Mariacarla Memeo

The Importance of Visual Experience, Gender, and Emotion in the Assessment of an Assistive Tactile Mouse

Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually impaired people. Their limited adaptability can be compensated with haptic devices which display graphical information, but their assessment is frequently limited to performance-based metrics only which can hide potential spatial abilities in O&M protocols. We assess a low-tech tactile mouse able to deliver three-dimensional content considering how performance, mental workload, behavior, and anxiety status vary with task difficulty and gender in congenitally blind, late blind, and sighted subjects. Results show that task difficulty coherently modulates the efficiency and difficulty to build mental maps, regardless of visual experience. Although exhibiting attitudes that were similar and gender-independent, the females had lower performance and higher cognitive load, especially when congenitally blind. All groups showed a significant decrease in anxiety after using the device. Tactile graphics with our device seems therefore to be applicable with different visual experiences, with no negative emotional consequences of mentally demanding spatial tasks. Going beyond performance-based assessment, our methodology can help with better targeting technological solutions in orientation and mobility protocols.

Characterization of nonlinear finger pad mechanics for tactile rendering

The computation of skin forces and deformations for tactile rendering requires an accurate model of the extremely nonlinear behavior of the skin. In this work, we investigate the characterization of finger mechanics with the goal of designing accurate nonlinear models for tactile rendering. First, we describe a measurement setup that enables the acquisition of contact force and contact area in the context of controlled finger indentation experiments. Second, we describe an optimization procedure that estimates the parameters of strain-limiting deformation models that match best the acquired data. We show that the acquisition setup allows the measurement of force and area information with high repeatability, and the estimation method reaches nonlinear models that match the measured data with high accuracy.

Similarity of Blind and Sighted Subjects When Constructing Maps with Small-Area Tactile Displays: Performance, Behavioral and Subjective Aspects

Conveying spatial information to visually impaired people is possible by leveraging residual tactile abilities. It is still unclear how to effectively evaluate mental map construction beyond performance-based metrics. Here we use a minimalistic mouse-shaped tactile device to display tactile virtual objects. We study how task complexity and visual deprivation influence behavioral, subjective and performance variables both in blind and sighted subjects. Complexity shows to be a factor equally affecting both groups. As well we show that performance, amount of acquired information and subjective judgments of task difficulty do not depend on visual deprivation. Results can help with technological solutions in rehabilitation programs for impaired individuals.

How Geometrical Descriptors Help to Build Cognitive Maps of Solid Geometry with a 3DOF Tactile Mouse

In this work we study how the kind and number of geometrical descriptors affects the way real objects are matched to virtual 2.5D objects, rendered with a 3DOF tactile mouse. We show that elevation or inclination cues are sufficient to recognize a small tactile dictionary of geometrical solids, but that their combination works at best. We also show that inclination alone may generate confusion and elicits the highest perceived cognitive load. Our setup can be the basis to build tactile user desktop interfaces to facilitate learning of mathematical concepts for people with vision loss.

Do Blind Subjects Differ from Sighted Subjects When Exploring Virtual Tactile Maps

The access to graphical information is difficult for individuals who are blind or visually impaired. Taking advantage of the residual sensory abilities such as touch is one way to solve this issue. However, it is not yet clear if blind subjects perceive new tacto-spatial information in the same way that sighted people do. In this work we code the discovery of unknown tactile virtual objects in terms of subjective and behavioral variables, which result to be in-dependent on visual deprivation and dependent only on task difficulty. Our methodology can be employed in educational, orientation and mobility protocols.

Tactile sensibility through tactile display: effect of the array density and clinical use

Sensing in humans is carried out in different modalities, among them, the touch is essential in every-day life allowing most of all the manual activities. Less known is the fundamental role in the screening of some neurological diseases. In fact it is possible, trough the assessment of the level of tactile perception, to evaluate during clinical/medical diagnosis the nervous systemhealth state. It is therefore fundamental to determine valid measurement procedures aiming to this task. The analysis has started with the investigation of tactile frequency sensibility, on healthy subjects, who examined tactile stimuli with devices called arrays. Arrays are formed by passive pins, which follow the shape of the stimuli. There were different arrays depending on the number of pins on them. The only task of subjects was to recognize the higher between couples of stimuli (one grating) with different frequency. The aim of these tests is that of creating a diagnostic scale for tactile neurodegenerative syndromes and diseases. Results show a significant role of pins density with a performance that falls when pins distance is higher than 1 mm. Preliminary clinical tests on 3 patients with tunnel carpal syndrome suggest positive development for use as a diagnostic tool.

Mind the Bump: Effect of Geometrical Descriptors on the Perception of Curved Surfaces with a Novel Tactile Mouse

In this work we present a new haptic assistive device, the TActile MOuse 3 (TAMO3), designed to support construction of mental maps in absence of vision. Since curvature is a sufficient information in recognition and classification of shapes [11] we evaluate TAMO3 in a curvature discrimination task: curves were rendered, on one finger only, through geometrical descriptors such as elevation and inclination, in three degrees of freedom. We assessed how performance and mental workload were influenced by such descriptors. Inclination cues were confirmed to be associated with higher precision and higher mental demand, with no increase in frustration. Therefore, as delivered by our device, inclination seems to be an effective haptic cue to mentally construct curved virtual shapes. The joint analysis of aspects from psychophysics and workload confirms to be essential when designing assistive haptic devices since it provides different and complementary results.

Tactile Treasure Map: Integrating Allocentric and Egocentric Information for Tactile Guidance.

With interactive maps a person can manage to find the way from one point to another, using an allocentric perspective (e.g. Google Maps), but also looking at a location as from the inside of the map with an egocentric perspective (e.g. Google Street View). Such experience cannot be performed with tactile maps, mostly explored from a top-view. To solve this, we built a system with two different but complementary devices. When coupled, they can provide both allocentric and egocentric spatial information to support the exploration of interactive tactile maps. To show the potential of the system, we built a blind treasure hunt.

Dynamic Investigation Test-rig on hAptics (DITA)

Research on tactile sensitivity has been conducted since the last century and many devices have been proposed to study in detail this sense through experimental tests. The sense of touch is essential in every-day life of human beings, but it can also play a fundamental role for the assessment of some neurological disabilities and pathologies. In fact, the level of tactile perception can provide information on the health state of the nervous system. In this paper, authors propose the design and development of a novel test apparatus, named DITA (Dynamic Investigation Test-rig on hAptics), aiming to provide the measurement of the tactile sensitivity trough the determination of the Just Noticeable Difference (JND) curve of a subject. The paper reports the solution adopted for the system design and the results obtained on the set of experiments carried out on volunteers.

Laser application on haptics: Tactile stiffness measurement

There is a great interest in exploring the proprieties of the sense of the touch, its detailed knowledge in fact is a key issue in the area of robotics, haptics and human-machine interaction. In this paper, the authors focus their attention on a novel measurement method for the assessment of the tactile stiffness based on a original test rig; tactile stiffness is defined as the ratio between force, exerted by the finger, and the displacement of the finger tip operated during the test. To reach this scope, the paper describes a specific experimental test-rig used for the evaluation of subject tactile sensitivity, where finger force applied during tests as well as displacement and velocity of displacement, operated by the subject under investigation, are measured. Results show that tactile stiffness is linear respect to stimuli spatial difference (which is proportional to the difficulty to detect the variation of them). In particular, it has been possible to relate the force and displacement measured during...