Eye typing interfaces enable a person to enter text into an interface using only their own eyes. But despite the inherent advantages of touchless operation and intuitive design, such eye-typing interfaces often suffer from slow typing speeds, resulting in slow words per minute (WPM) counts. In this study, we add word and letter prediction to the eye-typing interface and investigate users' typing performance as well as their subjective experience while using the interface. In experiment 1, we compared three typing interfaces with letter prediction (LP), letter+word prediction (L+WP), and no prediction (NoP), respectively. We found that the interface with L+WP achieved the highest average text entry speed (5.48 WPM), followed by the interface with LP (3.42 WPM), and the interface with NoP (3.39 WPM). Participants were able to quickly understand the procedural design for word prediction and perceived this function as very helpful. Compared to LP and NoP, participants needed more time to familiarize themselves with L+WP in order to reach a plateau regarding text entry speed. Experiment 2 explored training effects in L+WP interfaces. Two moving speeds were implemented: slow (6.4{\deg}/s same speed as in experiment 1) and fast (10{\deg}/s). The study employed a mixed experimental design, incorporating moving speeds as a between-subjects factor, to evaluate its influence on typing performance throughout 10 consecutive training sessions. The results showed that the typing speed reached 6.17 WPM for the slow group and 7.35 WPM for the fast group after practice. Overall, the two experiments show that adding letter and word prediction to eye-typing interfaces increases typing speeds. We also find that more extended training is required to achieve these high typing speeds.

翻译：眼动打字界面允许用户仅通过眼睛在界面中输入文本。尽管具有免触摸操作和直观设计的固有优势，但此类眼动打字界面常因打字速度缓慢而导致每分钟单词数（WPM）偏低。本研究为眼动打字界面添加了单词与字母预测功能，并探究了用户在界面使用过程中的打字性能及主观体验。实验1比较了三种打字界面：字母预测（LP）、字母+单词预测（L+WP）和无预测（NoP）。研究发现，L+WP界面实现了最高的平均文本输入速度（5.48 WPM），其次为LP界面（3.42 WPM）和NoP界面（3.39 WPM）。参与者能够快速理解单词预测的程序设计，并认为该功能非常实用。与LP和NoP相比，参与者需要更长时间熟悉L+WP才能达到文本输入速度的稳定期。实验2探究了L+WP界面中的训练效应，设置了慢速（6.4°/秒，与实验1相同）和快速（10°/秒）两种移动速度。研究采用混合实验设计，将移动速度作为被试间因素，评估其对10次连续训练中打字性能的影响。结果显示，练习后慢速组的打字速度达到6.17 WPM，快速组达到7.35 WPM。总体而言，两项实验表明，在眼动打字界面中添加字母与单词预测可提升打字速度，但需更长时间的训练才能实现这些高速打字表现。