Constancy of attentional resources in processing cognitive tasks.

这项研究是为了确定每个受试者在处理视觉信息时的注意资源量是否保持恒定，即使当注意力分配通过改变视觉目标的数量或其呈现的概率而改变时也是如此。实验一以对目标字母的反应时为指标，将其中一个目标字母呈现在视场中的水平或垂直位置，并用声音告诉被试对目标做出反应。当呈现目标的定向分离的数量从1个增加到4个时，性能被发现下降。当字母的呈现概率随方向不同而变化时，与每个方向的概率相等的条件相比，高概率方向的表现提高，其他方向的表现降低。第二个实验的目的是在目标字母呈现在视野中央的条件下，更密切地检验资源恒定的假设。在等概率条件下，每个字母的性能随着字母数量从一个增加到四个而增加。与等概率条件相比，增加一个字母的概率提高了它的表现，但减少了可用于其他字母的资源。这些实验表明，处理视觉信息的能力是有限的，分配给每个受试者处理每个目标的注意资源量保持不变。

This research were undertaken in order to determine whether the amount of attentional resources in processing a visual information remain constant for each subject, even when allocation of attention was changed by varying the visual targets in number, or the probabilities of their presentation. Reaction time to a target letter was used as the measure of resourses allocated to it.In the first experiment, one of the target letters were presented in a position of horizontal or vertical directions in the visual field, and subjects were told vocally to react to the targets. Performances were found to decrease as the directional separation, in which targets were presented, increased in number from one to four. When the probabilities of presentation for the letters were varied with the directions, performance for higher-probability direction increased, and performance for other direction decreased, in comparison with conditions in which the probabilities of each direction were equal.The objective of the second experiment was to examine more closely the assumption of the constancy of resources, under the conditions that one of the target letters presented in the center of the visual field. In the equal-probability condition, performance for each letter increased as the number of letters used increased from one to four. Increased probability for one letter improved performance on it, but reduced the resources available for other letters, in comparison with equal-probability condition.These experiments have revealed that there is a limit in ability of processing visual information, and the amount of attentional resources allocated to processing each target remains constant for each subject.