Postattentive vision

Much research has examined preattentive vision: visual representation prior to the arrival of attention. Most vision research concerns attended visual stimuli; very little research has considered postattentive vision. What is the visual representation of a previously attended object once attention is deployed elsewhere? The authors argue that perceptual effects of attention vanish once attention is redeployed. Experiments 1-6 were visual search studies. In standard search, participants looked for a target item among distractor items. On each trial, a new search display was presented. These tasks were compared to repeated search tasks in which the search display was not changed. On successive trials, participants searched the same display for new targets. Results showed that if search was inefficient when participants searched a display the first time, it was inefficient when the same, unchanging display was searched the second, fifth, or 350th time. Experiments 7 and 8 made a similar point with a curve tracing paradigm. The results have implications for an understanding of scene perception, change detection, and the relationship of vision to memory.     

Computational theories of vision

This exciting and original book describes the work of David Marr and his colleagues at MIT on the computational theory of vision, particularly the early stages of shape analysis. Although much of the theorising is frankly speculative and not certain to survive without major modification, it sets new standards of rigour in its formal approach and is certain to have a stimulating effect upon the field. Sadly, Marr's death from leukaemia at the age of 35 means that he will not himself be able to take part in the further development of his ideas, but the book itself will exert an important influence for some time to come. The first point to make, for those who may already have attempted Marr's lengthy and difficult research papers, is that the book is clearly and entertainingly written: It can be tackled by the non-specialist who wishes to see why Marr's work has caused such interest in the vision community. Despite the very difficult circumstances in which the book must have been written, it is carefully put together and gives a fascinating insight into the way in which the author's ideas developed.     

Sound and vision

When a brief flash appears at the same position as a moving object, the flash is perceived to lag behind. This so-called flash-lag effect tells us something about the perception of space and time: where is the moving object when the flash appears? A recent paper by Alais and Burr on auditory and crossmodal flash-lag effects indicates that our (often implicit) models of the perception of space and time might be flawed.     

Mathematical leadership vision

This article is an analysis of a new type of leadership vision, the kind of vision that is becoming increasingly pervasive among leaders in the modern world. This vision appears to offer a new horizon, whereas, in fact it delivers to its target audience a finely tuned version of the already existing ambitions and aspirations of the target audience. The leader, with advisors, has examined the target audience and has used the results of extensive research and statistical methods concerning the group to form a picture of its members' lifestyles and values. On the basis of this information, the leader has built a "vision." The vision is intended to create an impression of a charismatic and transformational leader when, in fact, it is merely a response. The systemic, arithmetic, and statistical methods employed in this operation have led to the coining of the terms mathematical leader and mathematical vision.     

The indeterminacy of color vision

A critical survey of recent work on the ontological status of colors supports the conclusion that, while some accounts of color can plausibly be dismissed, no single account can yet be endorsed. Among the remaining options are certain forms of color realism according which familiar colors are instantiated by objects in our extra-cranial visual environment. Also still an option is color anti-realism, the view that familiar colors are, at best, biologically adaptive fictions, instantiated nowhere.I argue that there is simply no fact of the matter as to which of these remaining options is correct. I blame this indeterminacy on the fact that color vision exhibits several of the hallmarks of a modular input system, as described by Jerry Fodor in The Modularity of Mind.Finally, I speculate that the range of live options falling within the scope of the indeterminacy may be even broader than initially indicated.     

On selection in vision

Summary The discrepancy between the capabilities of perceptual systems and effector systems makes mechanisms necessary that can selectively designate a subset of the perceptual information available to control an action. In vision, since foveation is neither sufficient nor necessary for this selection, central selection mechanisms have to be postulated. This study is concerned with the question of at what level this central selection takes place in one type of task, the partial-report bar-probe task. Two theories are relevant: early selection theories, asserting that central selection operates in a stage containing rapidly decaying precategorical visual information, and late selection theories, arguing that central selection operates in a stage containing abstract categorical information. A prediction following from the assumptions of early selection theories, but not of late selection theories, is that in bar-probe tasks the function relating the number of visual confusions to probe delays has to exhibit an inverted-U shape. This prediction was tested in five experiments, two with colors as items and three with letters. In all experiments, the proportion of visual confusions first increased with increasing probe delays and then decreased with still larger probe delays. The results support the early selection theories for small probe delays. For larger probe delays, late selection has to be postulated.     

Spatial attention in vision

Summary Human observers can selectively allocate processing resources to different areas of the visual field within a single fixation. This spatial attention system may affect either the quality of information extraction or the decisions and responses based on this information. This paper reviews evidence from behavioral, single-unit, and event-related potential paradigms; the evidence suggests a relatively early locus of spatial attention.This research was supported by the U. S. Army Research Office under contract DAAG 29-83-K-0049. Portions of this paper were presented to the Conference on Attention and Action, Bielefeld, West Germany, in July 1985     

Harnessing vision for computation

Might it be possible to harness the visual system to carry out artificial computations, somewhat akin to how DNA has been harnessed to carry out computation? I provide the beginnings of a research programme attempting to do this. In particular, new techniques are described for building 'visual circuits' (or 'visual software') using wire, NOT, OR, and AND gates in a visual 6modality such that our visual system acts as 'visual hardware' computing the circuit, and generating a resultant perception which is the output.     

宗教信徒之视野

宗教作为一种社会意识形态,对社会存在的反映有其特殊的方式,这种反映方式使信徒与非信徒有所区别。本文以宗教信徒与非宗教信徒之共处的社会环境为背景,在逐次排除其反映社会生活的共同方面的基础上,从而引出两者对社会生活反映方式的根本差别,就在于信徒有着对社会生活的双重视野及价值标准,而这也正是信徒所特有的,并一直被宗教所传承的共性。     

Elemental operations in vision

Many cognitive tasks are serial in that they require several steps that have to be carried out in a sequence. Here, I outline a new theory of how these processing steps are implemented in vision by networks of neurons that span several areas of the cerebral cortex. The theory explains how individual neurons can contribute to the elementary processing steps, and also how several processing steps can be arranged in a sequence to form more complex visual routines, just as computer programs can be composed of sequences of instructions. Evidence in support of the theory comes from recent neurophysiological findings in monkeys engaged in complex visual tasks. It is likely that future work will allow these ideas to be generalized to other sensory modalities and cognitive functions.