空间工作记忆负载对真实场景情境提示效应的影响

重复的画面布局能够促进观察者对目标项的搜索 (情境提示效应)。本研究采用双任务范式,分别在视觉搜索任务的学习阶段 (实验2a) 和测验阶段 (实验2b) 加入空间工作记忆任务, 并与单任务基线 (实验1)进行比较, 考察空间工作记忆负载对真实场景搜索中情境线索学习和情境提示效应表达的影响。结果发现: 空间负载会增大学习阶段的情境提示效应量, 同时削弱测验阶段的情境提示效应量, 而不影响情境线索的外显提取。由此可见, 真实场景中情境线索的学习和提示效应的表达均会受到有限的工作记忆资源的影响, 但情境线索提取的外显性不变。     

Working memory dependence of spatial contextual cueing for visual search

When spatial stimulus configurations repeat in visual search, a search facilitation, resulting in shorter search times, can be observed that is due to incidental learning. This contextual cueing effect appears to be rather implicit, uncorrelated with observers’ explicit memory of display configurations. Nevertheless, as I review here, this search facilitation due to contextual cueing depends on visuospatial working memory resources, and it disappears when visuospatial working memory is loaded by a concurrent delayed match to sample task. However, the search facilitation immediately recovers for displays learnt under visuospatial working memory load when this load is removed in a subsequent test phase. Thus, latent learning of visuospatial configurations does not depend on visuospatial working memory, but the expression of learning, as memory‐guided search in repeated displays, does. This working memory dependence has also consequences for visual search with foveal vision loss, where top‐down controlled visual exploration strategies pose high demands on visuospatial working memory, in this way interfering with memory‐guided search in repeated displays. Converging evidence for the contribution of working memory to contextual cueing comes from neuroimaging data demonstrating that distinct cortical areas along the intraparietal sulcus as well as more ventral parieto‐occipital cortex are jointly activated by visual working memory and contextual cueing.     

The role of spatial working memory in visual search efficiency

Many theories have proposed that visual working memory plays an important role in visual search. In contrast, by showing that a nonspatial working memory load did not interfere with search efficiency, Woodman, Vogel, and Luck (2001) recently proposed that the role of working memory in visual search is insignificant. However, the visual search process may interfere with spatial working memory. In the present study, a visual search task was performed concurrently with either a spatial working memory task (Experiment 1) or a nonspatial working memory task (Experiment 2). We found that the visual search process interfered with a spatial working memory load, but not with a nonspatial working memory load. These results suggest that there is a distinction between spatial and nonspatial working memory in terms of interactions with visual search tasks. These results imply that the visual search process and spatial working memory storage require the same limited-capacity mechanisms.     

Spatial working memory load affects counting but not subitizing in enumeration

The present study investigated whether subitizing reflects capacity limitations associated with two types of working memory tasks. Under a dual-task situation, participants performed an enumeration task in conjunction with either a spatial (Experiment 1) or a nonspatial visual (Experiment 2) working memory task. Experiment 1 showed that spatial working memory load affected the slope of a counting function but did not affect subitizing performance or subitizing range. Experiment 2 showed that nonspatial visual working memory load affected neither enumeration efficiency nor subitizing range. Furthermore, in both spatial and nonspatial memory tasks, neither subitizing efficiency nor subitizing range was affected by amount of imposed memory load. In all the experiments, working memory load failed to influence slope, subitizing range, or overall reaction time. These findings suggest that subitizing is performed without either spatial or nonspatial working memory. A possible mechanism of subitizing with independent capacity of working memory is discussed.     

The effect of spatial and nonspatial contextual information on visual object memory

Recent research has found visual object memory can be stored as part of a larger scene representation rather than independently of scene context. The present study examined how spatial and nonspatial contextual information modulate visual object memory. Two experiments tested participants’ visual memory by using a change detection task in which a target object's orientation was either the same as it appeared during initial viewing or changed. In addition, we examined the effect of spatial and nonspatial contextual manipulations on change detection performance. The results revealed that visual object representations can be maintained reliably after viewing arrays of objects. Moreover, change detection performance was significantly higher when either spatial or nonspatial contextual information remained the same in the test image. We concluded that while processing complex visual stimuli such as object arrays, visual object memory can be stored as part of a comprehensive scene representation, and both spatial and nonspatial contextual changes modulate visual memory retrieval and comparison.     

The role of memory representation in the vigilance decrement

Working memory load is critically important for the overall level of performance on vigilance tasks. However, its role in a key aspect of vigilance—sensitivity decrement over time—is unclear. We used a dual-task procedure in which either a spatial or a nonspatial working memory task was performed simultaneously with a spatial vigilance task for 20 min. Sensitivity in the vigilance task declined over time when the concurrent task involved spatial working memory. In contrast, there was no sensitivity decrement with a nonspatial working memory task. The results provide the first evidence of a specific role for working memory representation in vigilance decrement. The findings are also consistent with a multiple resource theory in which separate resources for memory representation and cognitive control operations are differentially susceptible to depletion over time, depending on the demands of the task at hand.     

视空工作记忆负载对真实场景搜索绩效的影响

采用视空工作记忆任务和真实场景搜索任务相结合的双任务范式, 结合眼动技术将搜索过程划分为起始阶段、扫描阶段和确认阶段, 探究视空工作记忆负载对真实场景搜索绩效的影响机制, 同时考查试次间搜索目标是否变化、目标模板的具体化程度以及搜索场景画面的视觉混乱度所起的调节作用。结果表明, 视空工作记忆负载会降低真实场景搜索的成绩, 在搜索过程中表现为视空负载条件下扫描阶段持续时间的延长、注视点数目的增加和空间负载条件下确认阶段持续时间的延长, 视空负载对搜索过程的影响与目标模板的具体化程度有关; 空间负载会降低真实场景搜索的效率, 且与搜索画面的视觉混乱度有关, 而客体负载则不会。由此可见, 视空工作记忆负载对真实场景搜索绩效的影响不同, 空间负载对搜索过程的影响比客体负载更长久, 二者均受到目标模板具体化程度的调节; 仅空间负载会降低真实场景的搜索效率, 且受到搜索场景画面视觉混乱度的调节。     

Visuelle und räumliche Interferenzen beim Schlußfolgern

The present paper provides evidence for a differential involvement of spatial and visual mental resources in propositional and spatial reasoning. Two experiments consider the load on visuospatial working memory during reasoning. Subjects solve propositional and spatial reasoning tasks either alone or in combination with visual tracking. In the first experiment, subjects resource allocation strategy is manipulated. Independently of the allocation of mental resources to the reasoning tasks or the tracking task, tracking is found to interfere much more with spatial than with propositional reasoning. In the second experiment, propositional reasoning after a comprehension training is disrupted by a simultaneous secondary spatial task, but not by the visual tracking task.     

工作记忆与知觉负载对工作记忆表征引导注意的调节

本研究采用4个眼动实验探讨不同知觉负载条件下的视觉搜索任务中工作记忆负载对基于工作记忆表征的注意引导效应的影响。实验1和实验3采用低知觉负载的视觉搜索任务,结果在视觉工作记忆负载为1和2时观察到了显著的注意引导效应,但当负载增加到4时注意引导效应消失了;实验2和实验4采用高知觉负载的视觉搜索任务,结果发现注意引导效应在工作记忆负载增加到2时就已经消失了。上述结果表明:工作记忆负载和知觉负载都能够通过调控认知资源的方式来影响工作记忆表征对注意的引导,当认知资源充足时,工作记忆能够同时保持多个记忆表征对视觉注意的引导。     

Visuospatial working memory and mental representation of spatial descriptions

The purpose of the present research is to investigate whether different components of working memory (WM) are involved in processing spatial and nonspatial texts. The interference effects of two concurrent tasks on comprehension and recall of two kinds of text were investigated in two experiments. Each participant listened to a spatial and a nonspatial text, with one of two concurrent tasks: articulatory suppression or spatial tapping. The dependent variables in Experiment 1 were accuracy of recall and verification of information inferred from the texts. In Experiment 2 response times in the verification task were also considered. Results support the hypothesis that verbal and spatial components of working memory are differentially involved in the comprehension and memory of spatial and nonspatial texts, with a selective interference effect of the spatial concurrent task on the spatial text and an interference effect of the verbal concurrent task on both the spatial and nonspatial texts. These effects emerged for recall, sentence verification, and response times. Our findings confirm previous results showing that the verbal component of working memory is involved in the process of text comprehension and memory. In addition, they show that visuospatial working memory is involved, in so far as the text conveys visuospatial information.     

The impact of working memory load on task execution and online plan adjustment during multitasking in a virtual environment

Three experiments investigated the impact of working memory load on online plan adjustment during a test of multitasking in young, nonexpert, adult participants. Multitasking was assessed using the Edinburgh Virtual Errands Test (EVET). Participants were asked to memorize either good or poor plans for performing multiple errands and were assessed both on task completion and on the extent to which they modified their plans during EVET performance. EVET was performed twice, with and without a secondary task loading a component of working memory. In Experiment 1, articulatory suppression was used to load the phonological loop. In Experiment 2, oral random generation was used to load executive functions. In Experiment 3, spatial working memory was loaded with an auditory spatial localization task. EVET performance for both good- and poor-planning groups was disrupted by random generation and sound localization, but not by articulatory suppression. Additionally, people given a poor plan were able to overcome this initial disadvantage by modifying their plans online. It was concluded that, in addition to executive functions, multiple errands performance draws heavily on spatial, but not verbal, working memory resources but can be successfully completed on the basis of modifying plans online, despite a secondary task load.     

The boundary conditions of priming of visual search: From passive viewing through task-relevant working memory load

Priming of visual search has a dominating effect upon attentional shifts and is thought to play a decisive role in visual stability. Despite this importance, the nature of the memory underlying priming remains controversial. To understand more fully the necessary conditions for priming, we contrasted passive versus active viewing of visual search arrays. There was no priming from passive viewing of search arrays, while it was strong for active search of the same displays. Displays requiring no search resulted in no priming, again showing that search is needed for priming to occur. Finally, we introduced working memory load during visual search in an effort to disrupt priming. The memorized items had either the same colors as or different colors from the visual search items. Retaining items in working memory inhibited priming of the working memory task-relevant colors, while little interference was observed for unrelated colors. The picture that emerges of priming is that it requires active attentional processing of the search items in addition to the operation of visual working memory, where the task relevance of the working memory load plays a key role.     

Implicit,long-term spatial contextual memory

Learning and memory of novel spatial configurations aids behaviors such as visual search through an implicit process called contextual cuing (M. M. Chun & Y. Jiang, 1998). The present study provides rigorous tests of the implicit nature ofcontextual cuing. Experiment 1 used a recognition test that closely matched the learning task, confirming that memory traces of predictive spatial context were not accessible to conscious retrieval. Experiment 2 gave explicit instructions to encode visual context during learning, but learning was not improved and conscious memory remained undetectable. Experiment 3 illustrates that memory traces for spatial context may persist for at least 1 week, suggesting along-term component of contextual cuing. These experiments indicate that the learning and memory of spatial context in the contextual cuing task are indeed implicit. The results have implications for understanding the neural substrate of spatial contextual learning, which may depend on an intact medial temporal lobe system that includes the hippocampus (Mi. M. Chun & E. A. Phelps, 1999).     

Allocentric spatial learning by hippocampectomised rats: A further test of the “spatial mapping” and “working memory” theories of hippocampal function

This paper reports a series of three experiments that tested the “spatial-mapping” and “working-memory” theories of hippocampal function. The experimental designs incorporate separate reference- and working-memory procedures of a water-escape task, using both spatial and non-spatial learning. In Experiment 1 (Reference memory), rats with hippocampal (HC) or cortical (CC) lesions and unoperated (UNOP) rats learned to swim to a rigid visible escape platform while avoiding contact with a floating one. In the nonspatial task, the platforms each occupied any of 8 possible positions in the pool over successive trials but differed in appearance. In the spatial task, the platforms were of identical appearance but the safe one always occupied a single fixed location. The HC rats showed a highly specific spatial learning impairment but did learn to perform consistently above chance towards the end of training. In Experiment 2 (working memory), new groups of rats were trained on similar spatial and nonspatial tasks, but the platform designated correct-in terms of its visual appearance or its spatial location-was randomly changed each day. No animal learned the nonspatial task despite extensive training. Performance on the spatial version unexpectedly revealed an impairment in the CC as well as the HC group relative to the UNOP rats. However, the HCs again performed at above chance levels and demonstrated rapid (I-trial) spatial learning towards the end training. Experiment 3 used a place navigation matching-to-sample task examine spatial working memory further. Each day, an underwater platform was hidden at any of 4 possible locations, and the rats were given 2 trials to search for it. Both UNOP and CC rats located the platform faster on Trial 2 than on Trial 1, even when the inter-trial interval was long as 30min. HC rats were no faster on Trial 2 than on Trial 1. We conclude that hippocampal lesions (1) severely but partially impair spatial but not visual reference memory and (2) give rise to different patterns impairment in different working-mermory tasks. The results are a chal lenge to both the spatial-mapping and working-memory theories.     

Picture span test: Measuring visual working memory capacity involved in remembering and comprehension

The working memory system is assumed to operate with domain-specific (verbal and visuospatial) resources that support cognitive activities. However, in research on visuospatial working memory, an appropriate visual working memory task has not been established. For the present study, a novel task was developed: the picture span test (PST). This test requires memorizing parts of scene images while comprehending various scene situations simultaneously. Results of correlation analyses and a factor analysis among college students (n=52) validated that PST can predict visuospatial cognitive skills whereas a simple visual storage task and a verbal working memory task cannot. Furthermore, an error analysis indicated that inhibition is important for visuospatial working memory. Additionally, PST is considered to reflect individual differences in the visual working memory capacity. These findings suggest that the PST is appropriate for measuring visual working memory capacity and can elucidate its relationship to higher cognition.     

Ensemble coding remains accurate under object and spatial visual working memory load

A number of studies have provided evidence that the visual system statistically summarizes large amounts of information that would exceed the limitations of attention and working memory (ensemble coding). However the necessity of working memory resources for ensemble coding has not yet been tested directly. In the current study, we used a dual task design to test the effect of object and spatial visual working memory load on size averaging accuracy. In Experiment 1, we tested participants’ accuracy in comparing the mean size of two sets under various levels of object visual working memory load. Although the accuracy of average size judgments depended on the difference in mean size between the two sets, we found no effect of working memory load. In Experiment 2, we tested the same average size judgment while participants were under spatial visual working memory load, again finding no effect of load on averaging accuracy. Overall our results reveal that ensemble coding can proceed unimpeded and highly accurately under both object and spatial visual working memory load, providing further evidence that ensemble coding reflects a basic perceptual process distinct from that of individual object processing.     

Visual Search Remains Efficient When Visual Working Memory is Full

Many theories of attention have proposed that visual working memory plays an important role in visual search tasks. The present study examined the involvement of visual working memory in search using a dual-task paradigm in which participants performed a visual search task while maintaining no, two, or four objects in visual working memory. The presence of a working memory load added a constant delay to the visual search reaction times, irrespective of the number of items in the visual search array. That is, there was no change in the slope of the function relating reaction time to the number of items in the search array, indicating that the search process itself was not slowed by the memory load. Moreover, the search task did not substantially impair the maintenance of information in visual working memory. These results suggest that visual search requires minimal visual working memory resources, a conclusion that is inconsistent with theories that propose a close link between attention and working memory.     

Visual working memory load disrupts the space‐based attentional guidance of target selection

During visual search, the selection of target objects is guided by stored representations of target‐defining features (attentional templates). It is commonly believed that such templates are maintained in visual working memory (WM), but empirical evidence for this assumption remains inconclusive. Here, we tested whether retaining non‐spatial object features (shapes) in WM interferes with attentional target selection processes in a concurrent search task that required spatial templates for target locations. Participants memorized one shape (low WM load) or four shapes (high WM load) in a sample display during a retention period. On some trials, they matched them to a subsequent memory test display. On other trials, a search display including two lateral bars in the upper or lower visual field was presented instead, and participants reported the orientation of target bars that were defined by their location (e.g., upper left or lower right). To assess the efficiency of attentional control under low and high WM load, EEG was recorded and the N2pc was measured as a marker of attentional target selection. Target N2pc components were strongly delayed when concurrent WM load was high, indicating that holding multiple object shapes in WM competes with the simultaneous retention of spatial attentional templates for target locations. These observations provide new electrophysiological evidence that such templates are maintained in WM, and also challenge suggestions that spatial and non‐spatial contents are represented in separate independent visual WM stores.     

The effect of working memory load on the SNARC effect: Maybe tasks have a word to say

We investigated the effect of working memory load on the SNARC (spatial–numerical association of response codes) effect under different number judgment tasks (parity judgment and magnitude comparison), using a novel dual task. Instead of exerting load over the whole block of number judgment trials, in this dual task, number judgment trials were inserted into each interstimulus interval of an n-back task, which served as the working memory load. We varied both load type (verbal and spatial) and amount (1-load, 2-load, and 3-load). The results indicated that the SNARC effect disappeared even under the 1-load condition for a parity judgment, regardless of the type of load. However, during the magnitude comparison task, the SNARC effect increased with increasing load amounts under spatial load conditions; under verbal load conditions, the SNARC effect decreased with increasing amounts of load, and disappeared during the 3-load task. The difference between the parity and magnitude tasks was not attributable to the interval stimuli or task switching. These findings confirm that different spatial–numerical associations for comparing numerical magnitudes and judgments of parity have different needs with respect to working memory resources.