Baby flashcards have grown in popularity. They are advertised with seemingly amazing effects, like 1½ year old reading and counting.
On the other hand academics seem to either say that they don't have long term positive effect, or worse yet, that they have negative effect (child did not learn at that age, what it should have normally have learnt, for example socializing). See Pat Wolfe's Q&A or book by Kathy Hirsh-Pasek "Einstein Never Used Flash Cards"
Are there any scientific, evidence-based, studies showing that they have either positive or negative effect on children?
Related question: Is “Your Baby Can Read” effective and helpful?