Task-irrelevant visual perceptual learning in children and adults

Task-irrelevant visual perceptual learning (VPL) was examined in a group of elementary school age children (7 – 10 years old, n = 20 subjects) and a group of young adults (18 – 31 years old, n = 20 subjects). The experiment consisted of several sessions conducted on separate days. In the first session subjects’ thresholds for coherent motion detection were measured. In the second session subjects completed a pretest for discrimination performance of different coherent motion directions. From the third to the fourteenth session subjects performed a rapid serial visual presentation (RSVP) task at screen center while coherent motion in different directions was exposed as task-irrelevant in the visual periphery. Prior to the experiment each subject was randomly assigned to two different exposure conditions (n = 10 subjects for each age group for each exposure condition). There was a threshold exposure condition in which coherent motion was exposed at the individual threshold for coherent motion detection. There was also a suprathreshold exposure condition in which coherent motion was exposed at 4.0 x individual threshold for coherent motion detection. In each trial of the RSVP one coherent motion direction, termed the “task-irrelevant learning direction” was exclusively paired with RSVP targets, while other coherent motion directions were randomly paired with RSVP distractors (“untrained directions”). Finally, in the fifteenth session subjects completed a posttest in motion direction discrimination exactly as in the pretest. The results show that subjects in both age groups improved significantly on the RSVP over the course of the exposure sessions. In the threshold exposure condition subjects in each age group significantly improved discrimination performance for the task-irrelevant learning direction from pretest to posttest. In the suprathreshold exposure condition children significantly improved discrimination performance for the task-irrelevant learning direction from pretest to posttest, while young adults significantly decreased discrimination performance. Furthermore, subjects also completed the Useful Field of View (UFOV) subtests for processing speed, divided attention and selective attention. The discrimination performance increase in the suprathreshold exposure condition in children was significantly correlated with the selective attention ability, such that children with greater discrimination performance increase from pretest to posttest also tended to show greater selective attention ability. No such association was observed either for young adults or for any other UFOV subtest.

本研究针对两组被试开展任务无关视觉知觉学习（Task-irrelevant visual perceptual learning, VPL）的相关实验：一组为小学年龄段儿童（7~10岁，n=20名被试），另一组为青年成年人（18~31岁，n=20名被试）。实验由多日开展的多个阶段组成：第一阶段测量被试的相干运动检测阈值；第二阶段完成不同相干运动方向辨别表现的预测试；第三至第十四阶段中，被试在屏幕中央完成快速序列视觉呈现（rapid serial visual presentation, RSVP）任务，同时在视觉外周呈现不同方向的相干运动，作为任务无关刺激。实验前，每名被试被随机分配至两种暴露条件之一（每个年龄组的每种暴露条件下均有10名被试）：其一为阈值暴露条件，即相干运动的呈现强度为个体相干运动检测阈值；其二为超阈值暴露条件，即相干运动的呈现强度为个体相干运动检测阈值的4.0倍。在RSVP任务的每一试次中，某一特定相干运动方向被称为“任务无关学习方向”，仅与RSVP靶刺激配对，其余相干运动方向则随机与RSVP分心刺激配对，即“未训练方向”。第十五阶段为后测试，被试完成与预测试完全一致的运动方向辨别任务。实验结果显示：两个年龄组的被试在暴露阶段的RSVP任务表现均有显著提升。在阈值暴露条件下，两个年龄组的被试在预测试至后测试中，任务无关学习方向的辨别表现均有显著改善。在超阈值暴露条件下，儿童的任务无关学习方向辨别表现从预测试到后测试有显著提升，而青年成年人的该类辨别表现则显著下降。此外，所有被试均完成了有效视野（Useful Field of View, UFOV）的子测试，包括加工速度、分配性注意和选择性注意。儿童在超阈值暴露条件下的辨别表现提升量，与选择性注意能力显著相关：即预测试至后测试中辨别表现提升幅度更大的儿童，其选择性注意能力也更强。而在青年成年人组或其他UFOV子测试中，均未观察到此类关联。