To cope with the rising volume of information in humancomputer interfaces, explicit and attentive interaction is more and more frequently replaced by implicit means of information exchange, supported by context-and activity-aware systems and applications. The trend of excessive information is, however, still ongoing, calling for further solutions to reduce a persons cognitive load or level of attention. Subliminal interaction techniques are considered a promising approach to deliver information to a person without causing much supplementary workload. This workshop aims at discussing the potential of subliminal perception to improve the information flow for human-computer interaction in the light of the fact that, up to now, the results have been mixed. One group of researchers has provided evidence that subliminal stimulation works, but the other has found that it does not, or even cannot, work. To clarify this issue, experts from various domains attending the workshop will discuss how subliminal effects can be scientifically supported or how a certain claim could be empirically refuted.

In this study, we present a method for psychophysical measurements of surface roughness sensitivity by indirect touch, using a 3D hapto-visual virtual reality (VR) device. In a texture-difference-recognition test subjects glided a pen-like stylus on a virtual surface. The surface was divided into five areas: one central, and four surrounding areas. The roughness of the central area was kept constant throughout the experiment. In each run, three of the four surrounding areas were kept at the same roughness as the central surface, and one, randomly, was different. From run to run, surface roughness was changed following a binary search paradigm. If a subject recognized the portion of the surface with a different roughness, then the roughness was reduced by half; if not, the roughness increased, and so on, until the desired number of steps was achieved. This approach allows us to take advantage of the programmable capabilities of a VR, so that the limit of aware recognition between surfaces with different roughness can be measured with more precision than in conventional methods. To illustrate this paradigm, results from a preliminary study are presented.

This paper explores the role of haptics in immersive telecommunication applications and analyzes the contribution of haptics to the sense of presence in a variety of applications. Based on the concept of embodied presence, a new construct, resonance between the human cognitive-body system and the streaming sensory information from the environment, is suggested to be a principal factor in "presence." Resonance is defined as the level of mutual synergy between sensory information and action, relative to the physical environment. It occurs when the sensory flow supports action. Since the human haptic system is unique in that it both perceives sensations from the environment and acts on the environment, it has a central role in resonance and in presence. Haptics in the natural world supports efficient bodily action and, in a tacit way, supports development of higher reasoning skills. This requires resonance and embodied presence. The current visual-haptic gap between levels of technological development creates a bottleneck in developing fully tele-immersive applications.