From experience, I am skeptical of this hypothesis. Little kids will absolutely recall memories from before they knew how to speak.
Just last week, my two-year-old spied the freezer pops in storage. She pointed out back and said, "Eat on deck!" Clearly, she remembered eating freezer pops on the deck, but the last time she did that was last summer (northern hemisphere) when she didn't know how to talk at all, let alone say "deck".
Just last week, my two-year-old spied the freezer pops in storage. She pointed out back and said, "Eat on deck!" Clearly, she remembered eating freezer pops on the deck, but the last time she did that was last summer (northern hemisphere) when she didn't know how to talk at all, let alone say "deck".