Ludwig Maximilian University, Munich, Germany.
Neuropsychologia. 2010 Sep;48(11):3365-70. doi: 10.1016/j.neuropsychologia.2010.07.005. Epub 2010 Jul 13.
Electrophysiological measurements were taken from observers performing a visual search within a single feature dimension, and between multiple dimensions. The N2pc to selected singleton target stimuli (rightward tilted lines) was increased when targets varied between feature dimensions, compared to the N2pc to the same rightward tilted line targets, in a condition in which targets varied only between feature values within the same dimension. The anterior and posterior N2 were not reliably modulated, but P3(b) amplitude was higher for singleton present trials that varied between dimensions than for those that varied within. The ERP elicited by singleton absent trials showed reduced P3 amplitude in the between-dimension condition. The electrophysiological modulations were accompanied by increased reaction times in the between-dimension condition, on both singleton present and absent trials. The results suggested that visual target detection is affected by early dimension-specific weighting of the current attentional task set. Furthermore, exhaustively searching multiple feature dimensions to determine the absence of a target incurs dimensional switching costs, possibly at a later stage.
对在单一特征维度内和多个维度之间执行视觉搜索的观察者进行了电生理测量。与在仅在同一维度内的特征值之间变化的条件下，当目标在特征维度之间变化时，对所选单一目标刺激（向右倾斜的线）的 N2pc 增加，而对相同向右倾斜的线目标的 N2pc 则增加。前部和后部 N2 没有可靠地调制，但对于在维度之间变化的单一存在试验，P3(b) 幅度高于在维度内变化的单一存在试验。在维度之间的条件下，对单一不存在试验的 ERP 显示 P3 幅度降低。在维度之间的条件下，无论是单一存在还是不存在试验，电生理调制都伴随着反应时间的增加。结果表明，视觉目标检测受到当前注意任务集的早期特定维度加权的影响。此外，为了确定目标不存在，详尽地搜索多个特征维度会导致维度切换成本，可能在稍后的阶段。
