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Cognitive Science - SAMSS

Bionics & Cognitive Science Abstracts

Symmons, M.A., Richardson, B.L., Wuillemin, D.B.,& VanDoorn, G.H. (2005). Active versus passive touch in three dimensions. Paper accepted for presentation at World Haptics Conference, 18-20 March 2005, Pisa.

Active subjects freely explored virtual three-dimensional geometric shapes using a Phantom force-feedback device. Each active subject’s movements were
used to guide a passive subject over the same stimuli. In Experiment 1 the active subject’s movements were recorded and “played back” to the passive counterpart at a later time – a delayed yoking. Two Phantoms were used in Experiment 2 so that as the active subject explored, the passive subject was guided simultaneously along the same movement pathway. Active exploration yielded significantly shorter latencies than did passive-guided exploration.

Wuillemin, D.B., VanDoorn, G.H., Richardson, B.L.& Symmons, M.A. (2005). Haptic and visual size judgements in virtual and real environments. Paper accepted for presentation at World Haptics Conference, 18-20 March 2005, Pisa.

In three experiments, participants were asked to match the sizes of spheres presented in the haptic and visual modalities. Stimuli were either real or virtual. Real spheres were sets of ball bearings that could be both viewed and touched. Virtual spheres were presented using a Phantom for the haptic presentations or a 3D screen for the visual presentations. Comparing the judgements made within sensory modalities, virtual spheres of a given size were perceived as significantly larger than their real counterparts for vision, but not for haptics. Across modalities, virtual haptic spheres were perceived as significantly larger than their virtual visual counterparts, while there was no significant difference in the judged size of real visual and real haptic spheres. The results have implications for the design of virtual environments where it cannot be assumed that the sizes of objects as depicted by their designers will be perceived in identical fashion across modalities.

Symmons, M.A., Richardson, B.L., Wuillemin, D.B.,& VanDoorn, G.H. (2005). Kinaesthetic and cutaneous contributions to raised-line stimulus interpretation Poster accepted for presentation at World Haptics Conference, 18-20 March 2005, Pisa.

By actively exploring a raised line stimulus with a finger, blindfolded subjects caused another stimulus to move underneath a stationary finger on their other hand in a yoked manner. Subjects were naïve to the fact that the stimulus pairs were rotated versions of each other (e.g., p and d); they were led to believe that the two elements of each pair were identical. The stimulus named by the subject indicated whether they had “attended” to the moving or the stationary hand. Most subjects did not detect that one stimulus was the rotated form of the other. The finger attended to was influenced more by the presence or absence of the raised line (cutaneous information), than whether kinaesthesis was involved, or whether the information acquisition was active or passive.

Richardson, B.L., Symmons, M.A., Wuillemin, D.B.,& VanDoorn, G. H. (2005). Looking through a fingertip. Poster accepted for presentation at World Haptics Conference, 18-20 March 2005, Pisa.

The spatio-temporal pathways followed during active haptic exploration of raised-line letters were recorded and then used to compare haptic (passive-guided) and visual identification of the letters. In the visual conditions the pathway recordings were either traced out in 1 cm line segments to reveal the shape of the letters (moving window condition) or the lines were passed behind a stationary window of 1 cm diameter. In the haptic conditions subjects’ fingers were passively guided in an analogue of the moving window condition, or were held stationary while the letter drawings were passed beneath their fingertips. Letter identification was faster in the moving window conditions but haptic and visual performance did not differ.

Symmons, M.A., Richardson, B.L., & Wuillemin, D.B.(2004). Active versus passive touch: Superiority depends more on the task than the mode. In S. Ballesteros & M. Heller (Eds) Touch Blindness and Neuroscience. Madrid: Universidad Nacional De Educacion a Distancia.

We used a new device for comparing active and passive touch that provides a high level of control over the tasks, and yet also provides freedom for the explorer. Whether one of active or passive touch was superior to the other, or whether there was equivalence was determined by the type of stimulus explored. In terms of latency and accuracy, simple raised line forms were best explored passively, multiple-element figures were best explored actively, and for abstract shapes performance in the two exploratory modes was equivalent. We suggest that cognitive factors account for these findings.

Richardson, B.L., Symmons, M.A. & Wuillemin, D.B.(2004). The relative importance of cutaneous and kinaesthetic cues in raised line drawing identification. In S. Ballesteros & M. Heller (Eds) Touch Blindness and Neuroscience. Madrid: Universidad Nacional De Educacion a Distancia.

Subjects' fingertips were guided around raised line drawings by a machine we call the Tactile Display System (TDS). The subject's task was to identify, as quickly as possible, what was depicted in the drawings. There were five conditions. In the first, subjects could feel the raised line as they were guided. In the second, guided movements were the same as in condition 1 but subjects felt only the textured paper because the raised line was absent. In the third condition, the paper was completely removed, leaving only kinesthetic cues for the identification task. In the other two conditions (cutaneous information only) the fingertip was held stationary while (a) the raised line drawing was moved beneath it (following the same pattern of movements used in the previous condition) and (b) only the textured paper was moved under the stationary fingertip. Identification of the depictions deteriorated as a function of amount of information present, but performance when kinesthetic cues alone were present, did not differ from performance when cutaneous cues alone were present. The results are discussed in relation to previous research in which the roles of kinesthetic and cutaneous cues are compared.

Richardson, B.L., Symmons, M.A., & Accardi, R. (2000) The TDS: A new device for comparing active and passive-guided touch. IEEE Transactions on Rehabilitation Engineering. 8, 414-417.

A problem when comparing active and passive tactile perception of two-dimensional (2-D) stimuli is matching the active and passive tasks on all variables except the one of interest--active versus passive touch. A new computer-controlled device--the tactile display system (TDS)--has been developed to deal with this problem. The TDS tracks an "active" subject's fingertip movements during exploration of a raised line drawing and digitally records this spatio-temporal information. It then guides a passive participant's fingertip over the same path, matching for location and speed. Any difference in performance can thus be attributed to the different conditions (active versus passive) because other variables are held constant.

Symmons, M.A., & Richardson, B.L. (2000). Raised line drawings are spontaneously explored with a single finger. Perception, 29, 621-626.

In this study we examine the strategies used by blindfolded subjects asked to freely explore raised line drawings and identify what is depicted in them. We were particularly interested in how often a single finger is spontaneously used because in several studies subjects are forced to use only one fingertip and the extent to which this restriction may depress haptic perception is unclear. The results suggest that despite a variety of strategies, people 'naturally' use single fingertips sufficiently often to allow confidence in conclusions that are based on studies imposing this restriction.

Symmons, M.A. (2000). Active versus passive tactile perception. Unpublished MSc thesis. Melbourne: Monash University.

A review of the research comparing active and passive tactile exploration reveals a lack of agreement about which is superior. Knowing which is better may help determine the best way to teach blind people how to use raised line drawings and has potential application in virtual reality development. It is suggested that the field of haptics lacks satisfactory definitions of active and passive tactile perception and that previous research contains potentially confounding variables. A new device is described and tested – the Tactile Display System (TDS) – that holds constant many of these confounding factors. The results suggest that passive exploration is superior in accuracy and latency for simple raised line drawings such as the outline of a Christmas tree or a heart, that active perception is better for more complex figures such as a three-letter word, and that there is no difference between active and passive perception for simple, abstract pictures. A possible explanation for these findings and further research to test the explanation are described. The TDS is also capable of breaking passive-guided exploration into the separate components of kinaesthesis, shear, and cutaneous information. It was found that kinaesthesis is the most important factor and that in a task of exploring raised line drawings larger than the size of the fingerpad, the primary use of cutaneous information may be to guide exploratory movements.

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