Duden 91:
"Hexis is the Greek word for attitude, for the habitual state in which a person finds herself. Hapsis is a technical term used by psychologists to refer to perception through the sense of touch. In the 1960s, some tried to coin an equivalent English word, sensitivity, to describe such perceptions."
Thus, "haptic hexis" would be "a way of being, feeling, and sitting within oneself that is oriented not primarily by visual reference but by touch, taste, the sense of space, the feel for atmosphere"
opsis is Greek for vision-- an "optic hexis," in contrast to the haptic hexis, is "when the 'state' of a person is oriented primarily by visual representation, imagination, or graphics"
thanks to "new optical devices," we currently live in an era where the optic hexis reigns supreme (Duden notes that "[t]he formation of the fetus is to a large extent the history of its visualization")
and we lack an adequate "history of hapsis," which is in part Duden's project