This element of design is Negative Space. The hand isn't actually holding anything. It implies that there is a light bulb in the empty space. Negative space guides your imagination to finish the image.
This split image and type is design well because of the greyscale coloring. Target audience Design- overall the font selection was perfect because it is still readable. I like the white space on the right gives the illustration depth.
This book cover shows excellent figure ground/negative space. The contours formed by the position of the fox serve as the shape of a boy, I'm assuming "Peter." This empty space also creates a wonderful focal point for the book title to nestle into.