Metacognitive Apes

I've been fascinated by tip-of-the-tongue moments. It's estimated that, on average, people have a tip-of-the-tongue moment at least once a week. Perhaps it occurs when you run into an old acquaintance whose name you can't remember, although you know that it begins with the letter "J." Or perhaps you struggle to recall the title of a recent movie, even though you can describe the plot in perfect detail.

What's interesting about this mental hiccup is that, even though the mind can't...