houdini is a normally developing one-year-old watching a magic act. the magician he is observing has just rolled a ball into what looks like a solid wall. however, when the ball reached the wall, the ball appeared to roll through it. according to research findings by baillargeon, one would expect that houdini's most likely reaction would involve

I believe the answer is: surprise, and the infant will stare at the spot the ball appeared to go through the wall.

In the field of psychology, this occurence is referred to as object permanence, whcih is the knowledge that an object would not dissapear even if we stop paying attention to it. At one year old, the concept of object permanence is still not fully developed yet.