Meaningful visual experience requires computations that identify objects as the same persisting individuals over time, motion, occlusion, and featural change. This article explores these computations in the tunnel effect: When an object moves behind an occluder, and then an object later emerges following a consistent trajectory, observers irresistibly perceive a persisting object, even when the pre- and postocclusion views contrast featurally. This article introduces a new change detection method for quantifying percepts of the tunnel effect. Observers had to detect color changes in displays where several objects oscillated behind occluders and occasionally changed color. Across comparisons with several types of spatiotemporal gaps, as well as manipulations of occlusion versus implosion, performance was better when objects ’ kinematics gave the impression of a persisting individual. The results reveal a temporal same-object advantage: better change detection across temporal scene fragments bound into the same persisting object representations. This suggests that persisting objects are the underlying units of visual memory.

The ability to remember visual stimuli over a short delay period is limited by the small capacity of visual working memory (VWM). Here the authors investigate the role of learning in enhancing VWM. Participants saw 2 spatial arrays separated by a 1-s interval. The 2 arrays were identical except for 1 location. Participants had to detect the difference. Unknown to the participants, some spatial arrays would repeat once every dozen trials or so for up to 32 repetitions. Spatial VWM performance increased significantly when the same location changed across display repetitions, but not at all when different locations changed from one display repetition to another. The authors suggest that a major role of learning in VWM is to mediate which information gets retained, rather than to directly increase VWM capacity.

Two dot arrays, each containing a different set of 6 randomly selected locations from a 5x5 matrix, were presented briefly and separated by an inter-stimulusinterval (ISI) of 0, 200, 500, or 1500ms. Subjects were asked to remember these locations and to report whether a probe dot matched the memory locations. To find out whether subjects formed an integrated representation of the two arrays, the probe dot was accompanied by matrix elements from the first array, from the second array, or from both arrays. Memory for array 1 was significantly impaired when the retrieval context was drawn from array 2, and vice versa, suggesting that the two arrays were represented separately. This effect was observed only at an ISI of 500ms or longer. We propose that as array 1 is better consolidated, it representation becomes more separated from that of array 2. 2 An important challenge confronting the human visual system during natural viewing is to extract complex visual information and to retain it momentarily. A lot of vision research has focused on how the visual system perceives objects and scenes (Palmer, 1999), and how such information is retained in visual short-term memory (Intraub, 1997; Jiang, Olson, & Chun, 2000; Luck & Vogel, 1997; Phillips, 1974; Rensink, O'Regan, & Clark, 1997; Wheeler & Treisman, 2002). Recent studies suggest that approximately four visual objects or six spatial locations can be stored in VSTM simultaneously (Luck & Vogel, 1997; Pashler, 1988). More features can be stored in VSTM if they conjoin to form integrated objects than if they are separate (Lee & Chun, 2001; Luck & Vogel, 1997; Olson & Jiang, 2002; Xu, 2002; Wheeler & Treisman, 2001). These studies have focused on the representation of a single visual display in VSTM. However, visual events evolv...

The information that individuals can hold in working memory is quite limited, but researchers have typically studied this capacity using simple objects or letter strings with no associations between them. However, in the real world there are strong associations and regularities in the input. In an information theoretic sense, regularities introduce redundancies that make the input more compressible. The current study shows that observers can take advantage of these redundancies, enabling them to remember more items in working memory. In 2 experiments, covariance was introduced between colors in a display so that over trials some color pairs were more likely to appear than other color pairs. Observers remembered more items from these displays than from displays where the colors were paired randomly. The improved memory performance cannot be explained by simply guessing the high-probability color pair, suggesting that observers formed more efficient representations to remember more items. Further, as observers learned the regularities, their working memory performance improved in a way that is quantitatively predicted by a Bayesian learning model and optimal encoding scheme. These results suggest that the underlying capacity of the individuals ’ working memory is unchanged, but the information they have to remember can be encoded in a more compressed fashion.

Two studies compared young and older adults ’ memory for location information after brief intervals. Experiment 1 found that accuracy of intentional spatial memory for individual locations was similar in young and older participants for set sizes of 3 and 6. Both groups also encoded individual locations in relation to the larger configuration of locations. Experiment 2 showed that like young adults, older adults’ latency to respond to a test probe in a letter working memory task was negatively influenced by spatial information that was irrelevant to the task. This interference effect indicated preserved incidental memory for spatial information in older adults. Together, these data suggest that initial encoding of spatial information for relatively small numbers of items is largely preserved in healthy older adults and that representations of spatial information persist over short intervals. The nature of memory deficits associated with aging has received increasing attention over the last 15–20 years. Many studies have now reported age-related differences in long-term episodic memory and working memory (see, e.g., Anderson & Craik, 2000; Balota, Dolan, & Duchek, 2000; Zacks, Hasher, & Li, 2000, for reviews). Furthermore, age-related deficits in memory typically are greater for tests assessing which features go together (binding, context, source, or associative memory) than for tests assessing individual features or item information (e.g., Benjamin & Craik,

Past research has investigated the capacity of visual short-term memory (VSTM) for a single visual display, but has only recently begun to explore VSTM for multiple sequential arrays. In this study, we investigate the capacity of VSTM across two sequential arrays separated by a variable stimulus-onset-asynchrony (SOA). VSTM for spatial locations (Experiment 1), colors (Experiments 2-4), orientations (Experiments 3-4), and conjunction of color and orientation (Experiment 4) are tested, when the SOA across two sequential arrays varies between 100ms and 1500ms. We find that VSTM for the trailing array is much better than VSTM for the leading array, but when averaged across the two arrays, VSTM has a constant capacity independent of the SOA. We suggest that multiple displays compete for retention in VSTM, and that separating information into two temporally discrete groups does not enhance the overall capacity of VSTM.

The world is composed of features and objects and this structure may influence what is stored in working memory. It is widely believed that the content of memory is object-based: Memory stores integrated objects, not independent features. We asked participants to report the color and orientation of an object and found that memory errors were largely independent: Even when one of the object’s features was entirely forgotten, the other feature was often reported. This finding contradicts object-based models and challenges fundamental assumptions about the organization of information in working memory. We propose an alternative framework involving independent self-sustaining representations that may fail probabilistically and independently for each feature. This account predicts that the degree of independence in feature storage is determined by the degree of overlap in neural coding during perception. Consistent with this prediction, we found that errors for jointly encoded dimensions were less independent than errors for independently encoded dimensions.

Shape and color conjunction stimuli are represented as bound objects in visual

Abstract. Does the maintenance of feature bindings in visual short-term memory (VSTM) require sustained focused attention? This issue was investigated in three experiments, in which memory for single features (i.e., colors or shapes) was compared with memory for feature bindings (i.e., the link between the color and shape of an object). Attention was manipulated during the memory retention interval with a retro-cue, which allows attention to be directed and focused on a subset of memory items. The retro-cue was presented 700 ms after the offset of the memory display and 700 ms before the onset of the test display. If the maintenance of feature bindings – but not of individual features – in memory requires sustained focused attention, the retro-cue should not affect memory performance. Contrary to this prediction, we found that both memory for feature bindings and memory for individual features were equally improved by the retro-cue. Therefore, this finding does not support the view that the sustained focused attention is needed to properly maintain feature bindings in VSTM.