Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany.
BMC Neurosci. 2011 Jan 26;12:14. doi: 10.1186/1471-2202-12-14.
Visual perception is strongly determined by accumulated experience with the world, which has been shown for shape, color, and position perception, in the field of visuomotor learning, and in neural computation. In addition, visual perception is tuned to statistics of natural scenes. Such prior experience is modulated by neuronal top-down control the temporal properties of which had been subject to recent studies. Here, we deal with these temporal properties and address the question how early in time accumulated past experience can modulate visual perception.
We performed stimulus discrimination experiments and compared a group of Chinese participants with a German control group. The perception of our briefly presented visual objects (targets) was disturbed by masking stimuli which appeared in close spatiotemporal proximity. These masking stimuli were either intact or scrambled Chinese characters and did not overlap with the targets. In contrast to German controls, Chinese participants show substantial performance differences for real versus scrambled Chinese characters if these masking stimuli were presented as early as less than 100 milliseconds after the onset of the target. For Chinese observers, it even occured that meaningful masking stimuli enhanced target identification if they were shown at least 100 milliseconds after target onset while the same stimuli impaired recognition if presented in close temporal proximity to the target. The latter finding challenges interpretations of our data that solely rely on stimulus contours or geometric properties and emphasizes the impact of prior experience on the very early temporal dynamics of the visual system.
Our findings demonstrate that prior experience which had been accummulated long before the experiments can modulate the time course of perception intriguingly early, namely already immediately after the perceptual onset of a visual event. This modulation cannot solely operate as a feedback in response to the visual event but is rather a permanent effect.
视觉感知受到与世界互动的经验的强烈影响，这在视动学习领域以及神经计算中已经得到了证实，体现在形状、颜色和位置感知上。此外，视觉感知还适应于自然场景的统计数据。这种先验经验受到神经元自上而下控制的调节，其时间特性是最近研究的主题。在这里，我们研究这些时间特性，并解决了一个问题，即积累的过去经验能在多早的时间内调节视觉感知。
我们进行了刺激辨别实验，并将中国参与者与德国对照组进行了比较。我们短暂呈现的视觉对象（目标）的感知受到出现在时空接近的掩蔽刺激的干扰。这些掩蔽刺激是完整的或打乱的汉字，与目标不重叠。与德国对照组相比，如果掩蔽刺激在目标出现后不到 100 毫秒就出现，中国参与者对真实汉字和打乱汉字的感知会有明显的差异。对于中国观察者来说，如果掩蔽刺激在目标出现至少 100 毫秒后出现，那么有意义的掩蔽刺激会增强目标识别；而如果掩蔽刺激在与目标非常接近的时间出现，则会损害识别。后一种发现挑战了仅依赖于刺激轮廓或几何属性的对我们数据的解释，并强调了先验经验对视觉系统早期时间动态的影响。
我们的发现表明，在实验之前很久就积累的先验经验可以令人惊讶地早地调节感知的时间进程，即在视觉事件的感知开始后立即进行调节。这种调节不能仅仅作为对视觉事件的反馈来运作，而是一种永久的影响。
