Date Published: March 14, 2019
Publisher: Public Library of Science
Author(s): Fion Choi Hung Lee, Siu Shing Man, Alan Hoi Shou Chan, Markus Lappe.
Image magnification often results in disorientation through loss of orientation and location during inspection. This study investigated the effects of three different magnification modes viz. full screen, circular, and fixed-area on visual inspection performance. Also, to improve participants’ global orientation with respect to the original product, location cues in the form of halftone landmarks were introduced as a job aid and their effectiveness on inspection performance was examined. Twenty-eight undergraduates participated in the experiment. Significant magnification mode effect was found, but the location cue effect was found non-significant. The results suggested that the presentation of content/contextual information on one single screen should be considered together with the nature of the visual task and participants’ search behaviors, and that the aid of location cues might be useful when the visual task demanded a high level of search memory and/or an unsystematic search strategy was employed by inspectors.
Visual inspection is one of the quality control processes in manufacturing industry and plays an important role in our daily live [1–4]. Previous studies have focused on obtaining an in-depth understanding of and improving human visual related task performance from a diversity of perspectives. For instance, Yu and Yang  conducted a study to examine the age-related changes in visual lobe shape characteristics and its relationships to visual search performance. Liu and Yu  used an eye-tracking technique to investigate the influence of social presence on eye movements in visual search tasks and found that the presence of an audience could evoke a social facilitation effect on response time in visual search tasks. Wahn, Schwandt  found that the performance of joint visual search can be improved by employing a tactile or an auditory display to exchange gaze information about the search partner.
Three interface factors of magnification mode, location cue, and magnification power were examined in this study. The results indicated a significant magnification mode effect on inspection speed, accuracy, and overall TLX score. However, the usefulness of location cues was not clearly seen as indicated by the non-significant difference in speed, accuracy, and user perception between the cued and non-cued conditions.
This study showed a significant magnification mode effect and a non-significant location cue effect on visual inspection performance. It reveals that a proper selection of magnification mode is prominent to visual task performance. It is because participants’ search strategies were found varied in the full screen, circular, and fixed-area modes of magnification, and thus the inspection performance in different modes were different. In this experiment, the full screen mode was found to outperform the circular and fixed-area modes. Two reasons were suggested: the use of systematic search strategy by participants in the full screen mode and the unimportance of contextual information to the current visual inspection task.