This tutorial focuses on the sense of touch within the context of a fully active human observer. It is intended for graduate students and researchers outside the discipline who seek an introduction to the rapidly evolving field of human haptics. The tutorial begins with a review of peripheral sensory receptors in skin, muscles, tendons, and joints. We then describe an extensive body of research on “what” and “where” channels, the former dealing with haptic perception of objects, surfaces, and their properties, and the latter with perception of spatial layout on the skin and in external space relative to the perceiver. We conclude with a brief discussion of other significant issues in the field, including vision-touch interactions, affective touch, neural plasticity, and applications.

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Haptic perception: a tutorial.

This paper reviews a theory of causal inference based on the Structural Causal Model (SCM) described in (Pearl, 2000a). The theory unifies the graphical, potential-outcome (Neyman-Rubin), decision analytical, and structural equation approaches to causation, and provides both a mathematical foundation and a friendly calculus for the analysis of causes and counterfactuals. In particular, the paper establishes a methodology for inferring (from a combination of data and assumptions) the answers to three types of causal queries: (1) queries about the effect of potential interventions, (2) queries about counterfactuals, and (3) queries about the direct (or indirect) effect of one event on another.

What is Causal Inference

Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems 参加報告

https://dspace.library.uu.nl/bitstream/handle/1874/204059/panda.pdf?sequence=3

Tactual perception of material properties

Various psychophysical methods have been used to study human haptic perception, although the selection of a particular method is often based on convention, rather than an analysis of which technique is optimal for the question being addressed. In this review, classical psychophysical techniques used to measure sensory thresholds are described as well as more modern methods such as adaptive procedures and those associated with signal detection theory. Details are provided as to how these techniques should be implemented to measure absolute and difference thresholds and factors that influence subjects' responses are noted. In addition to the methods used to measure sensory thresholds, the techniques available for measuring the perception of suprathreshold stimuli are presented. These scaling methods are reviewed in the context of the various stimulus and response biases that influence how subjects respond to stimuli. The importance of understanding the factors that influence perceptual processing is highlighted throughout the review with reference to experimental studies of haptic perception.

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Application of Psychophysical Techniques to Haptic Research

Thermal displays have been developed to present thermal cues to the hand to facilitate object recognition in virtual environments or in teleoperated robotic systems. This review focuses on this application domain of thermal displays and considers the models developed to simulate the thermal interaction between an object and the hand as they make contact. An overview of thermal perception and the mechanisms underlying the processing of thermal information is provided to give a framework for analyzing the design of thermal displays. The models developed to simulate thermal feedback are examined together with a description of the implementation of these models in thermal displays. The domains in which thermal displays have been used are described; this includes the simulation of material properties, the recreation of large-scale thermal effects in virtual environments, the encoding of abstract concepts and the use of thermal feedback in interactive art. The review concludes by considering the advantages and challenges associated with using thermal displays in these diverse areas.

Warm or Cool, Large or Small? The Challenge of Thermal Displays

The objective of these two experiments was to determine the role of thermal cues in material discrimination and localization, using materials that spanned a range of thermal properties. In the first experiment, the subjects were required to select the cooler of two materials presented to the index fingers. In the second, the finger that was in contact with a material that was different from that presented to the other two fingers on the same hand had to be identified. The results indicated that the subjects were able to discriminate between materials, using thermal cues, when the differences in their thermal properties were large. The changes in skin temperature when the fingers were touching the materials were, however, smaller than those predicted by the theoretical model. The ability to localize the thermal changes when three fingers on the same hand were stimulated was poor and depended on both the thermal properties of the target and the distractor materials.

/pdf/contribution-of-thermal-cues-to-material-discrimination-and-15ef0qdc95.pdf

Contribution of thermal cues to material discrimination and localization

In our daily lives, information concerning temperature is often provided by means of colour cues, with red typically being associated with warm/hot, and blue with cold. While such correspondences have been known about for many years, they have primarily been studied using subjective report measures. Here we examined this correspondence using two more objective response measures. First, we used the Implicit Association Test (IAT), a test designed to assess the strength of automatic associations between different concepts in a given individual. Second, we used a priming task that involved speeded target discrimination in order to assess whether priming colour or thermal information could invoke the crossmodal association. The results of the IAT confirmed that the association exists at the level of response selection, thus indicating that a participant’s responses to colour or thermal stimuli are influenced by the colour-temperature correspondence. The results of the priming experiment revealed that priming a colour affected thermal discrimination reaction times (RTs), but thermal cues did not influence colour discrimination responses. These results may therefore provide important clues as to the level of processing at which such colour-temperature correspondences are represented.

/pdf/colour-temperature-correspondences-when-reactions-to-thermal-3sdzrw8w0x.pdf

Colour-temperature correspondences: when reactions to thermal stimuli are influenced by colour.

The objective of this study was to develop and evaluate a thermal display that assists in object identification in virtual environments by simulating the thermal cues associated with making contact with materials with different thermal properties. The thermal display was developed based on a semi-infinite body model. Three experiments were conducted to evaluate the performance of the display. The first experiment compared the ability of subjects' to identify various materials, which were presented physically or simulated with the thermal display. The second experiment examined the capacity of subjects to discriminate between a real and simulated material based on thermal cues. In the third experiment, the changes in skin temperature that occurred when making contact with real and simulated materials were measured to evaluate how these compare to theoretical predictions. The results indicated that there was no significant difference in material identification and discrimination when subjects were presented with real or simulated materials. The changes in skin temperature were comparable for real and simulated materials and were related to the contact coefficient of the material palpated, consistent with the semi-infinite body model. These findings suggest that a thermal display is capable of facilitating object recognition when visual cues are limited.

Development and evaluation of a thermal display for material identification and discrimination

The objective of this research is to analyze and model the decreases in skin temperature when the hand makes contact with an object at room temperature so that thermal feedback can be incorporated into haptic displays. A thermal model is proposed that predicts the thermal responses of the skin and object surface as well as the heat flux exchanged during hand-object interactions. The model was evaluated by comparing the theoretical predictions of temperature changes to those experimentally measured using an infrared thermal measurement system. The thermal measurement system was designed to overcome the limitations imposed by contact thermal sensors, and was able to measure skin temperature during contact, together with the contact area and contact force. The experimental results indicated that over the pressure range of 0.73-10.98 kPa, changes in skin temperature were well localized to the contact area and were affected by contact pressure. The pressure in turn influenced both thermal contact resistance and blood flow. Over the range of contact forces typically used in manual exploration, blood perfusion and metabolic heat generation do not appear to have a significant effect on the skin's thermal responses. The theoretical predictions and the measured data were consistent in characterizing the time course and amplitude of the skin temperature change during contact with differences typically being less than 1 degrees C between the two for pressures greater than 4 kPa. These findings indicate that the proposed thermal model is able to characterize and predict the skin temperature responses during hand-object interactions and could be used in a thermal display that simulates the properties of different materials.

Hsin-Ni Ho

Papers

Warm or Cool, Large or Small? The Challenge of Thermal Displays

Contribution of thermal cues to material discrimination and localization

Colour-temperature correspondences: when reactions to thermal stimuli are influenced by colour.

Development and evaluation of a thermal display for material identification and discrimination

Modeling the thermal responses of the skin surface during hand-object interactions.