No Comments Written by Robert on May 26, 2008 – 1:54 am

Haptics, the science of the sense of touch, comes from the Greek, haptikós, to grasp. There is a difference between the stricter definition of haptics, that is, tactile perception (from the Latin, tangere, to touch), which refers to the touching of surfaces, and the broader definition of haptics that includes kinesthesia (from the Greek, kinesis, movement and aesthesis, perception), or the sensing of movement in the body.

To date, design has largely used the stricter definition of the term.

The sense of touch is understood as a specific and autonomous sense related to external perception.

Haptics, the science of touch, is therefore concerned with the transmission of such sensations as pressure, vibration, pain, and temperature. Design is concerned with how significant touch is when operating and controlling technical machinery and equipment. For this purpose, different forms of levers, switches, knobs, and buttons are tested for their operational reliability. What is important is the distinct feedback the user experiences through touch or other senses.

This allows the user to determine, by the amount of haptic resistance on a push-button switch for instance, whether pressing it has activated the electric system or not. This is also conveyed acoustically by a clicking sound and visually by a small light next to the button. The light by the button is important, because while the button usually returns to its original position after being pushed, the light remains on as long as the electric system continues to be activated.

The surplus feedback involving three senses makes it highly unlikely that the machine will be operated incorrectly. The same applies for flip switches and levers. Because these, unlike a push button switch, allow the user to see immediately if the switch has turned a system on or off, in this case, one can forgo the small light even if the redundant three-way feedback system is retained.

These examples show how important haptic feedback is, because blind or deaf users can safely operate mechanical equipment equipped with these switches. This is only partly feasible with a push-button switch. Another advantage of this now rather old-fashioned switch control system is the protruding position of a control panel switch. Users who are blind or working in the dark can examine the control panel and its switches by touch and, once briefed, can also operate it.

An example of an inadequate form of tactile control is the touch screen. It may well allow the user to control it by touch, but it lacks any haptic feedback, making the user totally dependent on visual and acoustic feedback. Blind users cannot identify different activation fields, because they only feel smooth, cold glass, and they do not receive any haptic feedback that confirms that the field has been activated. Today’s demand for designs suited for the disabled could actually trigger a revival in the design of control panel switches and buttons (Screen Design, Universal Design).

Another example of the relevance of haptic feedback can be found in the automobile industry. Drivers lose their sense of speed in quiet luxury cars. For safety reasons, this has led to the idea of actually creating a deliberate vibration, activated when the car reaches a certain speed, so that the haptic sense can assist the driver to recognize the speed at which he or she is driving (Safety Design).

The most comprehensive definition of haptics was developed by Edmund Husserl (1859–1938), in the context of the philosophy of physical phenomenology, giving weight to individual subjective experience as the source of our understanding of objective phenomena.

This includes a general theory of people’s kinesthesia. The body and its haptic sense play a central role in this philosophy of perception. Husserl defines the body in relation to the constitution of an object and space as:

1. a medium of all perception

2. a free-moving entity of the sensory organs and

3. a center of orientation.

As a free-moving entity, the body expresses the function of spontaneity, the “I can.” “I” decide whether I want to go left or right in a room, straight ahead, or backward. “I” decide whether I want to run my hand along the surface of a table to feel whether a shiny mark on it is sticky or not.

“I” tilt and turn my head to be able to better hear if the cat is meowing. In addition to the function of spontaneity, there are also two correlating classes of sensations that belong to the constitution of space and object: first, the sensations that constitute the characteristics of things, for example, color sensations and sensations of surface properties, and second, the kinesthetic sensations, meaning the physical sensations of the different body parts, like the sensation of eye movement when looking or the sensation of the arm moving when reaching out to touch something. In fact, it is impossible to imagine a perception, regardless of which sense is activated, without a corresponding physical sensation.

The body is in almost constant movement; even while you are sitting down, your eyes blink, your head turns, you cross your legs, you even feel your inner organs: your heart beats, your belly rumbles. Of course, people are usually less focused on their kinesthetic bodily sensations and more on the sensation of perceiving the characteristics of a thing.

But adjusting the settings, so to speak, makes it easier to shift the focus to bodily sensations. When hiking through the woods, most people’s senses are focused on the landscape and the plant and animal life there; they become aware of their own body only if they stumble. Marathon runners, however, exert their bodies so much that their own physical sensations necessarily become the point of focus.

Perception always entails activating more than one sense at a time. If I look at a black, polished table surface, my haptic sense anticipates that the surface of the table will have a sensation characteristic of smoothness. Acoustically, I also expect a squeaky sound if I rub my finger along its surface. For the rational understanding of the external world, our consciousness provides a constant organization of the simultaneous stimulation of the individual senses (Deckungssynthesis).

Ultimately, sensory perception is the product of a system of different physical senses that is constantly balancing the information it assimilates and processes.

Conscious acoustic, visual, haptic, or olfactory experiences form an interactive system of anticipations that are either fulfilled or disappointed in the process of perception. The fact that several senses exist allows even the abstract, isolated “I” to develop an initial form of objectivity, as Husserl shows in Ideen II.

This initial partial objectivity develops when the “I” recognizes haptically when one of the senses is inaccurate or contradictory (for instance, if you have a wart on a fingertip), because the other senses, and the Deckungssynthesis they provide, help the unity and coherence of the perception process to remain intact. This admittedly is not genuine objectivity. Objectivity is only generated from intersubjective association.

Maurice Merleau-Ponty was the first to further develop Husserl’s phenomenology of the body into an intersensory theory, when he more precisely analyzed sensorial interaction. Whereas in architectural theory the broad definition of haptics has long been established and successfully applied in research and doctrine, its experiential, trial and error quality has only recently been recognized in design research.