Marilyn Rose McGee
Presenting Haptic Information
Despite the increasing prevalence of haptics in today's computing environments, the effective representation of haptic information is still a relatively new design problem for human computer interaction research. Force feedback interfaces in particular pose a variety of interface design questions. What can and cannot be displayed convincingly through such devices for example? If such devices are limited in the information they can convey can other modes of interaction be exploited overcome these limitations?
The perception of surface texture for example is a major issue in haptic environments. The texture of a virtual surface can both increase the sense of realism of an object as well as convey informational content regarding what the object is, where it is, what it is for, and so on. It is not entirely clear which class of device (tactile or force feedback) is most suitable for such texture representation. This is partly due to the complex nature of real texture perception and the uncertainty of the exact physical parameters that underlie the perception of textures. Force-feedback devices convey texture by actuating forces on the users' finger, hand, or body. These devices are becoming realistic interaction tools in a variety of applications where texture perception may be of importance. It is crucial therefore that designers know the range of textural information available through the haptic modality in virtual environments.
Surface roughness is the primary perceptual cue that permits observers to discriminate among textured surfaces. The primary physical determinants of perceived roughness however are not clear and so are proving difficult to simulate in virtual environments. Our preliminary work has shown that the frequency of a sinusoidal-wave-based texture has an affect on perceived roughness. The results from a paired comparison study of 6 such textures began to suggest a bimodal distribution in fact, confirming the complex nature of the concept of roughness.
The current study involves a set of 8 textures (varying in frequency) of this sinusoidal nature. Each stimulus is compared to each of the others in the set. The user is asked to explore a series of pairs of these textured patches and make a forced choice decision relating to the pair. The user can rate the texture on the left as roughest, the texture on the right as roughest, the textures as the same roughness, or the textures as not comparable on the same roughness scale. In this way, the proportion of times each texture is rated as rougher than each of the other textures can be determined.
Hypothesis 1 - the frequency of the texture will have an effect on the proportion of times that texture is rated as rougher than each of the others.
Hypothesis 2 - the frequency of the texture plotted against an overall perceived roughness score will yield a bimodal distribution (illustrating the fact that there is no simple monotonic mapping from frequency of texture to its perceived roughness).
For recent publications on this work please see my publications page.