By conducting research for my essay and for my final project not all interactive art has been approached by using technology or digital interface's. For example the work of Youri Messen-jaschin with his installation piece named "Vertigo I" 2002. This piece pictured bellow plays on the users interaction with the room and the vertical lines that he had placed in and around the room.
image taken from http://www.absolutearts.com/cgi-bin/portfolio/art/your-art.cgi?login=messenjaschin&title=Vertigo_I-1018709509t.gif
this installation relies on the users interaction with the space that the piece is situated in. depending on where you view the piece from in the room the result of the piece or the feedback the piece gives is different.
Another example of a type of interactive art that does not rely on technology to be considered interactive is the kinetic sculptures like mobiles for example. ("A mobile is a type of kinetic sculpture constructed to take advantage of the principle of equilibrium. It consists of a number of rods, from which weighted objects or further rods hang. The objects hanging from the rods balance each other, so that the rods remain more or less horizontal. Each rod hangs from only one string, which gives it freedom to rotate about the string.") quote taken from http://en.wikipedia.org/wiki/Mobile_(sculpture).
an example of these kinetic sculptures would be the work done by Alexander Calder. his piece entitled "Red mobile"(1956). the piece show below can be considered interactive art as it reacts and interacts to the environment that it is placed within by responding to the air flow of the environment.
image taken from http://en.wikipedia.org/wiki/File:Calder-redmobile.jpg.