The author herself replied to the comments on that page. It is the same person that has published several books on child psychology: https://www.amazon.com/Eka

The author herself replied to the comments on that page. It is the same person that has published several books on child psychology: https://www.amazon.com/Ekaterina-Murashova/e/B00MWS9SN8 https://www.amazon.com/Ekaterina-Murashova/e/B00MWS9SN8 http://www.samokatbook.ru/files/Samokat_catalogue2008.pdf http://www.samokatbook.ru/files/Samokat_catalogue2008.pdf Edit: Seems like you are questioning if the author actually carried out the experiment that she claimed. In that case there is indeed no proof or cross-reference available.