But when we’re limited to just one side of a two-sided dialogue—or “halfalogue”—our brains have to work harder to guess what’s coming next.

One possible reason: Since you're hearing not a dialogue but a "halfalogue, " you're doomed to fail when you try to predict when it will end or figure out what's going on.

Psychologists had volunteers perform tasks that required concentration. And while the subjects worked, they were treated to either a dialogue or halfalogue the scientists had previously recorded.