School of Psychological Sciences, Tel Aviv University, Tel-Aviv, Israel.
Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel.
PLoS One. 2018 Jun 22;13(6):e0198242. doi: 10.1371/journal.pone.0198242. eCollection 2018.
During visual exploration or free-view, gaze positioning is largely determined by the tendency to maximize visual saliency: more salient locations are more likely to be fixated. However, when visual input is completely irrelevant for performance, such as with non-visual tasks, this saliency maximization strategy may be less advantageous and potentially even disruptive for task-performance. Here, we examined whether visual saliency remains a strong driving force in determining gaze positions even in non-visual tasks. We tested three alternative hypotheses: a) That saliency is disadvantageous for non-visual tasks and therefore gaze would tend to shift away from it and towards non-salient locations; b) That saliency is irrelevant during non-visual tasks and therefore gaze would not be directed towards it but also not away-from it; c) That saliency maximization is a strong behavioral drive that would prevail even during non-visual tasks.
Gaze position was monitored as participants performed visual or non-visual tasks while they were presented with complex or simple images. The effect of attentional demands was examined by comparing an easy non-visual task with a more difficult one.
Exploratory behavior was evident, regardless of task difficulty, even when the task was non-visual and the visual input was entirely irrelevant. The observed exploratory behaviors included a strong tendency to fixate salient locations, central fixation bias and a gradual reduction in saliency for later fixations. These exploratory behaviors were spatially similar to those of an explicit visual exploration task but they were, nevertheless, attenuated. Temporal differences were also found: in the non-visual task there were longer fixations and later first fixations than in the visual task, reflecting slower visual sampling in this task.
We conclude that in the presence of a rich visual environment, visual exploration is evident even when there is no explicit instruction to explore. Compared to visually motivated tasks, exploration in non-visual tasks follows similar selection mechanisms, but occurs at a lower rate. This is consistent with the view that the non-visual task is the equivalent of a dual-task: it combines the instructed task with an uninstructed, perhaps even mandatory, exploratory behavior.
在视觉探索或自由观察期间，注视定位在很大程度上取决于最大化视觉显著性的趋势：更显著的位置更有可能被注视。然而，当视觉输入与表现完全无关时，例如在非视觉任务中，这种显著性最大化策略可能不太有利，甚至对任务表现产生干扰。在这里，我们研究了即使在非视觉任务中，视觉显著性是否仍然是决定注视位置的强大驱动力。我们检验了三个替代假设：a）显著性对非视觉任务不利，因此注视将倾向于远离它并转移到非显著位置；b）显著性在非视觉任务中无关紧要，因此注视不会指向它，也不会远离它；c）显著性最大化是一种强大的行为驱动力，即使在非视觉任务中也会占主导地位。
当参与者在进行视觉或非视觉任务时，监测他们的注视位置，同时呈现复杂或简单的图像。通过比较简单和困难的非视觉任务，检验了注意力需求的影响。
无论任务难度如何，即使任务是视觉上无关的，视觉输入完全无关紧要，探索性行为仍然很明显。观察到的探索性行为包括强烈注视显著位置的趋势、中央注视偏差和随后注视的显著性逐渐降低。这些探索性行为在空间上与明确的视觉探索任务相似，但它们被削弱了。还发现了时间差异：在非视觉任务中，注视时间更长，首次注视时间更晚，这反映了在该任务中视觉采样较慢。
我们得出的结论是，在存在丰富视觉环境的情况下，即使没有明确的探索指令，也会出现视觉探索。与视觉驱动任务相比，非视觉任务中的探索遵循类似的选择机制，但发生的频率较低。这与非视觉任务相当于双重任务的观点一致：它将指令任务与未指令的、可能甚至是强制性的探索行为结合起来。
