Stephen A. Hughes

Some like it hot: thermal feedback for mobile devices

Thermal stimulation is a rich, emotive and salient feedback channel that is well suited to HCI, but one that is yet to be fully investigated. Thermal feedback may be suited to environments that are too loud for audio or too bumpy for vibrotactile feedback. This paper presents two studies into how well users could detect hot and cold stimuli presented to the fingertips, the palm, the dorsal surface of the forearm and the dorsal surface of the upper arm. Evaluations were carried out in static and mobile settings. Results showed that the palm is most sensitive, cold is more perceivable and comfortable than warm and that stronger and faster-changing stimuli are more detectable but less comfortable. Guidelines for the design of thermal feedback are outlined, with attention paid to perceptual and hedonic factors.

Stane: synthesized surfaces for tactile input

Stane is a hand-held interaction device controlled by tactile input: scratching or rubbing textured surfaces and tapping. The system has a range of sensors, including contact microphones, capacitive sensing and inertial sensing, and provides audio and vibrotactile feedback. The surface textures vary around the device, providing perceivably different textures to the user. We demonstrate that the vibration signals generated by stroking and scratching these surfaces can be reliably classified, and can be used as a very cheaply manufacturable way to control different aspects of interaction. The system is demonstrated as a control for a music player.

Baby it's cold outside: the influence of ambient temperature and humidity on thermal feedback

Thermal feedback is a new area of research in HCI and, as such, there has been very little investigation of the impact of environmental factors on its use for interaction. To address this shortcoming we conducted an experiment to investigate how ambient temperature and humidity could affect the usability of thermal feedback. If environmental conditions affect perception significantly, then it may not be suitable for mobile interactions. Evaluations were conducted outdoors in varying environmental conditions over a period of 5 months. Results showed that the ambient temperature has a significant impact on peoples ability to detect stimuli and also their perception of these stimuli. Humidity has a negligible effect for most humidity values. Despite this, previous thermal feedback design recommendations still hold in varying temperatures and humidities showing that thermal feedback is a useful tool for mobile interaction.

28 frames later: predicting screen touches from back-of-device grip changes

We demonstrate that front-of-screen targeting on mobile phones can be predicted from back-of-device grip manipulations. Using simple, low-resolution capacitive touch sensors placed around a standard phone, we outline a machine learning approach to modelling the grip modulation and inferring front-of-screen touch targets. We experimentally demonstrate that grip is a remarkably good predictor of touch, and we can predict touch position 200ms before contact with an accuracy of 18mm.

Augmenting media with thermal stimulation

Thermal interfaces are a new area of research in HCI, with one of their main benefits being the potential to influence emotion. To date, studies investigating thermal feedback for affective interaction have either provided concepts and prototypes, or looked at the affective element of thermal stimuli in isolation. This research is the first to look in-depth at how thermal stimuli can be used to influence the perception of different media. We conducted two studies which looked at the effect of thermal stimuli on subjective emotional responses to media. In the first we presented visual information designed to evoke emotional responses in conjunction with different thermal stimuli. In the second we used different methods to present thermal stimuli in conjunction with music. Our results highlight the possibility of using thermal stimuli to create more affective interactions in a variety of media interaction scenarios.

The effect of clothing on thermal feedback perception

Thermal feedback is a new area of research in HCI. To date, studies investigating thermal feedback for interaction have focused on virtual reality, abstract uses of thermal output or on use in highly controlled lab settings. This paper is one of the first to look at how environmental factors, in our case clothing, might affect user perception of thermal feedback and therefore usability of thermal feedback. We present a study into how well users perceive hot and cold stimuli on the hand, thigh and waist. Evaluations were carried out with cotton and nylon between the thermal stimulators and the skin. Results showed that the presence of clothing requires higher intensity thermal changes for detection but that these changes are more comfortable than direct stimulation on skin.

Perception of thermal stimuli for continuous interaction

Thermal stimulation represents a relatively unexplored and potentially beneficial area of research for interface design. To date no research on thermal interfaces has looked at continuous thermal stimulation in detail. Here we begin to explore the design space offered by continuous thermal stimulation by conducting a controlled experiment that investigates perception of various thermal stimuli relative to a range of starting temperatures. Based on the experimental results, we discuss design implications and possible future work.

Rub the stane

Stane is a hand-held interaction device controlled by tactile input: scratching or rubbing textured surfaces and tapping. The system has a range of sensors, including contact microphones, capacitive sensing and inertial sensing, and provides audio and vibrotactile feedback. The surface textures vary around the device, providing perceivably different textures to the user. We demonstrate that the vibration signals generated by stroking and scratching these surfaces can be reliably classified, and can be used as a very cheap to manufacture way to control different aspects of interaction. The system is demonstrated as a control for a music player, and in a mobile spatial interaction scenario.