it often difficult to train young children to say, "thank you?" Three experiments explore children's intuitions about the meaning of "thank you" in the context of gift-giving. Experiments 1 and 2 reveal that both children ages 3-5 and adults view expressions of gratitude as cues to future reciprocity. However, Experiment 3 reveals that 7- to 8-year-olds and adults, but not 3- to 5-year-olds, also interpret gratitude as a cue to future generosity. Because preschoolers link reciprocity, but not generosity, to expressions of gratitude, it may be rational for young children to avoid saying "thank you."