Blur Effects on User Performance in Target-Pointing Tasks

TL;DR

This study investigates how display blur affects user performance in pointing tasks, revealing that increased blur raises movement time and errors, and proposing a model to predict these effects for adaptive interface design.

Contribution

It introduces a model that accurately estimates movement time under blur conditions and demonstrates how adjusting target size can mitigate blur effects.

Findings

Movement time and error rate increase with blur strength.

A model improves on Fitts' law to predict movement time under blur.

Adjusting target size reduces blur's impact on performance.

Abstract

In projectors and head-mounted displays, an out-of-focus image appears blurred. Even when a display itself is in focus, computer operation may be hindered if the display is far from the user or if a user has poor visual acuity, because the user cannot see the screen clearly. In this study, we conducted an experiment in which participants performed a pointing task under blurred display conditions and investigated the relationship between blur strength and user performance. The results showed that movement time and error rate increased as blur became stronger, and that the effect of blur on movement time was larger when targets were smaller. We further showed that movement time can be estimated with high accuracy by a model that improves on Fitts' law. In a follow-up experiment to examine the applicability of this model, we adjusted target size for each participant and showed that the effect of blur level on movement time could be reduced. These findings suggest potential use in tools that adapt user interfaces to users' visual acuity.