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.
IBM Smarter Cities campaign. Ogilvy Mather, France. Kaan said "This one is an IBM smart cities campaign product/ad. It is great because it is intelligently complementing the ad with the functionality of the design, so perfectly that the audience really gets the idea of the “Smarter Cities” out of this design."