Infants were shown a cover with a protuberance, suggesting a hidden object under the cover.
Infants aged 9.5 months showed surprise when the cover was removed and there was nothing under it, but didn't show surprise when the object revealed was much smaller than the protuberance suggested.
Demonstrates that infants initially have a very basic understanding of the physical world.
12.5 month-old children showed surprise when there was a mismatch in the protuberance and the object.
Shows that this understanding becomes more refined and sophisticated with age.
