University of British Columbia, Vancouver, BC, Canada.
Cogn Neuropsychol. 2009 Jul;26(5):456-70. doi: 10.1080/02643290903444582.
We investigated the perceptual time course of global/local processing using event-related potentials (ERPs). Participants discriminated the global or local level of hierarchical letters of different sizes and densities. Participants were faster to discriminate the local level of large/sparse letters and the global level of small/dense letters. This was mirrored in early ERP components: The N1/N2 had smaller peak amplitudes when participants made discriminations at the level that took precedence. Only global discriminations for large/sparse letters led to amplitude enhancement of the later P3 component, suggesting that additional attention-demanding processes are involved in discriminating the global level of these stimuli. Our findings suggest a dual-locus time course for global/local processing: (a) Level precedence occurs early in visual processing; (b) extra processing is required at a later stage, but only for global discriminations of large, sparse, stimuli, which may require additional attentional resources for active grouping.
我们使用事件相关电位（ERPs）研究了全局/局部加工的知觉时间进程。参与者辨别了不同大小和密度的分层字母的全局或局部水平。参与者更快地辨别了大/稀疏字母的局部水平和小/密集字母的全局水平。这在早期的 ERP 成分中得到了反映：当参与者在优先的水平上进行辨别时，N1/N2 的峰值幅度较小。只有对大/稀疏字母的全局辨别导致后期 P3 成分的振幅增强，这表明在辨别这些刺激的全局水平时涉及到额外的需要注意力的处理过程。我们的研究结果表明全局/局部处理的双焦点时间进程：（a）水平优先发生在视觉处理的早期；（b）在稍后的阶段需要额外的处理，但仅适用于大、稀疏刺激的全局辨别，这可能需要额外的注意力资源来进行主动分组。
