Here's an interesting study from across the pond. The United Kingdom's Royal Mail Service wanted to understand the differences between how readers process direct mail messages versus ads viewed on a screen. They asked the firm of Millward-Brown to look into this issue. Working with Bangor University Millward-Brown conducted a rigorous study of the issue using fMRI technology.
Their study found that readers presented with information in card format (physical ad) were much more engaged with the message than readers presented the material in a digital (virtual) format. They found that the physical were more engaging both intellectually and emotionally. This lead them to surmise that the brain would be better able to recall the printed ad over a similar digital one.
Here is a link to a brief synopsis of the study in PDF form:
This study is a good justification for print advertising as well as for direct mail.
Thanks for reading.