Schoonveld Wade, Shimozaki Steve S, Eckstein Miguel P
Department of Psychology, University of California, Santa Barbara, CA 93106, USA.
J Vis. 2007 Jul 6;7(10):1.1-16. doi: 10.1167/7.10.1.
A common finding in oddity search, a search in which the target is unknown but defined to be different from the distractors, is that human performance remains insensitive or even improves with number of distractors (set size). A number of explanations based on perceptual and attentional mechanisms have been proposed to explain the anomalous set-size effect. Here, we consider whether the shallower set-size function for oddity search could be explained by stimulus information and task demands. We developed an ideal-observer and a difference-coding (standard-deviation) model for single-fixation oddity search and compared it to the ideal observer in the standard target-known search as well as to human performance in both search tasks. Performance for the ideal and difference-coding model in the oddity search resulted in a shallower set-size function than the target-known ideal observer and was a good predictor of human search accuracy. However, the ideal-observer model was a better predictor than the standard-deviation model for 10 of the 12 data sets. The results highlight the importance of using ideal-observer analysis to separate contributions to human performance arising from perceptual/attentional mechanisms inherent to the human brain from those contributions arising from differences in stimulus information associated with the tasks.
在奇异性搜索（一种目标未知但被定义为与干扰项不同的搜索）中，一个常见的发现是，人类的表现对干扰项数量（集合大小）不敏感，甚至会随着干扰项数量的增加而提高。已经提出了一些基于感知和注意力机制的解释来解释这种异常的集合大小效应。在这里，我们考虑奇异性搜索中较浅的集合大小函数是否可以由刺激信息和任务需求来解释。我们为单注视奇异性搜索开发了一个理想观察者模型和一个差异编码（标准差）模型，并将其与标准的目标已知搜索中的理想观察者以及这两种搜索任务中的人类表现进行了比较。奇异性搜索中理想模型和差异编码模型的表现导致了比目标已知理想观察者更浅的集合大小函数，并且是人类搜索准确性的良好预测指标。然而，在12个数据集中的10个数据集中，理想观察者模型比标准差模型是更好的预测指标。这些结果突出了使用理想观察者分析的重要性，以便将人类大脑固有的感知/注意力机制对人类表现的贡献与任务相关的刺激信息差异所产生的贡献区分开来。
