What’s Wrong with This Picture?

Many parents think their babies are geniuses. Now a report in Nature argues — not altogether convincingly — that tots can actually add and subtract at five months. After showing objects to infants, a psychologist hid the objects with a screen; she then reached behind the screen to add or remove one. But she added or subtracted objects surreptitiously as well. When the screen was lifted, the infants stared longer at a wrong number of objects than they did when the result was correct. Conclusion: they were doing a double take. Ah, science!