Bob,
My son's exposure was first from the videotapes, then from books made from the television series. (The series that predated Shining Time Station, and came from Brit Arcroft.)
We now have a massive wooden railway in home, complete with some the Thomas wooden railway trains. (The track is mostly Brio, along with some rolling stock.) He also has several of the die cast engines as well.
He learned his numbers and colors from Thomas. He could tell a steam engine from a diesel when he was four or five. To him, every steam locomotive looks like one of the Thomas engines, and our Mamod live steam roller is named "George" after the steam roller in some of the Thomas episodes.
Thomas was a major factor in turning him on to trains, and has given us a mutual hobby to enjoy together. He has accompanied me on most of my "steam hunting" trips since he was a baby, along with the rest of the family.
-James Hefner
Hebrews 10:20a