虚拟学习环境下图形加工的认知负荷研究

Research on Cognitive Load of Graphic Processing in Virtual Reality Learning Environment

基于单探测变化觉察和双任务范式,采用项目数量(3)×呈现时间(2)×文字线索(2)混合实验设计,对沉浸式虚拟学习环境图形加工特征和认知负荷进行探讨,以任务绩效法与主观测量法评定认知负荷。44名大学生的实验结果显示:(1)项目数量对虚拟空间图形识记主任务绩效和主观认知负荷有显著影响,项目数量越多,主任务正确率越低,反应时越长,主观评定认知负荷越高,同时加工刺激数量以4个为宜;(2)呈现时间对虚拟空间图形识记次任务绩效有显著影响,呈现时间越长,次任务正确率越高,呈现时间超过0.5s有利于次任务加工;(3)文字线索对虚拟图形识记认知负荷有显著影响,重复性文字线索会增加认知负荷。结果表明,在沉浸式虚拟环境中,图形加工的认知负荷特点与平面和三维图形基本一致,项目数量多、呈现时间短以及有重复性文字线索时,认知负荷更高;任务绩效和主观测量评定指标在反映认知负荷强度上不完全一致。

To detect influential factors of cognitive load in virtual reality learning environment,this study selected44 undergraduates as subjects to conduct a three-factor mixed design experiment:3(memorization project number:3,4,5)x 2(presentation time:0.5 s,0.8 s)x 2(text clues:with or without),using single stimulus test paradigm for stimulus perception detection and dual-task paradigm for cognitive load measurement.Participants were asked to determine whether a figure had just appeared on certain position or not after learning.A sub-task signal appeared half the time.The results showed that:(1)The number of items has a significant impact on learners’cognitive load.The more items,the lower the correct rate of main task and the higher the learners’cognitive load was.The appropriate number of stimulus is four;(2)Item duration had a significant impact on learners’cognitive load.The longer the item duration,the higher the accuracy of sub-tasks and the lower the learners’cognitive load was.However,item duration didn’t affect main-task’s performance.Item duration longer than 0.5 s was helpful for sub-task processing;(3)Text cues had significant effect on cognitive load.Repeated text cues increased cognitive load.These findings illustrated that number of items and length of item duration was positively related to cognitive load;text clue was helpful to released subjective cognitive load.Task performance and subjective measurement indicators were not always consistent in reflecting cognitive load intensity.