Toddlers who watch educational DVDs do not improve their vocabularies. Researchers at the University of California, Riverside, studied 96 children between 12 and 24 months who were tested on measures of vocabulary and general development. Half of the children were then given an educational DVD to watch in their homes. After six weeks there was no evidence children learned the words specifically highlighted in the DVDs and watching the DVDs was unrelated to measures of general language learning. The children whose parents reported that they begun watching infant DVDs at an early age actually scored lower on a test of vocabulary knowledge. The researchers thought this might be either because parent bought the DVDs for children who were already falling behind or that the parents who bought the DVDs spent less time talking to their children or that the DVDs themselves had a negative effect on children's learning.