Updating Fitts’ Law

1002 Words3 Pages

Interaction with small displays, from ultra-mobile PCs and smart phones to head-mounted displays, has become an integral part of the daily lives of many technology users. However, when compared to typical desktop displays, the small displays of these devices generally occupy small portions of a user's natural FOV, thus resulting in small display FOVs. Furthermore, the eye to screen distance for a smart phone or an ultra-mobile PC can change depending on how the user holds the device, which may result in a further reduction in display FOV. Given these changes in display FOV, the same target size/width (W), target distance/amplitude (D) and control display gain in pixels or millimeter measurement could be perceived as significantly different, and this difference may influence pointing task performance. A similar effect would also occur when using head-mounted displays with different FOV optical systems. Motivated by this, we decided to investigate whether a smaller display FOV has a significant effect on user performance when completing basic pointing tasks. If this supposition is true, the added difficulty from smaller display FOV may affect the applicability of Fitts’ law which is only modeled by the index of difficulty (ID) computed as a function of W and D. Specifically, if Fitts' law, commonly used to evaluate pointing tasks, is not suitable under restricted display FOV conditions, then an appropriate update of Fitts' law would help user experience designers to better understand and model the added difficulty when using restricted FOV devices such as ultra-mobile PCs, smart phones and head-mounted displays. In this paper we use both discrete and serial Fitts’ pointing tasks to understand the detailed quantitative relationship ... ... middle of paper ... ... of proportionally scaled W and D and across the three display sizes (6 × 8, 12 × 16 and 18 × 24 cm), that the smallest display size yielded significantly longer MT and a higher error rate. However, to our knowledge, the detailed relationship between display size (display FOV) and pointing task performance is still not fully known. Works Cited Taveira, A.D., & Choi, S.D. (2009). Review Study of Computer Input Devices and Older Users. International Journal of Human-Computer Interaction, 25(5), 455-474. Weaver W., & Shannon C.E. (1959). The mathematical theory of communication. University of Illinois Press Urbana. Zhai S. (2004). Characterizing computer input with Fitts’ law parameters–the information and non-information aspects of pointing. International Journal of Human-Computer Studies, 61(6), 791–809. Zuckerman J. (1954). Perimetry. Lippincott, Philadelphia.

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