Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy.
PLoS One. 2011 Feb 28;6(2):e17453. doi: 10.1371/journal.pone.0017453.
The ability to process concurrently multiple visual objects is fundamental for a coherent perception of the world. A core component of this ability is the simultaneous individuation of multiple objects. Many studies have addressed the mechanism of object individuation but it remains unknown whether the visual system mandatorily individuates all relevant elements in the visual field, or whether object indexing depends on task demands. We used a neural measure of visual selection, the N2pc component, to evaluate the flexibility of multiple object individuation. In three ERP experiments, participants saw a variable number of target elements among homogenous distracters and performed either an enumeration task (Experiment 1) or a detection task, reporting whether at least one (Experiment 2) or a specified number of target elements (Experiment 3) was present. While in the enumeration task the N2pc response increased as a function of the number of targets, no such modulation was found in Experiment 2, indicating that individuation of multiple targets is not mandatory. However, a modulation of the N2pc similar to the enumeration task was visible in Experiment 3, further highlighting that object individuation is a flexible mechanism that binds indexes to object properties and locations as needed for further object processing.
同时处理多个视觉对象的能力是连贯感知世界的基础。这种能力的核心组成部分是同时对多个对象进行个体化。许多研究都探讨了对象个体化的机制，但仍不清楚视觉系统是否强制性地对视野中的所有相关元素进行个体化，或者对象索引是否取决于任务需求。我们使用视觉选择的神经测量指标 N2pc 成分来评估多个对象个体化的灵活性。在三个 ERP 实验中，参与者在同质干扰物中看到了不同数量的目标元素，并执行了计数任务（实验 1）或检测任务，报告是否存在至少一个（实验 2）或指定数量的目标元素（实验 3）。虽然在计数任务中，N2pc 反应随着目标数量的增加而增加，但在实验 2 中没有发现这种调制，表明对多个目标的个体化不是强制性的。然而，在实验 3 中，类似于计数任务的 N2pc 调制是可见的，进一步强调了对象个体化是一种灵活的机制，它根据进一步的对象处理需要将索引绑定到对象属性和位置上。
