Simplify the following text for a Grade 14 native English-speaking person.
Original: It is less widely known that Pavlov 's experiments on the conditional reflex extended to children , some of whom apparently underwent surgical procedures , similar to those performed on the dogs , for the collection of saliva .
Simplified: It is less widely known that Pavlov 's experiments on the conditional reflex included children , some of whom apparently underwent surgical procedures , similar to the dogs , for the collection of saliva .