Global vs. local information processing in visual/spatial problem solving: The case of traveling salesman problem

Human visual/spatial problem solving often requires both global and local information to be processed. But the relationship between those two kinds of information and the way in which they interact with one another during problem solving has not been thoroughly discussed. In the particular setting of solving the traveling salesman problem (TSP), we investigated into the relative roles of global and local information processing. An experiment was conducted to measure the importance of global information and the possible constraints of global information processing on search. A model was built to simulate human TSP performance and was used to investigate further the relationship between global information processing and local information processing. Our model was compared with the human data we collected and with other models of human TSP solving.     

Does visual working memory work as a few fixed slots?

The present study investigated whether visual working memory (VWM) functions as a few (about 3?～ 4) fixed slots by examining how the distribution of VWM is adjusted. Adopting a change-detection paradigm, we required subjects to memorize four items, one of which was prioritized. If VWM functions as 3?～?4 slots, allocating multiple slots to the prioritized item would leave no slot for some other items; consequently no information would be stored for them, leading to a substantial decrease in change-detection performance no matter whether small or large changes occurred. The result showed that small changes on the unfavoured items were detected less accurately, indicating that more VWM was allocated to the favoured item. Yet meanwhile large changes that occurred on those unfavoured items could still be detected as well as those on the favoured one, indicating that each of them was still stored to some extent rather than completely discarded. The results suggested that VWM may not work as 3?～?4 fixed slots. Possible mechanisms were discussed based on the present results, including a modified slot model with more available slots, a continuous resource model, and a hierarchical model that assumes storage of ensemble information in addition to the information of individual items.     

Saccades elicit obligatory allocation of visual working memory

In daily life, visual working memory (VWM) typically works in contexts in which people make frequent saccades. Here, we investigated whether people can effectively control the allocation of VWM when making a saccade. Subjects were required to make an intervening saccade in the process of a memory task. The saccade target was either a to-be-remembered item or an extra, not-to-be-remembered item. The results showed that memory performance was poorer when a saccade was made to the extra, not-to-be-remembered item, regardless of its similarity to the memory item(s). In contrast, when memorizing the items while remaining fixated, subjects had similar memory performance whether an extra, not-to-be-remembered item was present or not. Taken together, these results demonstrated that volitional control over VWM allocation is greatly impaired when a saccade is made, indicating that VWM contains an automatic part that cooperates with eye movements and is allocated to a saccade target obligatorily.     

ICAT: a computational model for the adaptive control of fixation durations

Eye movements depend on cognitive processes related to visual information processing. Much has been learned about the spatial selection of fixation locations, while the principles governing the temporal control (fixation durations) are less clear. Here, we review current theories for the control of fixation durations in tasks like visual search, scanning, scene perception, and reading and propose a new model for the control of fixation durations. We distinguish two local principles from one global principle of control. First, an autonomous saccade timer initiates saccades after random time intervals (local-I). Second, foveal inhibition permits immediate prolongation of fixation durations by ongoing processing (local-II). Third, saccade timing is adaptive, so that the mean timer value depends on task requirements and fixation history (Global). We demonstrate by numerical simulations that our model qualitatively reproduces patterns of mean fixation durations and fixation duration distributions observed in typical experiments. When combined with assumptions of saccade target selection and oculomotor control, the model accounts for both temporal and spatial aspects of eye movement control in two versions of a visual search task. We conclude that the model provides a promising framework for the control of fixation durations in saccadic tasks.     

Visual working memory retains movement information within an allocentric reference frame

What frame of reference do we use to remember observed movements? One possibility is that visual working memory (VWM) retains movement information using a retinotopic frame of reference: A coordinate system with respect to the retina that retains view-dependent information. Alternatively, VWM might retain movement information using an allocentric frame of reference: A coordinate system with respect to the scene that retains view-invariant information. To address this question, I examined whether VWM retains view-dependent or view-invariant movement information. Results show that (1) observers have considerable difficulty remembering from which viewpoints they observed movements after a few seconds' delay, and (2) the same number of movements can be retained in VWM whether the movements are encoded and tested from the same viewpoint or from different viewpoints. Thus, movement representations contain little to no view-dependent information, which suggests that VWM uses an allocentric reference frame to retain movement information.     

眼睛运动如何与记忆相关？

很久以来,人们一直在致力于研究人的眼动与心理活动之间的关系,从而揭示其间的奥妙。众多研究表明,睡眠时的快速眼动（RapidEyeMovements,REM）及其周期对记忆的形成与巩固有重要作用。在清醒状态下,人的眼动就是为了获得视觉信息,如果涉及记忆任务,这就是编码阶段的具体行动。另外,问题解决过程也有眼动参与。总体看来,眼动和记忆之间是一种双向的关系,适当的眼动训练或许能够提高记忆成绩。     

Gesturing during mental problem solving reduces eye movements,especially for individuals with lower visual working memory capacity

Non-communicative hand gestures have been found to benefit problem-solving performance. These gestures seem to compensate for limited internal cognitive capacities, such as visual working memory capacity. Yet, it is not clear how gestures might perform this cognitive function. One hypothesis is that gesturing is a means to spatially index mental simulations, thereby reducing the need for visually projecting the mental simulation onto the visual presentation of the task. If that hypothesis is correct, less eye movements should be made when participants gesture during problem solving than when they do not gesture. We therefore used mobile eye tracking to investigate the effect of co-thought gesturing and visual working memory capacity on eye movements during mental solving of the Tower of Hanoi problem. Results revealed that gesturing indeed reduced the number of eye movements (lower saccade counts), especially for participants with a relatively lower visual working memory capacity. Subsequent problem-solving performance was not affected by having (not) gestured during the mental solving phase. The current findings suggest that our understanding of gestures in problem solving could be improved by taking into account eye movements during gesturing.     

Visual working memory supports the inhibition of previously processed information: evidence from preview search

In four experiments we assessed whether visual working memory (VWM) maintains a record of previously processed visual information, allowing old information to be inhibited, and new information to be prioritized. Specifically, we evaluated whether VWM contributes to the inhibition (i.e., visual marking) of previewed distractors in a preview search. We evaluated this proposal by testing three predictions. First, Experiments 1 and 2 demonstrate that preview inhibition is more effective when the number of previewed distractors is below VWM capacity than above; an effect that can only be observed at small preview set sizes (Experiment 2A) and when observers are allowed to move their eyes freely (Experiment 2B). Second, Experiment 3 shows that, when quantified as the number of inhibited distractors, the magnitude of the preview effect is stable across different search difficulties. Third, Experiment 4 demonstrates that individual differences in preview inhibition are correlated with individual differences in VWM capacity. These findings provide converging evidence that VWM supports the inhibition of previewed distractors. More generally, these findings demonstrate how VWM contributes to the efficiency of human visual information processing--VWM prioritizes new information by inhibiting old information from being reselected for attention.     

几何解题过程的眼动及视觉工作记忆模型:OGRE模型

简要介绍了一个几何解题过程的眼动及视觉工作记忆模型——跟动的几何推理引擎模型（OGRE）,对该模型的特点及其在其它认知过程中的应用进行了讨论。     

The contents of visual working memory reduce uncertainty during visual search

Information held in visual working memory (VWM) influences the allocation of attention during visual search, with targets matching the contents of VWM receiving processing benefits over those that do not. Such an effect could arise from multiple mechanisms: First, it is possible that the contents of working memory enhance the perceptual representation of the target. Alternatively, it is possible that when a target is presented among distractor items, the contents of working memory operate postperceptually to reduce uncertainty about the location of the target. In both cases, a match between the contents of VWM and the target should lead to facilitated processing. However, each effect makes distinct predictions regarding set-size manipulations; whereas perceptual enhancement accounts predict processing benefits regardless of set size, uncertainty reduction accounts predict benefits only with set sizes larger than 1, when there is uncertainty regarding the target location. In the present study, in which briefly presented, masked targets were presented in isolation, there was a negligible effect of the information held in VWM on target discrimination. However, in displays containing multiple masked items, information held in VWM strongly affected target discrimination. These results argue that working memory representations act at a postperceptual level to reduce uncertainty during visual search.     

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.     

基于空间方位信息的构型对视觉工作记忆绩效的影响

通过考察构成视觉客体构型的两种因素在视觉工作记忆任务中的影响, 探讨了构型对视觉工作记忆绩效的作用机制。采用变化觉察实验范式, 在构型朝向不变和旋转两种条件下, 系统地控制构型中的客体相对方位和整体几何形态两种因素的变化, 考察其对视觉工作记忆绩效的影响。实验结果显示, 无论构型朝向不变还是旋转, 只要客体相对方位保持一致, 工作记忆绩效就可以维持较高水平, 而几何形态没有表现出显著作用。上述发现提示构型客体相对方位是构型影响视觉工作记忆绩效的主要因素。     

The traveling salesman problem: A hierarchical model

Our review of prior literature on spatial information processing in perception, attention, and memory indicates that these cognitive functions involve similar mechanisms based on a hierarchical architecture. The present study extends the application of hierarchical models to the area of problem solving. First, we report results of an experiment in which human subjects were tested on a Euclidean traveling salesman problem (TSP) with 6 to 30 cities. The subject's solutions were either optimal or near-optimal in length and were produced in a time that was, on average, a linear function of the number of cities. Next, the performance of the subjects is compared with that of five representative artificial intelligence and operations research algorithms, that produce approximate solutions for Euclidean problems. None of these algorithms was found to be an adequate psychological model. Finally, we present a new algorithm for solving the TSP, which is based on a hierarchical pyramid architecture. The performance of this new algorithm is quite similar to the performance of the subjects.     

视觉工作记忆负载类型对注意选择的影响

通过操纵Flanker任务相对于视觉工作记忆任务的呈现位置, 探讨在视觉工作记忆编码和保持阶段, 精度负载和容量负载对注意选择的影响。行为结果发现, Flanker任务呈现位置和视觉工作记忆负载类型影响注意选择; ERP结果发现, 在保持阶段, 当搜索目标和干扰项不一致时, 负载类型影响N2成分。研究表明, 在编码阶段, 视觉工作记忆负载主要通过占用更多知觉资源降低干扰效应, 支持知觉负载理论; 而在保持阶段, 当Flanker任务位于记忆项内部时, 两类负载在工作记忆表征过程中不同的神经活动导致投入到注意选择的认知控制资源不同, 可能是两类负载影响保持阶段注意选择的机制。     

客体复杂度影响工作记忆可存储的客体数目

采用变化觉察范式,以对侧延迟活动（contralateral delay activity,CDA）的幅值为指标,通过操纵记忆刺激的复杂程度,对视觉工作记忆中可存储的客体数目（即工作记忆容量）问题进行了探讨。结果表明,2个复杂客体条件下的CDA幅值与4个复杂客体条件无显著差异,而4个简单客体条件的CDA幅值显著高于2个简单客体条件,即CDA的幅值受客体复杂度的调节。基于该结果推论：并非视觉工作记忆总能存储4个客体,其可存储的客体数目受客体复杂度影响。     

Beyond slots and resources: Grounding cognitive concepts in neural dynamics

Research over the past decade has suggested that the ability to hold information in visual working memory (VWM) may be limited to as few as three to four items. However, the precise nature and source of these capacity limits remains hotly debated. Most commonly, capacity limits have been inferred from studies of visual change detection, in which performance declines systematically as a function of the number of items that participants must remember. According to one view, such declines indicate that a limited number of fixed-resolution representations are held in independent memory “slots.” Another view suggests that such capacity limits are more apparent than real, but emerge as limited memory resources are distributed across more to-be-remembered items. Here we argue that, although both perspectives have merit and have generated and explained impressive amounts of empirical data, their central focus on the representations—rather than processes—underlying VWM may ultimately limit continuing progress in this area. As an alternative, we describe a neurally grounded, process-based approach to VWM: the dynamic field theory. Simulations demonstrate that this model can account for key aspects of behavioral performance in change detection, in addition to generating novel behavioral predictions that have been confirmed experimentally. Furthermore, we describe extensions of the model to recall tasks, the integration of visual features, cognitive development, individual differences, and functional imaging studies of VWM. We conclude by discussing the importance of grounding psychological concepts in neural dynamics, as a first step toward understanding the link between brain and behavior.     

数学解题过程的眼动研究

数学解题过程的眼动研究可划分为3个阶段：第一阶段是对数字运算过程的眼动研究,第二阶段是对数学应用题解题过程的眼动研究,第三阶段是对几何题解题过程的眼动研究。在我国,对数学解题过程的眼动研究尚为空白。加强这一领域的研究,可以深化对数学问题表征的认识,对数学学科的教与学具有重要意义。     

Intrinsic and extrinsic contributions to heavy tails in visual foraging

Eyes move over visual scenes to gather visual information. Studies have found heavy-tailed distributions in measures of eye movements during visual search, which raises questions about whether these distributions are pervasive to eye movements, and whether they arise from intrinsic or extrinsic factors. Three different measures of eye movement trajectories were examined during visual foraging of complex images, and all three were found to exhibit heavy tails: Spatial clustering of eye movements followed a power law distribution, saccade length distributions were lognormally distributed, and the speeds of slow, small amplitude movements occurring during fixations followed a 1/f spectral power law relation. Images were varied to test whether the spatial clustering of visual scene information is responsible for heavy tails in eye movements. Spatial clustering of eye movements and saccade length distributions were found to vary with image type and task demands, but no such effects were found for eye movement speeds during fixations. Results showed that heavy-tailed distributions are general and intrinsic to visual foraging, but some of them become aligned with visual stimuli when required by task demands. The potentially adaptive value of heavy-tailed distributions in visual foraging is discussed.     

Recognition of dance-like actions: Memory for static posture or dynamic movement?

Dance-like actions are complex visual stimuli involving multiple changes in body posture across time and space. Visual perception research has demonstrated a difference between the processing of dynamic body movement and the processing of static body posture. Yet, it is unclear whether this processing dissociation continues during the retention of body movement and body form in visual working memory (VWM). When observing a dance-like action, it is likely that static snapshot images of body posture will be retained alongside dynamic images of the complete motion. Therefore, we hypothesized that, as in perception, posture and movement would differ in VWM. Additionally, if body posture and body movement are separable in VWM, as form- and motion-based items, respectively, then differential interference from intervening form and motion tasks should occur during recognition. In two experiments, we examined these hypotheses. In Experiment 1, the recognition of postures and movements was tested in conditions in which the formats of the study and test stimuli matched (movement–study to movement–test, posture–study to posture–test) or mismatched (movement–study to posture–test, posture–study to movement–test). In Experiment 2, the recognition of postures and movements was compared after intervening form and motion tasks. These results indicated that (1) the recognition of body movement based only on posture is possible, but it is significantly poorer than recognition based on the entire movement stimulus, and (2) form-based interference does not impair memory for movements, although motion-based interference does. We concluded that, whereas static posture information is encoded during the observation of dance-like actions, body movement and body posture differ in VWM.