Pegna Alan J, Darque Alexandra, Roberts Mark V, Leek E Charles
1 Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland.
2 School of Psychology, University of Queensland, St Lucia, QLD, Australia.
Q J Exp Psychol (Hove). 2018 Jun;71(6):1419-1430. doi: 10.1080/17470218.2017.1333129. Epub 2018 Jan 1.
This study investigates the effects of stereo disparity on the perception of three-dimensional (3D) object shape. We tested the hypothesis that stereo input modulates the brain activity related to perceptual analyses of 3D shape configuration during image classification. High-density (256-channel) electroencephalogram (EEG) was used to record the temporal dynamics of visual shape processing under conditions of two-dimensional (2D) and 3D visual presentation. On each trial, observers made image classification judgements ('Same'/'Different') to two briefly presented, multi-part, novel objects. On different-object trials, stimuli could either share volumetric parts but not the global 3D shape configuration and have different parts but the same global 3D shape configuration or differ on both aspects. Analyses using mass univariate contrasts showed that the earliest sensitivity to 2D versus 3D viewing appeared as a negative deflection over posterior locations on the N1 component between 160 and 220 ms post-stimulus onset. Subsequently, event-related potential (ERP) modulations during the N2 time window between 240 and 370 ms were linked to image classification. N2 activity reflected two distinct components - an early N2 (240-290 ms) and a late N2 (290-370 ms) - that showed different patterns of responses to 2D and 3D input and differential sensitivity to 3D object structure. The results revealed that stereo input modulates the neural correlates of 3D object shape. We suggest that this reflects differential perceptual processing of object shape under conditions of stereo or mono input. These findings challenge current theories that attribute no functional role for stereo input during 3D shape perception.
本研究调查了立体视差对三维（3D）物体形状感知的影响。我们测试了这样一个假设，即在图像分类过程中，立体视觉输入会调节与3D形状配置的感知分析相关的大脑活动。使用高密度（256通道）脑电图（EEG）来记录二维（2D）和3D视觉呈现条件下视觉形状处理的时间动态。在每次试验中，观察者对两个短暂呈现的、多部分的、新颖物体进行图像分类判断（“相同”/“不同”）。在不同物体试验中，刺激要么共享体积部分但不共享全局3D形状配置，要么具有不同部分但全局3D形状配置相同，要么在这两个方面都不同。使用大量单变量对比分析表明，对2D与3D观看的最早敏感性表现为刺激开始后160至220毫秒之间N1成分后部位的负向偏转。随后，在240至370毫秒之间的N2时间窗口内的事件相关电位（ERP）调制与图像分类相关。N2活动反映了两个不同的成分——早期N2（240 - 290毫秒）和晚期N2（290 - 370毫秒）——它们对2D和3D输入表现出不同的反应模式，并且对3D物体结构具有不同的敏感性。结果表明，立体视觉输入调节了3D物体形状的神经关联。我们认为，这反映了在立体或单眼输入条件下对物体形状的不同感知处理。这些发现挑战了当前认为立体视觉输入在3D形状感知中没有功能作用的理论。
