I wanted the characters to be most real and relatable to young children. My intuition told me that the more real the images were the more relatable they would be for children. So not matter what type of book I decided to write I wanted to use photographs to help the children learn the best. (I added a brush stroke the images to give it little bit of an illustrated feel for those children who may prefer illustrations.)
Upon doing a little research I have discovered a coupe of studies that have been done on the photography versus illustration question. Turns out my intuition seems to be correct. The studies show that children learn better and have more reading comprehension when the images are more realistic such as photographs. One of the articles I read which sums it up well is by Teri Brown entitled Photographs vs. Illustrations: Which Picture Books Help Baby Learn Best.
Granted the studies focused more on children younger than those my books target (though, I say, no need to wait, start teaching these concepts even when they are babies and they’ll have the vocabulary for it as they grow.) I believe even with as much imagination as children have, they inherently know people do not look like cartoon characters and animals do not talk. Because I believe the message is important, I wanted to make sure their unconscious minds retained the message in the stories instead of possibly disassociating based on unrealistic images.
(Besides I’m a photographer not an illustrator so it made sense to use photography to illustrate my books.)