The motor is probably under there and it's a nice warm spot. Also there's something about cats and stairs. Mine used to love to scurry around my feet at the top of the stairs. I used to joke that they were plotting to kill me.
I'd feed it that fuckin' yappy dog.
This black and white image can appear as if it's in color.
http://www.iflscience.com/brain/image-can-trick-your-brain-and-make-you-see-it-color/
