In another piece of research, infants were shown a cover with a protuberance suggesting an object hidden under the cover.
Infants aged 9.5 monthsshowed 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.
This shows that the 9.5 month old infants had some understanding of the physical world, but the understanding was limited.
However, 12.5 month old infants showed surprise when there was a mismatch in the protuberance and the object. This shows that our understanding of the physical world becomes more sophisticated and developed with age and experiences.