ETS, whose prestige enhanced the credibility of its findings,[50] conducted two landmark summative evaluations in 1970 and 1971, demonstrating that Sesame Street had a significant educational impact on its viewers.[2][51] These studies illustrated the early educational effects of Sesame Street, and have been cited in other studies of the effects of television on young children.[49][note 7] ETS reported that the children who watched the show most learned the most,[52] and achieved better results in letter-recognition skills. Three-year-olds who watched regularly scored higher than five-year-olds who did not; children from low-income households who were regular viewers scored higher than children from higher-income households who watched the show less frequently. Similar results occurred in children from non-English-speaking homes.