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H. Deubel, B. Wesenick, W. X. Schneider; Evidence for nevelty pop-out in visual working memory. Journal of Vision 2001;1(3):215. doi: 10.1167/1.3.215.
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© ARVO (1962-2015); The Authors (2016-present)
The overall performance of visual working memory is determined by various factors such as encoding limitations, memory capacity, rehearsal or retrieval. The present study focusses on the issue of retrieval of information from visual memory. Subjects were shown a memory set containing 1 – 6 multidimensional geometrical objects (rectangles of certain orientation, colour and length) which had to be retained for 0 – 4 sec and then to be compared with a test display. In different experimental blocks we varied three aspects related to the retrieval process: The first aspect concerned the way memory information is requested by the test display: The test display could either consist in a single object — the subject had then to decide whether this object had appeared at the same location in the memory set — or the test display consisted of the same number of objects as shown before with a 50% probability of one of the objects being different. The results show that performance is similar in both conditions, yielding a memory capacity of 3 – 4 objects. The second aspect concerned the type of comparison task: In another experimental condition either all objects in the test display or all objects except of one were different from the memory set — here the subjects had to indicate whether they had detected an unchanged object (“detect match”). Surprisingly, performance in the “detect match” task is drastically deteriorated, yielding an apparent memory capacity on only one item. The third aspect concerned the effect of a cue presented in the retention period at the location of relevant item. The results show that cue presentation improves memory performance in all conditions, most dramatically in the “detect match” condition. The results lead us to the assumption that a fast and automatic process can indicate effectively whether the test display contains a new object compared to the retained information or whether it is identical. We introduce the theoretical notion of a “change signal” that is generated by the cognitive system when new information is processed.. Such a mechanism would bias the organism to attend to novel stimuli — an ability important for coherent and organized behaviour. The findings are consistent with neurophysiological evidence for a neural mechanism that is sensitive to novelty and familiarity.
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