Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of the RWTH Aachen, Neuenhofer Weg 21, 52074 Aachen, Germany.
Neuropsychologia. 2012 Jul;50(8):1844-51. doi: 10.1016/j.neuropsychologia.2012.04.010. Epub 2012 May 1.
The mental-rotation task is a well known research paradigm to examine cognitive processes of mental imaging and mental manipulation (Shepard & Metzler, 1971). So far, research has been focused on stimulus orientation which indicates the necessary amount of mental rotation. But little attention has been paid to stimulus parity, specifically if and how identical and mirror-reversed stimuli are processed differently. We wanted to fill this gap by combining performance, eye-tracking, and neurofunctional measures using pairwise presented three-dimensional Shepard-Metzler stimuli in a self-paced event-related fMRI design. Based on our results we tried to reason at which stage of the mental-rotation process the treatment of mirrored and identical stimuli begins to diverge. As a common finding, response times for tasks with mirrored stimuli were longer compared to tasks with identical stimuli reflecting their higher cognitive demand. Moreover, we observed smaller saccade amplitudes for mirrored than for identical stimuli suggesting a smaller functional field of view during stimulus perception. The eye-movement results were complemented by our neurofunctional findings. Here, the processing of mirrored stimuli led to less activation in parts of the early visual cortex that respond to the visual periphery than the processing of identical figures. This activation difference remained after eye-movement-associated activations had been excluded. We explain our findings by stimulus-parity-induced differences in saliency maps built up to enhance perception. Thus, the treatment of mirrored and identical stimuli begins to diverge very early in the mental-rotation process and is associated with differences in visual processing.
心理旋转任务是一种用于检验心理意象和心理操作认知过程的知名研究范式（Shepard & Metzler，1971）。到目前为止，研究一直集中在刺激方向上，该方向指示了心理旋转的必要量。但是，很少关注刺激的对等性，特别是是否以及如何以不同的方式处理相同和镜像反转的刺激。我们希望通过在自我调节的事件相关 fMRI 设计中使用成对呈现的三维 Shepard-Metzler 刺激，结合表现，眼动追踪和神经功能测量来填补这一空白。基于我们的结果，我们试图推理在心理旋转过程的哪个阶段开始出现对镜像和相同刺激的处理差异。作为一个常见的发现，与镜像刺激相比，具有相同刺激的任务的反应时间更长，这反映了它们更高的认知需求。此外，我们观察到镜像刺激的眼跳幅度小于相同刺激的眼跳幅度，这表明在刺激感知过程中功能视野较小。眼动结果得到了我们神经功能发现的补充。在这里，与处理相同的图形相比，处理镜像刺激会导致早期视觉皮层中对视觉外围做出反应的部分的激活减少。在排除了与眼动相关的激活之后，仍然存在这种激活差异。我们通过建立增强感知的显着性图中的刺激对等性诱导差异来解释我们的发现。因此，镜像和相同刺激的处理在心理旋转过程的早期就开始出现差异，并且与视觉处理的差异有关。
