PDF(Pubmed)
Abstract：
Online methods allow testing of larger, more diverse populations, with much less effort than in-lab testing. However, many psychophysical measurements, including visual crowding, require accurate eye fixation, which is classically achieved by testing only experienced observers who have learned to fixate reliably, or by using a gaze tracker to restrict testing to moments when fixation is accurate. Alas, both approaches are impractical online since online observers tend to be inexperienced, and online gaze tracking, using the built-in webcam, has a low precision (±4 deg, Papoutsaki et al., 2016). The EasyEyes open-source software reliably measures peripheral thresholds online with accurate fixation achieved in a novel way, without gaze tracking. EasyEyes tells observers to use the cursor to track a moving crosshair. At a random time during successful tracking, a brief target is presented in the periphery. The observer responds by identifying the target. To evaluate EasyEyes fixation accuracy and thresholds, we tested 12 naive observers in three ways in a counterbalanced order: first, in the lab, using gaze-contingent stimulus presentation (Kurzawski et al., 2023; Pelli et al., 2016); second, in the lab, using EasyEyes while independently monitoring gaze; third, online at home, using EasyEyes. We find that crowding thresholds are consistent (no significant differences in mean and variance of thresholds across ways) and individual differences are conserved. The small root mean square (RMS) fixation error (0.6 deg) during target presentation eliminates the need for gaze tracking. Thus, EasyEyes enables fixation-dependent measurements online, for easy testing of larger and more diverse populations.
摘要：
在线方法允许测试更大的，更多样化的人口，与实验室测试相比，工作量要少得多。然而,许多心理物理学测量，包括视觉拥挤，需要准确的眼睛固定，这通常是通过只测试有经验的观察者来实现的，他们已经学会了可靠地固定，或通过使用凝视跟踪器将测试限制在固定准确的时刻。唉,这两种方法在网上都是不切实际的，因为在线观察者往往缺乏经验，和在线凝视跟踪，使用内置的网络摄像头，精度较低(±4度，Papoutsaki等人。,2016)。EasyEyes开源软件可靠地在线测量外围阈值，以新颖的方式实现精确固定，没有凝视跟踪。EasyEyes告诉观察者使用光标来跟踪移动的十字准线。在成功跟踪期间的随机时间，在外围提出了一个简短的目标。观察者通过识别目标来响应。为了评估EasyEyes固定的准确性和阈值，我们以平衡的顺序以三种方式测试了12个幼稚的观察者：第一，在实验室里,使用凝视或有刺激呈现(Kurzawski等人。,2023年；佩里等人。,2016)；第二，在实验室里,使用EasyEyes，同时独立监测凝视；第三，在家上网,使用EasyEyes。我们发现拥挤阈值是一致的（不同方式的阈值的均值和方差没有显着差异），并且个体差异是保守的。在目标呈现期间的小的均方根(RMS)固定误差(0.6deg)消除了对注视跟踪的需要。因此，EasyEyes实现了依赖于固定的在线测量，便于对更大和更多样化的人群进行测试。
