Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom ; Institute of Child Health, University College London, London, United Kingdom.
PLoS One. 2013 Jun 11;8(6):e65601. doi: 10.1371/journal.pone.0065601. Print 2013.
A popular model of visual perception states that coarse information (carried by low spatial frequencies) along the dorsal stream is rapidly transmitted to prefrontal and medial temporal areas, activating contextual information from memory, which can in turn constrain detailed input carried by high spatial frequencies arriving at a slower rate along the ventral visual stream, thus facilitating the processing of ambiguous visual stimuli. We were interested in testing whether this model contributes to memory-guided orienting of attention. In particular, we asked whether global, low-spatial frequency (LSF) inputs play a dominant role in triggering contextual memories in order to facilitate the processing of the upcoming target stimulus. We explored this question over four experiments. The first experiment replicated the LSF advantage reported in perceptual discrimination tasks by showing that participants were faster and more accurate at matching a low spatial frequency version of a scene, compared to a high spatial frequency version, to its original counterpart in a forced-choice task. The subsequent three experiments tested the relative contributions of low versus high spatial frequencies during memory-guided covert spatial attention orienting tasks. Replicating the effects of memory-guided attention, pre-exposure to scenes associated with specific spatial memories for target locations (memory cues) led to higher perceptual discrimination and faster response times to identify targets embedded in the scenes. However, either high or low spatial frequency cues were equally effective; LSF signals did not selectively or preferentially contribute to the memory-driven attention benefits to performance. Our results challenge a generalized model that LSFs activate contextual memories, which in turn bias attention and facilitate perception.
一种流行的视觉感知模型表明，粗信息（由低空间频率携带）沿背侧流快速传输到前额叶和内侧颞叶区域，激活来自记忆的上下文信息，这反过来又可以约束沿腹侧视觉流以较慢速度到达的高空间频率的详细输入，从而促进对模棱两可的视觉刺激的处理。我们有兴趣测试这个模型是否有助于记忆引导注意力的定向。特别是，我们询问全局、低空间频率 (LSF) 输入是否在触发上下文记忆中起主导作用，以促进即将到来的目标刺激的处理。我们通过四个实验探索了这个问题。第一个实验通过显示与高空间频率版本相比，参与者在强制选择任务中更快、更准确地将场景的低空间频率版本与原始场景版本相匹配，从而复制了在感知辨别任务中报告的 LSF 优势。随后的三个实验测试了在记忆引导的隐蔽空间注意力定向任务中低空间频率与高空间频率的相对贡献。记忆引导注意力的影响得到了复制，预先暴露于与目标位置特定空间记忆相关的场景（记忆线索）会导致更高的感知辨别能力和更快的反应时间来识别场景中嵌入的目标。然而，高空间频率或低空间频率线索同样有效；LSF 信号并没有选择性或优先地为记忆驱动的注意力对性能的影响做出贡献。我们的结果挑战了一种普遍的模型，即 LSF 激活上下文记忆，而上下文记忆又偏向注意力并促进感知。
