KUSUGURI: Visual Tactile Integration for TicklingMasahiro Furukawa1, Hiroyuki Kajimoto2, Susumu Tachi1
Keio University, 2The University of Electro-Communications

1

Figure 1 Remote tickling with video chat (left). Users can observe a moving fingertip, which looks likesomeone is actually tickling the palm with his/her fingertip (center). Tickling as a physical contact (right).

1. Introduction

3. Design and Implementation

Tickling as physical contact plays an important role in close
relationships [Provine 2004]. Whereas a mobile phone andvideo chat are commonly used for remote communication,
remote tickling is seldom used for physical contact.

Pre-captured palm and fingertip images are stored in the device(an Apple iPod touch 3rd Gen., 32 GB model). The device isplaced in such a way as to suit the displayed palm image asshown in Figure 1 (center). Once the touch panel of the device
measures movement of the fingertip when one user tickles
another with the device as shown in Figure 1 (right), themovement is sent wirelessly to another device in real time. The
touch panel does not receive an actual tactile sensation; only thefingertip’s movement.

It is necessary to producing a tickling sensation to realize remotetickling. For instance, a tactile display used in network gaming,
tickles the wearer’s midriff via an unpredictable anduncontrollable vibration [Tsetserukou 2010]. Such a tactile
display, where the tactile sensation is produced by a mechanicalapproach, however, tends to be larger and less portable becausea tactile sensation is required to induce the tickling sensation. In
this paper, we propose a remote tickling method using visual
tactile integration that is easily achievable with the existingtelecommunication infrastructure.

2. Principle of Perception
The proposed method is based on an illusion we discovered:simple vibration, which does not induce a tickling sensation by
itself, is perceived as tickling when accompanied by a moving
visual cue. It is widely known that a tickling sensation can befelt simply by watching a tickle gesture close to our body,
regardless of whether there is physical contact. In addition, anacoustic cue produced close to our ears also evokes a ticklingsensation [Kitagawa 2010].
We focus on the palm, which is suitable for physical contact asshown in Figure 1 (right), and propose a method that includes avisual tactile display, appearing as a continuation of the palm asshown in Figure 1 (center). Users can observe a moving
fingertip, which looks like someone is actually tickling the palm
with his/her fingertip, while feeling a simple and slight vibration
provided by the device during the tickling. As a result, users
perceive a tickling sensation due to the sensory integration of
the visual cue from the movement of the fingertip and the tactile
cue from the simple vibration.
Furthermore, our proposed method also enables bidirectional
tickling using the same device, and is expected to be applied
widely to other parts of the body, on which the device can easily
be placed.

Copyright is held by the author / owner(s).
SIGGRAPH Asia 2011, Hong Kong, China, December 12 – 15, 2011.
ISBN 978-1-4503-0807-6/11/0012

The device receiving the movement of the fingertip generates anaudio signal amplitude-modified and proportional to the velocityof the finger (Figure 2 (left)). The vibration is provided by avibrator attached to the rear of the device as shown in Figure 2(right), and amplified with an audio amp. For practicalapplication, the pre-captured images are obtained using theinternal camera of the smartphone and exchanged via a network,
while an internal vibrator is used instead of the attached vibrator
and audio amp.

Figure 2 Vibration synchronized with velocity of the finger

REFERENCES
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pp.215-218, 2004
Tsetserukou, D. and Neviarouskaya, A.: World's first wearable
humanoid robot that augments our emotions. In Proceedingsof the 1st Augmented Human International Conference (AH'10), pp.1-10, 2010
Kitagawa, N. and Spence, C.: Audiotactile multisensory
interactions in human information processing, Japanese
Psychol. Research, Volume 48, No. 3, pp.158–173, 2006