She along with her colleague Naja Ferjan Ramirez has conducted the largest study of infants (ages 7–33.5 months) designed to assess efficiency of a science based approach to teaching a foreign language to infants.
Here is a short summary of their study: Igniting Bilingual Learning. The full results are published in "Mind, Brain, and Education" (a peer-reviewed academic journal): "Bilingual Baby: Foreign Language Intervention in Madrid’s Infant Education Centers"
For those who don't have time to read the article, let me quote the conclusion:
The current study demonstrates that 18 weeks of foreign language exposure in daily, social, 1-hour long play sessions with native-speaking tutors using a research-based method leads to highly significant gains in foreign language comprehension and production in children between 7 and 33.5 months of age.