Orlov Tanya, Amit Daniel J, Yakovlev Volodya, Zohary Ehud, Hochstein Shaul
Hebrew University, Israel.
J Cogn Neurosci. 2006 Mar;18(3):399-417. doi: 10.1162/089892906775990660.
What mechanism underlies serial order memory? Studying preverbal serial memory shows that macaque monkeys reproducing a sequence of items can acquire knowledge of item ordinal position. In our previous experiment, macaques were repeatedly presented with image lists (first shown sequentially and then simultaneously on a touch screen together with a distractor chosen randomly from other lists). The task was to touch list images in the correct order. The monkeys' natural tendency was to categorize images by their ordinal position or number because their most common error was touching the distractor when it had the same ordinal number (in its own list) as the correct image. Item-to-item associations were used to complete the categorization strategy. Proposing a dynamic image-salience hypothesis for serial recall (based on category-to-image influence and a salience computation for identifying touch targets), we now study the category label characteristics in the context of this hypothesis. We found that these category labels are absolute, ordinal-number-based categories (first, second, etc.), not relative memorized as relative distance from the beginning and the end of the list, and not based on fixed ranking of reward contingency/image familiarity. Even isolated from item-item associations, the categories demonstrate category tuning (as well as the corresponding overlap of adjacent ordinal number codes). Moreover, monkeys choose images by proximity of their category to the current touch number, irrespective of the accuracy of the preceding choice. Category tuning itself is symmetric relative to correct ordinal position, but is skewed by other factors (reward, etc.). Tuning width increases with list length, with a concurrent increased use of item-to-item associations for determining touch order.
序列顺序记忆的潜在机制是什么？对前语言序列记忆的研究表明，猕猴在重现一系列物品时能够获得物品顺序位置的知识。在我们之前的实验中，猕猴被反复呈现图像列表（首先按顺序展示，然后同时在触摸屏上展示，同时还有一个从其他列表中随机选择的干扰项）。任务是按正确顺序触摸列表图像。猕猴的自然倾向是根据图像的顺序位置或数字对图像进行分类，因为它们最常见的错误是当干扰项与正确图像具有相同的顺序编号（在其自己的列表中）时触摸干扰项。物品与物品之间的关联被用于完成分类策略。基于序列回忆的动态图像显著性假设（基于类别对图像的影响以及用于识别触摸目标的显著性计算），我们现在在这个假设的背景下研究类别标签的特征。我们发现这些类别标签是基于绝对顺序编号的类别（第一、第二等），不是作为与列表开头和结尾的相对距离来记忆的相对类别，也不是基于奖励偶然性/图像熟悉度的固定排名。即使与物品与物品之间的关联隔离开来，这些类别也表现出类别调谐（以及相邻顺序编号代码的相应重叠）。此外，猕猴根据其类别与当前触摸编号的接近程度来选择图像，而不管前一次选择的准确性如何。类别调谐本身相对于正确的顺序位置是对称的，但会受到其他因素（奖励等）的影响而发生偏移。调谐宽度随着列表长度的增加而增加，同时在确定触摸顺序时对物品与物品之间关联的使用也相应增加。
