“The message is essentially to read the right books at the right time. So when you are reading to infants when they are younger, and you name characters in a book with a proper level name like Betty, they tend to pay more attention to those characters, and they learn more about those characters. It seems they are a little bit more engaged when the characters have names.”
— Lisa Scott, psychology professor at the University of Florida, “Read The Right Books At The Right Time: A Learning Sciences Exchange Fellows’ Project,” New America, August 26, 2020
Eye on Early Education is a blog of Strategies for Children, an organization that works to ensure that Massachusetts invests the resources needed for all children, from birth to age five, to access high-quality early education programs that prepare them for success in school and life. The blogger, 
eyeonearlyeducation.org 
I’d like to see the science behind this claim. My understanding is that 9 month olds are listening for the parts of patterns of the language spoken by the important people around them.And they are looking to see what these sounds look like on the lips of the reader/speaker. Would like to see the evidence that naming a story book character makes a difference.
Here is an article by Lisa Scott that provides more information on her research.
https://theconversation.com/for-babys-brain-to-benefit-read-the-right-books-at-the-right-time-83076