Abstract: A large number of human actives depend greatly on visual–spatial processing in mental rotation and visual search specifically. The contribution of visual–spatial processing abilities to performance in science, mathematics, engineering, and technology is so important that it even controls other relevant skills, such as memory and mathematical reasoning. Importantly, visual–spatial skills are also malleable which respond effectively to learning interventions and life experiences. In order to reliably identify age-group differences on characteristic of eye movements and priority of feature processing in visual processing, we employed a more complex comparative visual search task. Whereas the general visual search task requires participants to maintain a representation of a single target, comparative visual search task requires participants to keep two sets of items in mind at the same time. By giving abundant information about visual behavior during a significant class of cognitive conditions, comparative visual research task provided more possibilities to formulate and test new visual-spatial processing. In the present study, experimental materials consisted of 72 trials, two halves of which (24, 30, or 36 items per half) contained visual primitives of various colors (blue, green, red) and shapes (triangles, circles, squares). Two targets next to fixation were presented; the targets on one-half of the trials were the same, and on the other half of the trials, the targets differed by shape, color, or shape and color. We conducted a 2 (age: old adult, young adult) × 3 (item: 12, 15,18) × 3 (target: shape, color, shape and color) experimental design. An EyeLink 2000 eye tracker was used to ensure accurate fixation of the designated fixation location prior to each stimulus presentation and to record the location and duration of fixations. Participants performed a conjunctive search to ascertain whether the two halves were identical both quickly and accurately, and they provided no instruction regarding the visual–spatial processing strategy they were to use. The results showed that the comparative search task produced age-group decrements in eye movement measures, including longer total fixation time, more fixation counts, longer average saccade amplitude and fixation time on target stimulus for the older adults when the display size (12, 15, or 18 items per half) increases. These influences of fixation on eye movements showed quite closely with the aging effects observed in standard visual search task, which supported older adults are more likely to experience a larger decline in retinal acuity than young adults in later life. Therefore, older adults required more time than younger adults to detect, search, memory and recognize visual targets. However, Response times were shorter for redundant trials than for color-only and shape-only trials for both old and young participants. Therefore, two groups of participants had similar priority of number of dimension and characteristic of feature attribute. Given the extant evidence of strengths for holistic visual processing in older adults, the results which showed cognitive aging for older adults and similar priority of feature attribute to young adults are significant because they suggest such strengths may be task dependent.

Key words: comparative search task, older adult, eye movement, cognitive aging

摘要： 本研究通过增加组成图片的图形数量和改变目标图形的特征，考察老年人和大学生在比较视觉搜索任务中的眼动特点和图形特征加工的优先性。结果表明与青年人相比，老年人在比较视觉搜索过程中总注视时间和注视次数增加，平均眼跳幅度减少，对目标刺激的注视时间增加。老年人和青年人在目标刺激的注视过程中都表现出图形维度数量的优先性，即表现为颜色和形状都不同的目标刺激注视时间最短，颜色不同和形状不同的目标刺激在注视时间上差异不显著。说明老年人在比较视觉搜索过程中存在认知老化,在图形特征加工的优先性上结果和青年人一致，以上结果与年龄和研究任务有关。

关键词: 比较视觉搜索任务, 老年人, 眼动, 认知老化