Construir la memoria colectiva desde un caso particular de feminicidio

Remote tactile feedback on touch surfaces is a form of tactile sensory relocation and thus a form of sensory substitution. However, the amount of necessary learning and adaption is greatly reduced, as the substitution is intrasensory, i.e. no translation of sensory information into another

4.3 Towards Remote Tactile Feedback 81 Movement of finger(s) Body GUI Sensors (position) Coupling Device Actuators (tactile) x(t) y(t) RTF device touch surface

Figure 4.8: Structure of an interactive surface incorporating remote tactile feedback.

modality is necessary. Underlying concepts of sensory substitution also apply to remote tactile feedback systems:

• neurological mechanisms (e.g. brain plasticity, exteriorisation)

• psychological principles (e.g. tactile-sensomotory feedback loop)

Therefore, an interactive surface with remote tactile feedback can be structurally described as a sensory substitution system (see figure 4.8): Information on the position of the finger in relation to the GUI depicted on the touch surface is captured by the touch surface’s sensors. The information is transduced to a set of signals x(t) and encoded into a set of messages for the tactile actuators which are part of the device. Then, the information is presented to the body of the user. The feedback loop is closed when the user moves his finger on the surface and thus alters the resulting tactile stimuli. When designing touch systems incorporating this principle of feedback, the basics of sensory substitution have to be taken into account.

In summary, the notion of sensory substitution helps to augment the capacities of humans by enriching available sensory channels and by creating novel forms of stimuli. Furthermore, remote tactile feedback can be seen as a form of sensory supplementation, facilitating novel forms of perceptions and bringing new ways of coupling with our environment [Lenay et al., 2003]. This concept is a fundamental part of my research.

Chapter

5

Remote Tactile Feedback on

Interactive Surfaces

In the previous chapters, I identified challenges of direct touch human-computer interaction which have been addressed by the integration of programmed tactile stimuli. Various techni- cal concepts to create and utilize cutaneous feedback on touch surfaces exist. Evaluations of tactile touchscreens have shown improved usability and user performance. In this and the next chapter, the concept of remote tactile feedback is presented as a valid alternative solution for tactile augmentation of touch surfaces with additional beneficial characteristics.

5.1

Definition and Problem Space

The term ’remote tactile feedback’ describes the spatial dislocation of cutaneous stimuli which are synchronized with an interaction with direct touch surfaces onto parts of the user’s skin which are not in contact with the screen. Tactile transducers form an output mechanism whose sig- nals are synchronized with the user’s input on the interactive surface, thus creating a tactile- sensomotory feedback loop. Based on this synchronism of stimuli, users integrate the remote tactile cues, visual feedback and auditory stimuli coming from the screen into an overall multi- modal sensation. Figure 5.1 depicts four principles of providing the users of interactive surfaces with remote tactile stimuli. In order to maintain continuous contact of the actuators with the user, actuators could be part of wearable interfaces, can be integrated into the user’s clothing or embedded into the user’s direct environment (e.g. the frame of the interactive surface or the seat of the user).

In our everyday world, we actively palpate and manipulate unknown objects with our hands. In combination with other sensory cues, we thereby form a coherent internal representation of the physical object and its characteristics in our brain. This concept has been transferred to the

84 5 Remote Tactile Feedback on Interactive Surfaces

a

_b

c

d

Figure 5.1: Alternative methods of integrating tactile actuators into the user’s direct envi- ronment. a: wearable interfaces, b: actuators embedded into the touch display’s frame, c: actuated clothing, d: actuators embedded into the user’s seat.

interaction with non-physical or digital information: The concept of direct manipulation also re- lies on the "continuous representation of the object of interest" [Shneiderman, 1984] and actions which resemble those from the physical world. The "coincidence of input and output space" [Ishii, 2008] and "realtime response" [Ishii, 2008] also are a fundamental requirement for the concept of TUIs. Here, tangible and intangible representations are ’perceptually coupled’ to achieve a ’seamless interface’ [Ishii, 2008].

The concept of remote tactile feedback clearly follows this argumentation. Input and output space are perceptually coupled, the communication of sensory cues and responses happens in realtime. The non-physical object of interest is continuously present and the input mechanisms resemble those from the ’real world’. However, the output space is extended onto the whole body surface of the interacting person. This spatial expansion also conceptually expands the concept of touch interactions and entails more versatile and creative possibilities.

The notion of remote tactile feedback accommodates ongoing technical and social developments. Taken into account are the growing pervasiveness of touch surfaces, the evolution of interactive surfaces towards non-planar, non-solid and flexible forms (see section 2) and the necessity for ad- ditional tactile feedback (whose beneficial effects on user performance have been shown before, see section 3.3.2).