Every emotion term was listed in a vocabulary checklist. Groups of volunteers from the general population (see “Participants” above) were asked if they knew the meaning of each word. The volunteers ranged from age 4 to 16 years old and were stratified by age. For individuals aged 12–16, self-report was accepted. For individuals age 4–11 years old, parent- or teacher-report was collected. This questionnaire survey method invited the participant to choose one of three response options for each word: Clearly Understood, Not Understood, and Possibly Understood. This method (parent- or teacher-report) was used in the development of the Communication Development Inventory (Fenson et al., 1994 (link)) and has been found to be reliably correlated with comprehension tested in the lab. Only those items endorsed as Clearly Understood were judged to be within the comprehension of an individual. Finally, words where data was not available from all six age groups were not included in the results, since this was a developmental study1.