空间距离对视觉工作记忆巩固的影响

以往研究发现,个体对不同类型的视觉信息进行视觉工作记忆巩固的模式存在差异,如对于方向信息,一次只能有一个项目被巩固进入视觉工作记忆系统,而对于颜色信息,个体则可以一次巩固两个项目进入视觉工作记忆系统。但对于视觉信息的巩固模式是否会受其他因素的影响,目前仍然没有明确的定论。本研究将探讨视觉信息的巩固模式是否可能受到记忆项目空间距离因素的影响。研究采用变化觉察范式、序列-同时呈现操作及控制记忆项目呈现间距的方法,通过3个实验考察记忆项目之间的空间距离是否能够影响个体对颜色信息和方向信息的巩固模式。在三种空间距离水平上序列呈现或同时呈现两个记忆项目,实验结果一致发现记忆项目之间的空间距离会对视觉工作记忆巩固模式产生明显影响,个体在同时呈现条件下的正确率会随着空间距离的增大而降低。这些结果表明对同一类视觉信息进行巩固的过程中所存在的项目数量限制并不是固定的,个体可以采用序列模式或有限容量的并行模式对同一类信息进行巩固,巩固的模式可能与视觉空间注意的分配以及视觉信息所能获得的注意资源有关。     

A severe capacity limit in the consolidation of orientation information into visual short-term memory

Previous research has suggested that two color patches can be consolidated into visual short-term memory (VSTM) via an unlimited parallel process. Here we examined whether the same unlimited-capacity parallel process occurs for two oriented grating patches. Participants viewed two gratings that were presented briefly and masked. In blocks of trials, the gratings were presented either simultaneously or sequentially. In Experiments 1 and 2, the presentation of the stimuli was followed by a location cue that indicated the grating on which to base one’s response. In Experiment 1, participants responded whether the target grating was oriented clockwise or counterclockwise with respect to vertical. In Experiment 2, participants indicated whether the target grating was oriented along one of the cardinal directions (vertical or horizontal) or was obliquely oriented. Finally, in Experiment 3, the location cue was replaced with a third grating that appeared at fixation, and participants indicated whether either of the two test gratings matched this probe. Despite the fact that these responses required fairly coarse coding of the orientation information, across all methods of responding we found superior performance for sequential over simultaneous presentations. These findings suggest that the consolidation of oriented gratings into VSTM is severely limited in capacity and differs from the consolidation of color information.     

Parallel consolidation of simple features into visual short-term memory

Although considerable research has examined the storage limits of visual short-term memory (VSTM), little is known about the initial formation (i.e., the consolidation) of VSTM representations. A few previous studies have estimated the capacity of consolidation to be one item at a time. Here we used a sequential-simultaneous manipulation to reexamine the limits of consolidating items into VSTM. Participants viewed briefly presented and masked color patches (targets), which were shown either sequentially or simultaneously. A probe color followed the targets and participants decided whether it matched one of the targets or was a novel color. In four experiments, we consistently found equal performance for sequential and simultaneous presentations for two targets. Worse performance in the simultaneous than the sequential condition was observed for larger set sizes (three and four). Contrary to previous results, suggesting a severe capacity limit of one item, our results indicate that consolidation into VSTM can occur in parallel and without capacity limits for at least two items.     

On the degree of attention and capacity limitations in visual processing

The ability to detect simple types of visual information from various locations in the visual field was examined in two experiments. In both, the four locations containing the information to be detected were presented either simultaneously or sequentially, with the presentation time per location identical for both conditions. Limitations of capacity and attentional control of perceptual processing would predict sequential presentation to be superior to simultaneous presentation, since, in the former case, attention need not be shared among four locations. The results showed equal detection performance for both conditions. Thus, spatial attention was not present during detection of horizontal and vertical dot pairs (Experiment I). O differences (probably due to strategies) make the same conclusion more difficult to draw for single-dot detection (Experiment II). Similar findings and conclusions were reported by Shiffrin and Gardner (1972) in studies utilizing alphabetic characters.     

Working memory binding of visual object features in older adults

Accurate mental representation of visual stimuli requires retaining not only the individual features but also the correct relationship between them. This associative process of binding is mediated by working memory (WM) mechanisms. The present study re-examined reports of WM-related binding deficits with aging. In Experiment 1, 31 older and 31 younger adults completed a visual change detection task with feature–location relations presented either simultaneously or sequentially; the paradigm was also designed specifically to minimize the impact of lengthy retention intervals, elaborative rehearsal, and processing demands of multi-stimulus probes. In Experiment 2, 38 older and 42 younger adults completed a modified task containing both feature–location relations and feature–feature conjunctions. In Experiment 1 although feature–location binding was more difficult with sequential compared with simultaneous presentation, the effect was independent of age. In Experiment 2 while older adults were overall slower and less accurate than young adults, there were no age-specific deficits in WM binding. Overall, after controlling for methodological factors, there was no evidence of an age-related visual WM binding deficit for surface or location features. However, unlike younger adults, older adults appeared less able to restrict processing of irrelevant features, consistent with reported declines with age in strategic capacities of WM.     

Perceptual learning in visual conjunction search.

Perceptual learning in colour/orientation visual conjunction search was examined in five experiments. Good transfer occurred to other conjunction arrays when only one element of the conjunction (either colour or orientation) was changed. When both elements (colour and orientation) were changed, but the same feature spaces were used (i.e. other colours and orientations) or when a new dimension was introduced to the transfer task (shapes instead of orientation), transfer was poor. The results suggest that perceptual learning of visual conjunction search is constrained mainly by stimulus parameters rather than by changes in cognitive strategies which are common to all search tasks. Contrary to other reports we found little evidence of long-term retention of learning.     

Correspondence problems cause repositioning costs in visual working memory

Visual working memory performance often declines when objects are tested in new positions from those they were observed. We report an asymmetry in repositioning costs for orientation compared to colour memory (Experiment 1). Follow-up experiments demonstrated a similar asymmetry for line length memory compared to shape memory (Experiment 2). When different shades of the same colour category were used, however, repositioning costs emerged for colour as well (Experiment 3). Finally, a direct comparison experiment demonstrated an asymmetry for orientation compared to categorical colours, but in a task with no explicit memory demands (Experiment 4). These results challenge previous accounts of repositioning costs, suggesting that they emerge not due to the contents of visual working memory, but naturally because of correspondence procedures that must be executed in order to use a memory to judge the present.     

Transfer of serial reversal learning in the pigeon

Pigeons were trained on a series of reversals of a simultaneous visual discrimination and were then shifted to a second series of reversals with different visual discriminanda. Pigeons that were given discrimination reversals with one pair of colours (Group Colour) and then shifted to a second pair of colours made fewer errors with the second pair than the first. In contrast, pigeons that were initially given reversals with a pair of orientations (Group Orientation) and then shifted to colours made as many errors during colour reversals as Group Colour had during initial colour training. When birds in Group Colour were subsequently shifted to orientation discrimination reversals, they performed no better than Group Orientation had during initial orientation training. The present results suggest that positive transfer from one series of discrimination reversals to a second, independent series may be constrained by the nature of the stimulus shift.     

注意范围分布对视觉工作记忆巩固过程的影响

以往研究发现个体能够同时巩固一定数量的项目信息进入视觉工作记忆系统。本研究将考察视觉工作记忆的巩固容量是否会受到分配到记忆项目上的注意资源量的影响。实验1在同时序列掩蔽范式的基础上, 用控制记忆项目呈现区域的大小的方法操纵被试的注意范围, 从而达到操纵分配到单个项目上的注意资源量的目的。研究结果显示, 被试的记忆成绩随着注意范围的扩大显著降低, 但在并行和序列呈现条件之间不存在显著差异; 实验2则证实实验1中对注意资源量分配的控制不会影响对项目的知觉编码效率。本研究结果表明, 分配在记忆项目上的注意资源量能够影响记忆巩固的效率, 但不会影响巩固容量。     

Sequential versus simultaneous viewing of an environment: Effects of focal attention to individual object locations on visual spatial learning

We investigated memories of room-sized spatial layouts learned by sequentially or simultaneously viewing objects from a stationary position. In three experiments, sequential viewing (one or two objects at a time) yielded subsequent memory performance that was equivalent or superior to simultaneous viewing of all objects, even though sequential viewing lacked direct access to the entire layout. This finding was replicated by replacing sequential viewing with directed viewing in which all objects were presented simultaneously and participants’ attention was externally focused on each object sequentially, indicating that the advantage of sequential viewing over simultaneous viewing may have originated from focal attention to individual object locations. These results suggest that memory representation of object-to-object relations can be constructed efficiently by encoding each object location separately, when those locations are defined within a single spatial reference system. These findings highlight the importance of considering object presentation procedures when studying spatial learning mechanisms.     

Recognition in a visuospatial memory task: The effect of presentation

The influence of the mode of presentation (simultaneous vs. sequential) on accuracy and latency of visuospatial recognition was explored in three experiments. In Experiment 1, two groups were administered a visuospatial task in which a number of positions were shown either simultaneously or sequentially (in a random order); memory was tested using a recognition procedure of visuospatial patterns, either identical or different (a single cell displaced). The results showed that (1) performance was higher in the simultaneous than in the sequential presentation, and (2) decision time increased with complexity in the sequential presentation but not in the simultaneous presentation. In Experiment 2, the same task was used in three conditions of presentation, simultaneous, random sequential, and ordered sequential; at test, a single location, rather than a pattern, was presented for recognition. The results showed that (1) performance was higher in the simultaneous and in the ordered sequential presentations than in the random sequential one, and (2) decision time increased with complexity. In Experiment 3, the same task was used in the same three conditions of presentation, simultaneous, random sequential, and ordered sequential; at test either an identical or a “displaced” pattern was presented for recognition. The results showed that (1) performance was equivalent in the three types of presentation, and (2) decision time increased with complexity for “hit” items; different patterns of linear relations were observed for “correct rejections” items. The results are interpreted in terms of the organisation of visuospatial working memory, and three types of encoding—extrafigural spatial encoding, visual pattern encoding, and spatial path encoding—were proposed.     

The influence of similarity on visual working memory representations

In verbal memory, similarity between items in memory often leads to interference and impaired memory performance. The present study sought to determine whether analogous interference effects would be observed in visual working memory by varying the similarity of the to-be-remembered objects in a colour change detection task. Instead of leading to interference and impaired performance, increased similarity among the items being held in memory led to improved performance. Moreover, when two similar colours were presented along with one dissimilar colour, memory performance was better for the similar colours than for the dissimilar colour. Similarity produced better performance even when the objects were presented sequentially and even when memory for the first item in the sequence was tested. These findings show that similarity does not lead to interference between representations in visual working memory. Instead, similarity may lead to improved task performance, possibly due to increased stability or precision of the memory representations during maintenance.     

The perceptual root of object-based storage: an interactive model of perception and visual working memory

Mainstream theories of visual perception assume that visual working memory (VWM) is critical for integrating online perceptual information and constructing coherent visual experiences in changing environments. Given the dynamic interaction between online perception and VWM, we propose that how visual information is processed during visual perception can directly determine how the information is going to be selected, consolidated, and maintained in VWM. We demonstrate the validity of this hypothesis by investigating what kinds of perceptual information can be stored as integrated objects in VWM. Three criteria for object-based storage are introduced: (a) automatic selection of task-irrelevant features, (b) synchronous consolidation of multiple features, and (c) stable maintenance of feature conjunctions. The results show that the outputs of parallel perception meet all three criteria, as opposed to the outputs of serial attentive processing, which fail all three criteria. These results indicate that (a) perception and VWM are not two sequential processes, but are dynamically intertwined; (b) there are dissociated mechanisms in VWM for storing information identified at different stages of perception; and (c) the integrated object representations in VWM originate from the "preattentive" or "proto" objects created by parallel perception. These results suggest how visual perception, attention, and VWM can be explained by a unified framework.     

Object individuation in 3-day-old chicks: use of property and spatiotemporal information

Object individuation was investigated in newborn domestic chicks. Chicks' spontaneous tendency to approach the larger group of familiar objects was exploited in a series of five experiments. In the first experiment newborn chicks were reared for 3 days with objects differing in either colour, shape or size. At test, each chick was presented with two groups of events: two objects differing in one property vs. two presentations of the same object. In both cases, all objects involved in the same group of events were sequentially presented and eventually concealed in a different spatial location, and the number of events taking place at each location was equalized. Chicks spontaneously approached the two different objects rather than the single object seen twice. Chicks did not just prefer the more varied set as they did not choose it when the two elements of each group of events were simultaneously presented (Experiment 2). Chicks succeeded when two different objects simultaneously presented were confronted with three identical ones simultaneously presented (Experiment 3), though they failed with sequential presentation of two different objects vs. one object presented three times if they had been familiarized with up to three identical objects (Experiment 4). Chicks instead succeeded if they had been familiarized with objects that were all different from one another (Experiment 5). These young birds thus proved able to use property and spatiotemporal information for object individuation.     

Perceptual grouping boosts visual working memory capacity and reduces effort during retention

Consistent, robust boosts to visual working memory capacity are observed when colour–location arrays contain duplicate colours. The prevailing explanation suggests that duplicated colours are encoded as one perceptual group. If so, then we should observe not only higher working memory capacity overall for displays containing duplicates, but specifically an improved ability to remember unique colours from displays including duplicates compared with displays comprising all uniquely coloured items. Furthermore, less effort should be required to retain displays as colour redundancy increases. I recorded gaze position and pupil sizes during a visual change detection task including displays of 4–6 items with either all unique colours, two items with a common colour, or three items with a common colour in samples of young and healthy elderly adults. Increased redundancy was indeed associated with higher estimated working memory capacity, both for tests of duplicates and uniquely coloured items. Redundancy was also associated with decreased pupil size during retention, especially in young adults. While elderly adults also benefited from colour redundancy, spillover to unique items was less obvious with low redundancy than in young adults. This experiment confirms previous findings and presents complementary novel evidence linking perceptual grouping via colour redundancy with decreased mental effort.     

Which Is Better: Simultaneous or Sequential Choice?

The term "diversification bias" refers to the tendency for people to take more variety when choosing several items simultaneously than when choosing them sequentially. In this article, we investigate whether this really is a bias by measuring evaluations of sets chosen simultaneously or sequentially. In Experiment 1 participants made two choices between audio tracks for consecutive consumption. Participants liked low-variety sets most and were more likely to choose high-variety sets in simultaneous choice. In Experiment 2 participants chose between three gambles which varied in the probability of winning and their expected value. Again, simultaneous choices seemed worse than sequential ones: The simultaneous-choice groups took far more low expected value gambles than did sequential-choice subjects and rated their enjoyment as lower. We conclude that simultaneous choice often leads to outcomes that are worse than sequential choice and discuss the circumstances when this is likely to be true.     

Auditory versus visual processing of three sets of simultaneous digit pairs.

Two experiments were conducted to determine whether the auditory and visual systems process simultaneously presented pairs of alphanumeric information differently. In Experiment 1, different groups of subjects were given extensive practice recalling pairs of superimposed visual or auditory digits in simultaneous order (the order of arrival) or successive order (one member of each digit pair in turn, followed by the other pair member). For auditory input, successive order of recall was more accurate, particularly for the last two of three pairs presented, whereas for visual input, simultaneous order of recall was more accurate. In Experiment 2, subjects were cued to recall in one or the other order either immediately before or after stimulus input. Recall order results were the same as for Experiment 1, and precuing did not facilitate recall in either order for both modalities. These results suggest that processing in the auditory system can only occur successively across time, whereas as in the visual system processing can only occur simultaneously in space.     

Comparisons of reaction time patterns in a sequential visual recognition task with simple geometric forms

Right isosceles triangles, which differed in size and orientation, were presented in a sequential visual recognition task. Subjects produced an identity match response if the first self-presented stimulus, now in memory, was identical to a sequentially presented stimulus and a nonidentity match response if the subsequently presented stimulus differed in either or both size and orientation. The pattern of nonidentity recognition reaction times produced was compared to predicted patterns deduced from several theories of form information processing. The pattern of responses for both group and individual data were better described by serial and parallel self-terminating models with probabilistic assumptions than they were by template or deterministic serial or parallel models. A second study, in which identity and nonidentity response bias was equated, found that the identity responses were significantly faster than nonidentity responses, supporting wholistic processing for the identity matches and, when combined with the nonidentity match results, supporting a dual process theory.     

Colour specificity in episodic and in perceptual object recognition with enhanced colour impact

In three experiments we investigated the perceptual specificity of explicit (old-new object recognition) and implicit memory (word-picture matching) for colour. In order to enhance the impact of colour on processing, we increased the number of colours per object and we impaired shape information. We presented multicoloured pictures (Experiment 1), blurred and partially occluded pictures (Experiment 2) and coloured line drawings in visual noise (Experiment 3). Experiments 1 and 2 had an intentional study phase; the study phase of Experiment 3 was an incidental colour or category naming task. Changing colour from study to test always had negative effects on episodic recognition although colour was irrelevant. In contrast, in the matching task old pictures were generally matched faster than new ones independent of their colour congruence. In Experiment 3, an additional small advantage of congruent colours and of semantic processing occurred. We conclude that two different memory representations contribute to these tasks. Changes of an achromatic, more abstract representation, that is used in normal object recognition, and a representation of the specific exemplar that includes colour. This latter token is used in episodic recognition as well as in unusual perceptual tasks (Experiment 3).     

Interactions between visual working memory representations

We investigated whether the representations of different objects are maintained independently in working memory or interact with each other. Observers were shown two sequentially presented orientations and required to reproduce each orientation after a delay. The sequential presentation minimized perceptual interactions so that we could isolate interactions between memory representations per se. We found that similar orientations were repelled from each other whereas dissimilar orientations were attracted to each other. In addition, when one of the items was given greater attentional priority by means of a cue, the representation of the high-priority item was not influenced very much by the orientation of the low-priority item, but the representation of the low-priority item was strongly influenced by the orientation of the high-priority item. This indicates that attention modulates the interactions between working memory representations. In addition, errors in the reported orientations of the two objects were positively correlated under some conditions, suggesting that representations of distinct objects may become grouped together in memory. Together, these results demonstrate that working-memory representations are not independent but instead interact with each other in a manner that depends on attentional priority.