Abstract: |
In this paper we present the results of the study focused on the uncanny valley effect for the hand prosthetics. The motivation for this study comes directly from the author of the uncanny valley hypothesis who illustrated the very idea with the hand prosthetics (Mori et al., 2012, p. 99). Number of studies concerning the UV effect for hand prosthetics is still relatively low (e.g. Poliakoff et al., 2018; Buckingham et al., 2019), thus we aimed to enrich this field.
We were also interested in a more general question related to UV studies. In most cases the stimuli presented to subjects are static pictures (as in the aforementioned ones). However, one may expect that the way you would present the stimuli will affect its evaluation. We have addressed this issue in our study.
We have designed a study with three types of stimuli: human hand (H), prosthetic (P): “Tolka” by the vBionic company and robotic hand (R): “Tolka” without the artificial skin. These stimuli were presented in three experimental conditions: (G1) Photo; (G2) Photo sequence and (G3) Video. For (G2) and (G3) respective stimuli were presented during actions: pointing (a page in a book); grasping (a card lying on the table) and moving (a mug towards a subject). Subjects were asked to evaluate how human-like is the presented hand; how eerie is the presented hand; how much they like the presented hand and to decide whether the hand is natural or artificial. Our research questions were: 1) Will we observe the UV effect for (P) and 2) Will we observe differences in the stimuli evaluations between G1, G2 and G3.
The study was conducted online. 94 participants (49 women), aged 18-72; average 28.42 (SD=9.89) took part. No UV effect for (P) is observed. There are significant differences between G1, G2 and G3 for the (P) stimuli. For G3 prosthetic hand has the lowest human-likeness assessment, lowest like level and the highest eeriness evaluation. Stimuli presentation method does not affect the evaluation of (H) and (R).
The results are important for the UV studies field as they present the evaluation of an actual, commercially available prosthetic hand. What is more, they clearly suggest that the way the stimuli is presented for such studies affect its evaluation - such knowledge should be used for designing future studies.
Several limitations of this study should be also addressed. First of all the study group was relatively small and should be extended for the stronger results. We also believe that future study should also involve real-life interaction with the used stimuli.
References: (1) Buckingham, G., Parr, J., Wood, G., Day, S., Chadwell, A., Head, J. & Poliakoff, E. (2019). Upper-and lower-limb amputees show reduced levels of eeriness for images of prosthetic hands. Psychonomic Bulletin & Review, 26, 1295-1302.
(2) Mori, M., MacDorman, K. F., and Kageki, N. (2012). The uncanny valley [from the field]. IEEE Robotics & Automation Magazine, 19(2):98-100.
(3) Poliakoff, E., O’Kane, S., Carefoot, O., Kyberd, P., and Gowen, E. (2018). Investigating the uncanny valley for prosthetic hands. Prosthetics and orthotics international, 42(1):21-27. |