Siman-Tov Ziv, Lev Maria, Polat Uri
School of Optometry and Vision Sciences, Bar-Ilan University, Ramat Gan, Israel.
J Vis. 2025 Jun 2;25(7):5. doi: 10.1167/jov.25.7.5.
The perception of chromatic and achromatic visual information is combined and processed in the parvocellular stream; however, they are separate processes at the early stage of the visual cortex. In our previous study, we noted that there is difficulty discriminating the color of a letter target presented at the fovea under a crowded presentation for a short time. Visual crowding occurs when an easily identified isolated stimulus becomes very difficult to identify when it is surrounded by stimuli with similar properties. One opinion is that crowding reduces the ability to identify the target but not its features (e.g., color and texture); however, some studies indicated that the ability to recognize features is also impaired under peripheral crowding conditions. Here, we investigated whether the processing of chromatic information can be impaired at the fovea using a classic crowding experiment when tested at brief presentation times (20, 40, and 120 ms). The participants reported both the target's identity and chromaticity (dual task). We found that the target's identification and color discrimination are impaired when presented for 20-40 ms but that they recover for longer presentation times. This effect is increased when temporal backward masking is added. This finding suggests that crowding resembles masking under brief presentation times and occurs at a later processing stage, after an initial masking stage.
彩色和非彩色视觉信息的感知在小细胞通路中进行整合和处理；然而，在视觉皮层的早期阶段，它们是分开的过程。在我们之前的研究中，我们注意到在短时间的拥挤呈现条件下，很难辨别出中央凹处呈现的字母目标的颜色。当一个易于识别的孤立刺激被具有相似属性的刺激包围时，就会发生视觉拥挤，此时该孤立刺激变得很难识别。一种观点认为，拥挤会降低识别目标的能力，但不会影响其特征（如颜色和纹理）；然而，一些研究表明，在外周拥挤条件下，识别特征的能力也会受损。在这里，我们使用经典的拥挤实验，研究了在短暂呈现时间（20、40和120毫秒）进行测试时，中央凹处的彩色信息处理是否会受到损害。参与者报告目标的身份和色度（双重任务）。我们发现，当呈现20 - 40毫秒时，目标的识别和颜色辨别会受损，但在较长呈现时间时会恢复。当添加时间逆向掩蔽时，这种效应会增强。这一发现表明，在短暂呈现时间下，拥挤类似于掩蔽，并且发生在初始掩蔽阶段之后的后期处理阶段。
