Jussi Rantala

Emotional and behavioral responses to haptic stimulation

A prototype of friction-based horizontally rotating fingertip stimulator was used to investigate emotional experiences and behavioral responses to haptic stimulation. The rotation style of 12 different stimuli was varied by burst length (i.e., 20, 50, 100 ms), continuity (i.e., continuous and discontinuous), and direction (e.g., forward and backward). Using these stimuli 528 stimulus pairs were presented to 12 subjects who were to distinguish if stimuli in each pair were the same or different. Then they rated the stimuli using four scales measuring the pleasantness, arousal, approachability, and dominance qualities of the 12 stimuli. The results showed that continuous forward-backward rotating stimuli were rated as significantly more unpleasant, arousing, avoidable, and dominating than other types of stimulations (e.g., discontinuous forward rotation). The reaction times to these stimuli were significantly faster than reaction times to discontinuous forward and backward rotating stimuli. The results clearly suggest that even simple haptic stimulation can carry emotional information. The results can be utilized when making use of haptics in human-technology interaction.

Methods for Presenting Braille Characters on a Mobile Device with a Touchscreen and Tactile Feedback

Three novel interaction methods were designed for reading six-dot Braille characters from the touchscreen of a mobile device. A prototype device with a piezoelectric actuator embedded under the touchscreen was used to create tactile feedback. The three interaction methods, scan, sweep, and rhythm, enabled users to read Braille characters one at a time either by exploring the characters dot by dot or by sensing a rhythmic pattern presented on the screen. The methods were tested with five blind Braille readers as a proof of concept. The results of the first experiment showed that all three methods can be used to convey information as the participants could accurately (91-97 percent) recognize individual characters. In the second experiment the presentation rate of the most efficient and preferred method, the rhythm, was varied. A mean recognition accuracy of 70 percent was found when the speed of presenting a single character was nearly doubled from the first experiment. The results showed that temporal tactile feedback and Braille coding can be used to transmit single-character information while further studies are still needed to evaluate the presentation of serial information, i.e., multiple Braille characters.

Gaze gestures and haptic feedback in mobile devices

Anticipating the emergence of gaze tracking capable mobile devices, we are investigating the use of gaze as an input modality in handheld mobile devices. We conducted a study of combining gaze gestures with vibrotactile feedback. Gaze gestures were used as an input method in a mobile device and vibrotactile feedback as a new alternative way to give confirmation of interaction events. Our results show that vibrotactile feedback significantly improved the use of gaze gestures. The tasks were completed faster and rated easier and more comfortable when vibrotactile feedback was provided.

Touch gestures in communicating emotional intention via vibrotactile stimulation

Remote communication between people typically relies on audio and vision although current mobile devices are increasingly based on detecting different touch gestures such as swiping. These gestures could be adapted to interpersonal communication by using tactile technology capable of producing touch stimulation to a users hand. It has been suggested that such mediated social touch would allow for new forms of emotional communication. The aim was to study whether vibrotactile stimulation that imitates human touch can convey intended emotions from one person to another. For this purpose, devices were used that converted touch gestures of squeeze and finger touch to vibrotactile stimulation. When one user squeezed his device or touched it with finger(s), another user felt corresponding vibrotactile stimulation on her device via four vibrating actuators. In an experiment, participant dyads comprising a sender and receiver were to communicate variations in the affective dimensions of valence and arousal using the devices. The senders task was to create stimulation that would convey unpleasant, pleasant, relaxed, or aroused emotional intention to the receiver. Both the sender and receiver rated the stimulation using scales for valence and arousal so that the match between senders intended emotions and receivers interpretations could be measured. The results showed that squeeze was better at communicating unpleasant and aroused emotional intention, while finger touch was better at communicating pleasant and relaxed emotional intention. The results can be used in developing technology that enables people to communicate via touch by choosing touch gesture that matches the desired emotion.

The Role of Gesture Types and Spatial Feedback in Haptic Communication

The sense of touch is a fundamental part of social interaction as even a short touch from another person can elicit emotional experiences. Previous studies on haptic communication indicate that the benefits of interpersonal touch exist even when touch is artificially mediated between people that are physically apart. In the current study an evaluation of three input gestures (i.e., moving, squeezing, and stroking) was conducted to identify preferred methods for creating haptic messages using a hand-held device. Furthermore, two output methods (i.e., one or four haptic actuators) were investigated in order to determine whether representing spatial properties of input gestures haptically provides additional benefit for communication. Participants created haptic messages in four example communication scenarios. The results of subjective ratings, postexperimental interviews, and observations showed that squeezing and stroking were the preferred ways to interact with the device. Squeezing was an unobtrusive and quick way to create haptic content. Stroking, on the other hand, enabled crafting of more detailed haptic messages. Spatial haptic output was appreciated especially when using the stroking method. These findings can help in designing haptic communication methods for hand-held devices.

Haptically augmented remote speech communication: a study of user practices and experiences

Haptic technology provides a channel for interpersonal communication through the sense of touch. In the development of novel haptic communication devices, it is essential to explore peoples use behaviors and perceptions of such a communication channel. To this end, we conducted a laboratory study on haptically augmented remote interpersonal communication. Participant pairs tested a communication system that allowed them to send squeezing and thermal feedback to each others forearm during speech discussion. We explored the use practices and user experience of this setup and compared it to traditional speech-only communication. The findings indicate that squeezing was experienced as a more versatile and immediate type of feedback than thermal feedback. Warm and cold were on the other hand useful for communicating positive and negative meanings. Compared to speech-only communication, the added haptic modality allowed conveying emphases, emotions, and touches related to the discussion, and increased the feeling of closeness between the pairs.

Perception of low-amplitude haptic stimuli when biking

Haptic stimulation in motion has been studied only little earlier. To provide guidance for designing haptic interfaces for mobile use we carried out an initial experiment using C-2 actuators. 16 participants attended in the experiment to find out whether there is a difference in perceiving low-amplitude vibrotactile stimuli when exposed to minimal and moderate physical exertion. A stationary bike was used to control the exertion. Four body locations (wrist, leg, chest and back), two stimulus durations (1000 ms and 2000 ms) and two motion conditions with the stationary bicycle (still and moderate pedaling) were applied. It was found that cycling had significant effect on both the perception accuracy and the reaction times with selected stimuli. Stimulus amplitudes used in this experiment can be used to help haptic design for mobile users.

Delivering directional haptic cues through eyeglasses and a seat

Navigation systems usually require visual or auditory attention. Providing the user with haptic cues could potentially decrease cognitive demand in navigation. This study is investigating the use of haptic eyeglasses in navigation. We conducted an experiment comparing directional haptic cues to visual cueing in a car navigation task. Participants (N=12) drove the Lane Change Test simulator with visual text cues, haptic cues given by the eyeglasses and haptic cues given by a car seat. The participants were asked to confirm the recognition of a directional cue (left or right) by pressing an arrow on a tablet screen and by navigating to the corresponding lane. Reaction times and errors were measured. The participants filled in the NASA-TLX questionnaire and were also interviewed about the different cues. The results showed that in comparison to the visual text cues the haptic cues were reacted to significantly faster. Haptic cueing was also evaluated as less frustrating than visual cueing. The haptic eyeglasses fared slightly, although not significantly, better than the haptic seat in subjective and objective evaluations. The paper suggests that haptic eyeglasses can decrease cognitive demand in navigation and have many possible applications.

Accessible Multimodal Media Center Application for Blind and Partially Sighted People

We present a multimodal media center interface designed for blind and partially sighted people. It features a zooming focus-plus-context graphical user interface coupled with speech output and haptic feedback. A multimodal combination of gestures, key input, and speech input is utilized to interact with the interface. The interface has been developed and evaluated in close cooperation with representatives from the target user groups. We discuss the results from longitudinal evaluations that took place in participants’ homes, and compare the results to other pilot and laboratory studies carried out previously with physically disabled and nondisabled users.

Enhancing personal communication with spatial haptics: Two scenario-based experiments on gestural interaction

Haptic gestures and sensations through the sense of touch are currently unavailable in remote communication. There are two main reasons for this: good quality haptic technology has not been widely available and knowledge on the use of this technology is limited. To address these challenges, we studied how users would like to, and managed to create spatial haptic information by gesturing. Two separate scenario-based experiments were carried out: an observation study without technological limitations, and a study on gesturing with a functional prototype with haptic actuators. The first study found three different use strategies for the device. The most common gestures were shaking, smoothing and tapping. Multimodality was requested to create the context for the communication and to aid the interpretation of haptic stimuli. The second study showed that users were able to utilize spatiality in haptic messages (e.g., forward-backward gesture for agreement). However, challenges remain in presenting more complex information via remote haptic communication. The results give guidance for communication activities that are usable in spatial haptic communication, and how to make it possible to enable this form of communication in reality.