"The old aphorism is wrong. A picture isn't worth a thousand words!
According to neurological research, the brain is able to process print on a page at a rate of approximately one hundred bits per second. But the brain can process a picture at approximately one billion bits per second. Mathematically speaking, a picture is literally worth ten million words!
Images are important because of the way the brain processes information. The brain recognizes and remembers shapes first, colors second and content third. It is the sequence of cognition. If you want people to listen to the content of what you have to say, you better think about how you shape it and color it. And if choosing color schemes seems to be void of spiritual significance read the book of Exodus. A dozen chapters are devoted to design. God gives very specific instructions about colors and scents to be used in the Tabernacle."
His article is on how to "brand" a sermon, but this point on imagery caught my attention. Read the whole article on his blog here.