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Consumed Endurance: A Metric to Quantify Arm Fatigue of Mid-Air Interactions

Mid-air interactions are prone to fatigue and lead to a feeling of heaviness in the upper limbs, a condition casually termed as the gorilla-arm effect. Designers have often associated limitations of their mid-air interactions with arm fatigue, but do not possess a quantitative method to assess and therefore mitigate it. In this paper we propose a novel metric, Consumed Endurance (CE), derived from the biomechanical structure of the upper arm and aimed at characterizing the gorilla-arm effect. We present a method to capture CE in a non-intrusive manner using an off-the-shelf camera-based skeleton tracking system, and demonstrate that CE correlates strongly with the Borg CR10 scale of perceived exertion. We show how designers can use CE as a complementary metric for evaluating existing and designing novel mid-air interactions, including tasks with repetitive input such as mid-air text-entry. Finally, we propose a series of guidelines for the design of fatigue-efficient mid-air interfaces.


You can download the CE workbench on GitHub:


Hincapié-Ramos, J.D., Guo, X., Moghadasian, P. and Irani, P. 2014. Consumed endurance: a metric to quantify arm fatigue of mid-air interactions. In Proceedings of the 32nd annual ACM conference on Human factors in computing systems (CHI '14). ACM

Bibtext Entry

author = {Hincapi{\'e}-Ramos, Juan David and Guo, Xiang and Moghadasian, Paymahn and Irani, Pourang},
title = {Consumed Endurance: A Metric to Quantify Arm Fatigue of Mid-air Interactions},
booktitle = {Proceedings of the SIGCHI Conference on Human Factors in Computing Systems},
series = {CHI '14},
year = {2014},
isbn = {978-1-4503-2473-1},
location = {Toronto, Ontario, Canada},
pages = {1063--1072},
numpages = {10},
url = {http://doi.acm.org/10.1145/2556288.2557130},
doi = {10.1145/2556288.2557130},
acmid = {2557130},
publisher = {ACM},
address = {New York, NY, USA},
keywords = {consumed endurance, endurance, gorilla-arm, mid-air interactions, mid-air text-entry, seato mid-air keyboard},

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Consumed Endurance


Jango Guo

Jango Guo

Pourang Irani

Pourang Irani

Canada Research Chair
at University of British Columbia Okanagan Campus