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1.
The preattentive emperor has no clothes: a dynamic redressing   总被引:5,自引:0,他引:5  
Preattentive models of early vision have not been supported by the evidence. Instead, an input filtering system, which is dynamically reconfigured so as to optimize performance on the task at hand, is proposed. As a case in point, the authors examined Sagi and Julesz's (1985a) claim that detection tasks are processed preattentively and efficiently (shallow search slopes), whereas discrimination tasks require focal attention and yield inefficient steep slopes. In 5 visual search experiments, efficiency was found to depend not on the nature of the task but on whether the task is single or dual. The second component of a dual task, whether detection or discrimination, is performed inefficiently if it does not fit the configuration of the input system, which had been set optimally for the first component. But, even the second component is processed efficiently if there is enough time to reconfigure the system after processing the first component.  相似文献   

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Once upon a time there was an emperor who was very vain about his elegant clothing. Two swindlers convinced him that they could make him the finest clothes he ever had, and set to work on an empty loom. Rumors of their fame began to spread, and even the emperor's high officials were convinced that the invisible garments were the finest they had ever seen. One minister even decided, “I know I'm not stupid, so it must be my fine position I'm not fit for. Some people might think that rather funny, but I must take good care they don't get to hear of it.” And then he praised the material which he couldn't see and assured them of his delight in its charming shades and its beautiful design. The emperor finally went on parade with his new garments. Crowds gathered, and they all said how magnificently clad he was. No one dared admit they couldn't see the clothes, and many concluded there was simply something wrong with them that he appeared naked. Finally a little child said, “But he hasn't got anything on!” “Goodness gracious, do you hear what the little innocent says?” one whispered to another, until finally everyone shouted at last, “He hasn't got anything on!” The emperor was embarrassed, but he drew himself up and went on with the procession still more proudly, while his chamberlains walked after him carrying the train that wasn't there.  相似文献   

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In this study, we investigated whether or not the reconfiguration of a set task could modulate the efficiency of feature search. In Experiment 1, target set size was manipulated. The results revealed that enumerating targets defined by color yields a much steeper slope when executed simultaneously with a discrimination task than when done singly. However, when distractor set size was manipulated, there was no significant difference in the efficiency of individualizing targets from distractors between the two task conditions, no matter whetherthe search was guided by bottom-up information (Experiment 2) or top-down information (Experiment 3). Drawing upon these results, the authors propose that (1) an additional task can impair the efficiency of enumeration, resulting in a steep slope of counting even when target set size is quite small, and (2) in feature search, the visual system first reconfigures the task set to match the input feature information and then detects the targets with an optimal efficiency, which does not support the theory proposed by Di Lollo, Kawahara, Zuvic, and Visser (2001; Di Lollo, Smilek, Kawahara, & Ghorashi, 2005).  相似文献   

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People confined to a closed space live in a visual environment that differs from a natural open-space environment in several respects. The view is restricted to no more than a few meters, and nearby objects cannot be perceived relative to the position of a horizon. Thus, one might expect to find changes in visual space perception as a consequence of the prolonged experience of confinement. The subjects in our experimental study were participants of the Mars-500 project and spent nearly a year and a half isolated from the outside world during a simulated mission to Mars. The participants were presented with a battery of computer-based psychophysical tests examining their performance on various 3-D perception tasks, and we monitored changes in their perceptual performance throughout their confinement. Contrary to our expectations, no serious effect of the confinement on the crewmembers’ 3-D perception was observed in any experiment. Several interpretations of these findings are discussed, including the possibilities that (1) the crewmembers’ 3-D perception really did not change significantly, (2) changes in 3-D perception were manifested in the precision rather than the accuracy of perceptual judgments, and/or (3) the experimental conditions and the group sample were problematic.  相似文献   

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The extent to which a representation of the reinforcer controls an instrumental response can be assessed by studying the effect of post-conditioning changes in the reinforcer value. In the first experiment rats were trained to press a lever for sucrose pellets on a variable-interval (VI) schedule. The sucrose was subsequently devalued by pairing with Lithium Chloride (LiCl). This had no effect on lever pressing in extinction, although it profoundly reduced reacquisition responding and consumption. In Experiment II rats were trained to shuttle between the two distinctive chambers of a choice-box, in which lever pressing was reinforced in one chamber by sucrose and in the other chamber by food pellets programmed on independent VI schedules. A LiCl-induced taste-aversion was conditioned to the sucrose, and although this markedly affected reacquisition, extinction responding in the sucrose chamber and chamber preference were unaffected. These results indicate that instrumental performance can be independent of the current value of the reinforcer, and are discussed with reference to stimulus-response theory and second-order Pavlovian conditioning.  相似文献   

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We address points raised by Zajonc and Sulloway, who reject findings showing that birth order has no effect on intelligence. Many objections to findings of null birth-order results seem to stem from a misunderstanding of the difference between study designs where birth order is confounded with true causal influences on intelligence across families and designs that control for some of these influences. We discuss some of the consequences of not appreciating the nature of this difference. When between-family confounds are controlled using appropriate study designs and techniques such as multilevel modeling, birth order is shown not to influence intelligence. We conclude with an empirical investigation of the replicability and generalizability of this approach.  相似文献   

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汪天文 《周易研究》2005,2(4):64-71
每一个文明都有自己存在的理由和发展的逻辑线路,不同文明可以有不同的发展程度,但不能有凌驾于其他文明之上的话语解释权.近代科学作为近代西方文明的产物,也同时是古代多种文明融合的产物.科学发展离不开自身所属的文化逻辑,但反过来具备同等文化逻辑的文明未必就一定产生科学.科学作为文化的一种形态,它没有必要成为所有文明的必经之路.我们在尊重、发展作为现代化工具的科学技术的同时,要反对用科学话语来解释工具之上的东西.  相似文献   

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Myors (1998) showed how to combine familiar video page switching with bit-plane layering in video mode 0dh to increase the capacity of the PC tachistoscope from 8 to 32 pages. The present article shows how to combine video page switching with color page switching to implement a 240-page tachistoscope, thus producing an almost eightfold increase in the capacity of the PC tachistoscope. The main limitation of this technique is that the images cannot all be located in the same position on the screen. Complete source code in C is included.  相似文献   

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Page switching is the basis of the PC tachistoscope, and usual accounts of page switching on the PC refer to a maximum of 8 available pages. This article shows how to achieve up to 16 pages in 40-column text mode and up to 32 pages in low-resolution graphics mode using conventional page switching combined with the bit-plane layering technique described by Bokhorst (1995). A high level C program is presented to show how this is done. When 32 pages are in use, the images must be monochrome.  相似文献   

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