关键词: 预期, 突显干扰项, 注意捕获, 任务负载, 刺激环境

Abstract: Pursuing relevant objects and avoiding irrelevant ones are fundamental functions of attention. Attention can efficiently be directed toward relevant objects when they have foreknowledge of target-defining features, such as color, orientation, and location. The interference of the distractors could increase when participants are instructed to ignore distractors, which is the attentional “white bear” effect. According to the biased competition theory, objects that match active representations in working memory gain a competitive advantage. Thus, salient distractors matched with working memory representations would capture more attention. The environment variability and expectation of salient distractors influence the activation intensity of representations in working memory. However, the effects of variability to the environment on attentional capture are inconsistent when salient distractors could be expected. These discrepancies may arise from whether the expectation is derived from the external environment or internal memory.
This study employed a traditional additional singleton paradigm to explore the influence of the environment variability and expectation of salient distractors on attentional capture. Participants were required to search a circle among seven squares and then indicate the orientation of the line in the circle. One circle and seven squares were drawn in red or green, and one of the squares as a salient distractor had a different color than the remaining items. In the constant environment condition, the colors of targets and salient distractors were fixed, while in the variable environment condition, the colors of targets and salient distractors were swapped randomly from trial to trial. In experiments 1 and 2, we investigated whether the effects of expectation of external and internal cue-guided salient distractor on attentional capture were influenced by the environment variability, respectively. In the predictable condition, it was the external cue-guided salient distractor when participants knew that the salient distractor would appear on each trial and never be the target during the search task. In contrast, it was the internal cue-guided salient distractor when participants were explicitly informed that the location of a salient distractor would change clockwise in subsequent trials, so that they could predict the location of a salient distractor. In experiment 3, we investigated whether the effect of the predictable internal cue-guided salient distractor on attentional capture was influenced by task load in the constant environment condition. Participants performed a verbal concurrent task during the search task. In the verbal concurrent task, they were required to count backward verbally in decrements of three from a two-digit number (i.e., the high task load condition), and repeatedly articulate a two-digit number (i.e., the low task load condition). To compare the impact of task load on attentional capture in the constant environment, we calculated the load cost as the difference between high and low task load conditions.
The results showed that salient distractors captured attention in both predictable external and internal cue-guided salient distractor conditions. In the predictable condition, the response time was longer in the variable environment condition than in the constant environment condition when salient distractors were guided by external cues. But the response time was not significantly different between the variable and constant environment conditions when salient distractors were guided by internal cues. However, the load cost was larger in the predictable condition compared to the unpredictable condition when salient distractors were guided by internal cue. Taken together, the findings suggest that various environments lead to greater attentional capture when external cue-guided salient distractors are predictable, and high task load leads to greater attentional capture when internal cue-guided salient distractors are predictable. The current study provides a reasonable explanation for the inconsistency of how expected salient distractors capture attention is influenced by the environment variability.

Key words: expectation, salient distractor, attentional capture, task load, environment