Brook-Carter N, Stevens A, Reed N, Thompson S
TRL, Crowthorne House, Nine Mile Ride, Wokingham, Berkshire, UK.
Ergonomics. 2009 Feb;52(2):177-86. doi: 10.1080/00140130701768471.
Occlusion is a practical technique to measure the visual demand imposed by in-vehicle tasks and to assess whether a task can be resumed having been interrupted. This study describes a number of important factors and variables that need to be controlled to ensure reliability of results. Training of participants on in-vehicle tasks is found to help consistency and five training sessions are required for complex tasks. No significant differences in training with and without occlusion goggles are reported. The required sample size is dependent on the variability of the task; for those investigated an appropriate sample size is found to be 14. For in-vehicle systems that exhibit a delay in response to the user, consistency is improved when these delays are excluded from timing measurements. In terms of calculating the occlusion parameter R, the within-participant basis is most consistent by taking the ratio of the respective median total shutter open time and total task times across trial repetitions completed by one participant on each task under evaluation and, for the purposes of identifying interface designs that exhibit poor resumability, the 85th percentile value is identified as most suitable. Findings from the study are discussed in terms of future application of the occlusion technique to assess in-vehicle information systems (IVIS).
遮挡法是一种实用技术，用于测量车内任务所产生的视觉需求，并评估一项任务在中断后能否恢复。本研究描述了一些为确保结果可靠性而需要控制的重要因素和变量。发现对参与者进行车内任务培训有助于提高一致性，复杂任务需要进行五次培训。报告称，使用和不使用遮挡护目镜进行培训没有显著差异。所需样本量取决于任务的变异性；对于所研究的任务，合适的样本量为14。对于对用户响应存在延迟的车内系统，在计时测量中排除这些延迟时，一致性会得到提高。在计算遮挡参数R时，通过计算一名参与者在每项评估任务的多次试验重复中各自的快门总开启时间中位数与总任务时间的比值，以参与者内部为基础最为一致，并且为了识别恢复性较差的界面设计，第85百分位数值被确定为最合适的。本研究结果将根据遮挡技术在评估车内信息系统（IVIS）方面的未来应用进行讨论。
