Haptic visuality and optical visuality are not completely opposed, but exist on opposite ends of the same spectrum. For Marks, as for Deleuze and Guattari these forms slide into each other, occupying a range of relations depending on the media object. Marks further describes haptic images (those which invite a haptic look) are often grainy, distorted and highlight our inability to see. Because we cannot identify an Other space and Other figures, our haptic look rests on the surface of the image rather than penetrating into it. We sense it with our bodies, treating this other surface as another skin. Optical images, on the other hand, portray a figures for a viewer to identify with, a space to exist in. Few media works are ever completely haptic, but rather depend on the oscillation between haptic and optical visuality. This oscillation is one between visual mastery and loss of reference and control; for Marks this is what makes haptic media erotic.
http://transliteracies.english.ucsb.edu/post/research-project/research-clearinghouse-individual/research-reports/haptic-visuality-2