Building machines that better understand human goals

In a classic experiment on human social intelligence by psychologists Felix Warneken and Michael Tomasello, an 18-month old toddler watches a man carry a stack of books towards an unopened cabinet. When the man reaches the cabinet, he clumsily bangs the books against the door of the cabinet several times, then makes a puzzled noise. Something remarkable happens next: the toddler offers to help. Having inferred the man's goal, the toddler walks up to the cabinet and opens its doors, allowing the man to place his books inside. But how is the toddler, with such limited life experience, able to make this inference?