this memory and can explicitly report details of a changed object in response to probing questions. The results of these real-world change detection studies are discussed in the context of broader claims about change blindness. 2002 Elsevier Science (USA) Our experience of a rich, stable visual world often leads to the intuitive belief that our representations of that world are correspondingly detailed and precise. But increasing evidence for "change blindness," the inability to detect large changes to scenes from one glance to the next, has inspired claims that little to no information about the world is preserved in visual short term memory (e.g., O'Regan, 1992; Rensink, 2000a, 2000b). Such claims have some historical precedents (e.g., Gibson, 1986/1979; Hochberg, 1986; Stroud, 1955), but they do not necessarily follow from change blindness. Change blindness could occur for many reasons, even when observers have representations of the pre-change scene (Simons, 2000b). For example, change blindness could reflect a failure to compare representations of the pre- and post-change scene. Here, we present evidence that supports this possibility by showing that some subjects who fail to report a change can subsequently report features of the pre-change object when asked

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this paper. Third, we did not use the exact colors tested by the previouslycited authors. They used four CIE colors that were difficult to reproduce with our equipment. We used eight RGB colors. It is unclear which set of colors is more representative of the basis of VSTM. Hence, it is important to test more than one set of colors in additionalexperiments. Finally, whereas observers in Luck and Vogel's (1997) study carried out an articulatory suppression task concur- Figure 2. Results from Experiment 1, with mean accuracy as a function of condition and the number of memory objects. Error bars represent standard error of the mean

PSYCHE an interdisciplinary journal of research on consciousness

this paper we will refer to these three types of properties as individuality, spatiotemporal properties and featural properties.

It is well known that under normal circumstances, human observers are able to detect a visual change (a luminance transient) in the outside world very easily. This study demonstrated that observers are also easily able to detect a nonchanging element if it is located in a display containing multiple elements that do change. That is, a nonchanging element popped out from a display containing multiple changing elements (luminance transients). The efficient detection of the nonchanging element may be due to temporal grouping created by the dynamic character of the stimulus display.

This paper reviews research examining the role of visual memory in scene perception and visual search. Recent theories in these literatures have held that coherent object representations in visual memory are fleeting, disintegrating upon the withdrawal of attention from an object. I discuss evidence demonstrating that, far from being transient, visual memory supports the accumulation of information from scores of individual objects in scenes, utilizing both visual short-term memory and visual long-term memory. In addition, I review evidence that memory for the spatial layout of a scene and memory for specific object positions can efficiently guide search within natural scenes. In the past decade, the interaction between perception and memory has received a great deal of attention from cognitive scientists. Much of this interest has originated from increased understanding that perception is a dynamic, serial process, extended over space and time. In this paper, I will discuss two related lines of research in which the relationship between perception and memory has come to the fore: Scene perception and visual

Large changes in a scene often become difficult to notice if made during an eye movement, image flicker, movie cut, or other such disturbance. It is argued here that this change blindness can serve as a useful tool to explore various aspects of vision. This argument centers around the proposal that focused attention is needed for the explicit perception of change. Given this, the study of change perception can provide a useful way to determine the nature of visual attention, and to cast new light on the way that it is — and is not — involved in visual perception. To illustrate the power of this approach, this paper surveys its use in exploring three different aspects of vision. The first concerns the general nature of seeing. To explain why change blindness can be easily induced in experiments but apparently not in everyday life, it is proposed that perception involves a �irtual representation, where object representations do not accumulate, but are formed as needed. An architecture containing both attentional and nonattentional streams is proposed as a way to implement this scheme. The second aspect concerns the ability of observers to detect change even when they have no visual experience of it. This sensing is found to take on at least two forms: detection without visual experience (but still with conscious awareness), and detection without any awareness at all. It is proposed that these are both due to the operation of a nonattentional visual stream. The final aspect considered is the nature of visual attention itself — the mechanisms involved when scrutinizing items. Experiments using controlled stimuli show the existence of various limits on visual search for change. It is shown that these limits provide a powerful means to map out the attentional mechanisms involved. © 2000

Intuitively, dynamic visual stimuli, such as moving objects or flashing lights, attract attention. Visual search tasks have revealed that dynamic targets among static distractors can indeed efficiently guide attention. The present study shows that the reverse case, a static target among dynamic distractors, allows for relatively efficient selection in certain but not all cases. A static target was relatively efficiently found among distractors that featured apparent motion, corroborating earlier findings. The important new finding was that static targets were equally easily found among distractors that blinked on and off continuously, even when each individual item blinked at a random rate. However, search for a static target was less efficient when distractors abruptly varied in luminance but did not completely disappear. The authors suggest that the division into the parvocellular pathway dealing with static visual information, on the one hand, and the magnocellular pathway common to motion and new object onset detection, on the other hand, allows for efficient filtering of dynamic and static information.

this paper benefited from support provided by NIH Grant R01-HD23922 to Frank Keil