Having had a child of my own in the last few years, I would like to think I understand the phenomenon. When we lack comprehensive language, we do not store memories as narrative experiences as we do as adults, rather just as semantic connections and correlations. There have been more than a few occasions where I have been doing something like changing a diaper, rocking her to sleep, playing with her in the bath, and I have had the intense sensation of “I remember what this felt like” - not necessarily a specific instance, but rather a remembrance of sensation.
My earliest memories are from between one and two years of age, and I know that they are memories as they are things that my parents do not recall, and I have been able to verify, and I know when they are from as we left Hong Kong weeks after my second birthday.
I remember the father of the guy I reconnected with parading around his garden on stilts - my parents denied this ever happened, yet he confirmed his father was indeed into that at the time - and I remember the pigs and chickens under the houses in the squatter’s village near us - again, my parents insisted they had never taken me there - and they had not, but my au pair, who forty years on I reconnected with and asked, had.
There are other bits and bobs, glimpses, that I recall, but can’t say for sure aren’t implants.
I may be getting some of that wrong, too. I was not particularly engaged with that class since I was still a rather immature student, back then. I'm not saying I subscribe to her idea, but it's certainly interesting to think about.
But after reading this comment and the responses to it I'm now realizing the city that she came from did happen to be the one where me and my parents lived for half a year when I was four, so maybe we went to the same kindergarten and were close friends at the time?