Mark Symmons

Raised line drawings are spontaneously explored with a single finger.

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.

Components of Haptic Information: Skin Rivals Kinaesthesis

Four components of the haptic system were investigated, in isolation and in various combinations, during passive-guided exploration of raised-line drawings. The components were kinaesthesis, cutaneous input from the presence of a raised line, shear forces from relative movement between the skin and a textured surface, and attenuated distortions at the fingertip resulting from relative movement between the fingertip and a surface. Although the presence of kinaesthetic information was found to be positively correlated with performance in a task of identifying raised-line letters, conditions involving touch alone yielded performance equivalent to that when kinaesthesis was involved. Together, these results suggest that tactile information could be as effective as kinaesthetic information. The results are discussed in terms of applications to the design of human – machine interfaces.

Haptic and visual size judgements in virtual and real environments

In a series of 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 of various sizes that could be both viewed and touched. Virtual spheres were presented using a Phantom for the haptic presentations or a 4D 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.

Intrasensory attention: kinaesthetic versus cutaneous inputs.

Blindfolded participants felt pairs of raised-line drawings simultaneously, one with each index finger. The stimuli presented at each fingertip were 180° rotations of each other (eg 6 and 9). One finger moved (either actively or passively), and this in turn caused movement of a matched raised line underneath the stationary finger on the other hand, in a yoked manner. Thus, a 6 at the moving finger would be felt as a 9 on the stationary finger. On all trials there was a raised line moving underneath the stationary fully passive finger. For the moving finger, a raised line was present on only half of the trials. When a raised line could be felt at the moving fingertip, the shape followed by this finger was more often reported than was the shape present at the other (stationary) fingertip. However, when no line was present under the moving finger (ie when movement became the major cue for shape), subjects reported experiencing the shape moved under the stationary fingertip. Results are interpreted as an indication that cutaneous information can be more ‘attention-getting’ than kinaesthetic information, and are considered to support the modality-appropriateness theory.

Visual and haptic influence on perception of stimulus size

In six experiments, subjects judged the sizes of squares that were presented visually and/or haptically, in unimodal or bimodal conditions. We were interested in which mode most affected size judgments in the bimodal condition when the squares presented to each mode actually differed in size. Three factors varied: whether haptic exploration was passive or active, whether the choice set from which the subjects selected their responses was visual or haptic, and whether cutaneous information was provided in addition to kinesthetic information. To match the task for each mode, visual presentations consisted of a cursor that moved along a square pathway to correspond to the haptic experience of successive segments revealed during exploration. We found that the visual influence on size judgments was greater than the influence of haptics when the haptic experience involved only kinesthesis, passive movement, and a visual choice set. However, when cutaneous input was added to kinesthetic information, size judgments were most influenced by the haptic mode. The results support hypotheses of sensory integration, rather than capture of one sense by the other.

Modification of Magnitude Estimations in Thermotactile Perception during Self-Generated and Externally Generated Movements

Fourteen participants felt a ‘cold’ stimulus move across a fingertip. When movement was self-controlled, the stimulus was reported as feeling less ‘cold’ than when movement was externally generated.

Population based case–control study of serious non-fatal motorcycle crashes

BackgroundMotorcycle sales, registration and use are increasing in many countries. The epidemiological literature on risk factors for motorcycle injury is becoming outdated, due to changes in rider demography, licensing regulations, traffic mix and density, road environments, and motorcycle designs and technologies. Further, the potential contribution of road infrastructure and travel speed has not yet been examined.Methods/designA population based case–control study together with a nested case-crossover study is planned. Cases will be motorcycle riders who are injured but not killed in a motorcycle crash on a public road within 150 km radius of Melbourne, Australia, and admitted to one of the study hospitals. Controls will be motorcycle riders who ride through the crash site on the same type of day (weekday or weekend) within an hour of the crash time. Data on rider, bike, and trip characteristics will be collected from the participants by questionnaire. Data on crash site characteristics will be collected in a structured site inspection, and travel speed for the cases will be estimated from these data. Travel speed for the controls will be measured prior to recruitment with a radar traffic detection device as they ride through the crash site. Control sites for the case-crossover study will be selected 1 km upstream from the crash site and matched on either intersection status or road curvature (either straight or cornered). If the initial site selected does not match the case site on these characteristics, then the closest matching site on the case route will be selected. Conditional multivariate logistic regression models will be used to compare risk between the matched case and control riders and to examine associations between road infrastructure and road environment characteristics and crash occurrence. Interactions between type of site and speed will be tested to determine if site type is an effect modifier of the relationship between speed and crash risk. The relationship between rider factors and travel speed generally will be assessed by multivariate regression methods.DiscussionIn the context of the changing motorcycling environment, this study will provide evidence on contemporary risk factors for serious non-fatal motorcycle crashes.

The contribution of virtual reality to research on sensory feedback in remote control

Here we consider research on the kinds of sensory information most effective as feedback during remote control of machines, and the role of virtual reality and telepresence in that research. We argue that full automation is a distant goal and that remote control deserves continued attention and improvement. Visual feedback to controllers has developed in various ways but autostereoscopic displays have yet to be proven. Haptic force feedback, in both real and virtual settings, has been demonstrated to offer much to the remote control environment and has led to a greater understanding of the kinesthetic and cutaneous components of haptics, and their role in multimodal processes, such as sensory capture and integration. We suggest that many displays using primarily visual feedback would benefit from the addition of haptic information but that much is yet to be learned about optimizing such displays.

Cutaneous inputs yield judgments of line length that are equal to, or better than, those based on kinesthetic inputs

An experiment was designed to investigate haptic perception of length depending on whether inputs were cutaneous or derived from passively-guided movements. Cutaneous inputs appeared to offer more accurate information than did those from kinesthesis. Our results are inconsistent with the view that, for identification of raised line drawings, kinesthetic inputs are more important than tactile inputs.

The more they move the less they know: Cutaneous capture of kinesthesis?

Blindfolded participants felt pairs of “rivalrous” stimuli simultaneously, one with each index finger. The stimuli presented at each fingertip were 180° rotations of each other (e.g. <; and >;). Participants moved one index finger which caused a raised line to move underneath the other, stationary, index finger, in a yoked manner. Thus, when a <; was traced with the moving finger it caused a >; to be felt at the stationary finger. On all trials there was a raised line moving underneath the stationary finger. For the moving finger, a raised line was present on only one-third of the trials. When a raised line could be felt at the moving fingertip, the angle followed by this finger was invariably reported in conjunction with the angle present at the other (stationary) fingertip. However, when no line was present under the moving finger (i.e. when movement became the major cue for shape), participants almost always reported experiencing only the angle presented to the stationary fingertip - capturing the angle followed by the moving finger. Results are interpreted in light of optimal integration, bistable figures and inattentional blindness.