Processing dominance of global and local information in visual patterns

The processing dominance of global and local levels of visual patterns was studied using two tasks: speeded classification and identification. Stimuli were presented with spatial certainty and controlled eccentricity. The results with both procedures showed global advantage: RTs to global level were faster than those to local level. In the same way, the interference effect was bidirectional between the global and local levels, the amount of interference being larger from the global level to the local one than vice versa.     

Processing global information in briefly presented pictures

Summary The effect on object recognition of the processing of the global information in contextually coherent scenes was investigated in two experiments. In Experiment 1 subjects saw 100 ms presentations of line drawings containing objects that were either usual or unusual given the picture context. Following each exposure they were required to select from among four objects the one that had been contained in the scene. The consistency of the three distractor alternatives with the meaning of the picture was varied. Recognition accuracy was poor for unusual objects and when the distractors were consistent with the picture meaning and did not substantially differ from the performance of subjects who selected response alternatives after being provided with a theme of the picture, without actually viewing the pictures. This supports the conclusion that subjects were responding on the basis of the global information but not the local object information in the pictures. When the exposure duration was increased to 2 s (Experiment 2), processing of local information was apparent for both usual and unusual objects but effects of the global information were still evident.     

Emotional state and local versus global spatial memory

The present work investigated the effects of participant emotional state on global versus local memory for map-based information. Participants were placed into one of four emotion induction groups, crossing high and low arousal with positive and negative valence, or a control group. They then studied a university campus map and completed two memory tests, free recall and spatial statement verification. Converging evidence from these two tasks demonstrated that arousal amplifies symbolic distance effects and leads to a globally-focused spatial mental representation, partially at the expense of local knowledge. These results were found for both positively- and negatively-valenced affective states. The present study is the first investigation of emotional effects on spatial memory, and has implications for theories of emotion and spatial cognition.     

Processing load and memory for stereotype-based information

The present research considered the effects of stereotypes on judgmental and memorial processes. In particular, we investigated the heuristic utility of stereotype application in difficult or demanding information-processing contexts. Our results supported the prediction that stereotypical effects on memory are contingent upon the characteristics of the task environment. Whereas perceivers displayed preferential recall for stereotype-inconsistent information under low processing loads, this switched to a preference for consistent information as task demands increased. Likewise, target-based judgments were most stereotypic under high processing loads. Judgment-recall correlations supported the contention that, under high-loads, these inferences are related to the relative memorability of stereotypic information. We consider these findings in the wider context of stereotype-based effects on social cognition.     

Spatial frequency and selective attention to local and global information

Probe methods were used to investigate whether the distribution of attention to the local or the global structure of a stimulus affects the detectability of different spatial frequencies. Four experiments are reported in which the detectability of threshold probe gratings of different spatial frequencies was measured while subjects analyzed either the local or the global information from a display. A relative shift in the detectability of low and high frequencies was observed. Low frequencies were facilitated during global processing and/or high frequencies were facilitated during local processing.     

A variable mapping task produces symmetrical interference between global information and local information

When processing global and local aspects of compound visual figures, a robust finding is that global targets are detected faster and more accurately than local targets. Moreover, unidirectional interference is often observed. Despite the convincing evidence that global information and local information are available together, when attention is focused on the global level, items from the local level often have very little, if any, effect on behavior. If local information is available with global information, then why is global dominance so often observed under such a wide range of conditions? This paper is concerned with the fate of the ignored, and apparently ineffective, local distractors. In our experiments, at least one critical factor was stimulus-response (S-R) mapping. We compared a consistent S-R task, which facilitated a speed advantage for global, with a variable S-R task, which required a higher degree of semantic analysis for each stimulus. The two tasks produced large differences in behavior, showing unidirectional interference in the consistent S-R task, and strong bidirectional interference in the variable S-R task. Thus, the identity of ignored local distractors was available, even under conditions that favored focused attention to global information. The results provide support for a model in which global processing proceeds more quickly at early perceptual stages and in which local processing can catch up if processing demands are increased at later stages.     

抑郁症患者工作记忆内情绪刺激加工的特点及其机制

抑郁症患者在工作记忆内情绪刺激加工的特点为倾向于加工与负性心境一致的材料, 被认为是抑郁症认知易感性的核心特征。目前研究者们围绕抑郁症工作记忆中央执行系统三个子功能的情绪刺激加工特点及其作用机制进行了大量研究, 发现在更新功能上, 患者难以移除负性情绪信息, 且在正性信息的加工上存在缺损; 在抑制功能上, 患者难以抑制无关负性情绪信息进入工作记忆; 在转换功能上, 患者情绪材料转换困难的研究证据尚不充分。神经生理与脑成像的研究初步表明, 工作记忆中的情绪刺激加工与抑郁症患者背外侧前额叶和前扣带回的功能激活水平异常有关。未来研究需评估工作记忆三个子功能对抑郁症状的差异性贡献及在情绪刺激加工上的统一性, 并探究其随疾病发生发展变化的轨迹, 谨慎选取并评估不同情绪刺激材料指标的诱发效应及其对工作记忆功能的独特影响。在此基础上, 深入探究工作记忆内情绪刺激加工的神经机制, 为工作记忆偏向矫正干预的临床应用及其预期效果提供理论依据和方向。     

Visual working memory for global,object, and part-based information

We investigated visual working memory for novel objects and parts of novel objects. After a delay period, participants showed strikingly more accurate performance recognizing a single whole object than the parts of that object. This bias to remember whole objects, rather than parts, persisted even when the division between parts was clearly defined and the parts were disconnected from each other so that, in order to remember the single whole object, the participants needed to mentally combine the parts. In addition, the bias was confirmed when the parts were divided by color. These experiments indicated that holistic perceptual-grouping biases are automatically used to organize storage in visual working memory. In addition, our results suggested that the bias was impervious to top-down consciously directed control, because when task demands were manipulated through instruction and catch trials, the participants still recognized whole objects more quickly and more accurately than their parts. This bias persisted even when the whole objects were novel and the parts were familiar. We propose that visual working memory representations depend primarily on the global configural properties of whole objects, rather than part-based representations, even when the parts themselves can be clearly perceived as individual objects. This global configural bias beneficially reduces memory load on a capacity-limited system operating in a complex visual environment, because fewer distinct items must be remembered.     

On the role of global and local visual information in goal-directed walking.

The aim of the present study was to determine what interactions occur between the visual information available to walking subjects in the global optical flow and those of a more local nature relating to the dilation rate of a target on the retina. A goal-directed walking task was used in which thirteen subjects were asked to stop spontaneously as near as possible to a stationary target. The experiment was carried out in a special room, by means of a texture flow generator with which the velocity and direction of the optical flow arising from the ground were varied. Twelve experimental conditions were tested, involving various combinations of target size and texture velocity. The results show that with both of the targets, modifications to the global flow significantly affected the subjects' performances (walking speed and time-to-contact with the target upon braking) in the fast-approaching texture situation, but not in the receding or slowly-approaching situations. The results are discussed as to what they reveal about the visual strategies used by an actively moving observer to anticipate a collision with a stationary target.     

Processing of temporal duration information in working memory after frontodorsal tumour excisions

This study aimed to test the hypothesis that impairments of temporal duration processing after frontal lobe lesions reflect deficits in executive monitoring functions rather than a domain-specific deficit in the maintenance of duration information in working memory. Patients with frontodorsal lesions, clinical controls with post-central lesions, and healthy controls performed recognition and classification tasks, which should allow for testing maintenance and monitoring functions, respectively. Results showed mild non-selective impairments of the frontal patients on both temporal and spatial recognition tasks, but a marked selective degradation on temporal classification while performance on spatial classification was unimpaired. This suggests that maintenance of duration information in working memory after frontal lesions is basically preserved but that, depending on executive task characteristics, there is a specific deficit in the strategic organization of this type of information.     

Functional hemispheric differences for the categorization of global and local information in naturalistic stimuli

Up to now functional hemispheric asymmetries for global/local processing have mainly been investigated with hierarchical letters as stimuli. In the present study, three experiments were conducted to examine whether corresponding visual-field (VF) effects can also be obtained with more naturalistic stimuli. To this end, images of animals with a pattern placed on their body were displayed as stimuli. The task for the global level and for the local level was to categorize the animals and the patterns, respectively. As a result, VF-effects were also found for these stimuli and tasks. It is concluded that the hemispheric differences observed for hierarchical letters also hold for naturalistic stimuli.     

Time course of item and associative information: implications for global memory models

The time course of availability of associative and item information was examined by using a response signal procedure. Associative information discriminates between a studied pair of words and a pair with words from two different studied pairs. Item information is sufficient to discriminate between a studied pair and a pair not studied. In two experiments, discriminations that require associative information are delayed relative to those based on item information. Two additional experiments discount alternative explanations in terms of the time to encode the test items or task strategies. Examination of the global memory models of Gillund and Shiffrin (1984), Hintzman (1988), and Murdock (1982) shows that the models treat item and associative information inseparably. Modifications to these models which can produce separate contributions for item and associative information do not predict any difference in their availability. Two possible mechanisms for the delayed availability of associative information are considered: the involvement of recall in recognition and the time required to form a compound cue.     

Testing a queue hypothesis for the processing of global and local information.

To test whether the advantage for global features in visual perception is stationary throughout the course of processing or is superseded by a local advantage, 6 experiments were conducted in which subjects responded to auditorially presented letter names, while viewing compound visual stimuli. The consistencies of the 2 levels of the compound letters with the auditory stimuli were varied. The requirement with respect to the visual stimulus was manipulated between experiments. The onset asynchrony (SOA) between the visual stimulus and the auditory one was randomized within blocks. Interaction of SOA with consistency of either of the globality levels with the auditory stimulus would indicate lack of stationarity. No such indication was found. Several findings suggest global advantage. The results hold across 3 exposure durations. Findings support the hypothesis of global precedence as well as the claim that it is stationary.     

Effects of exposure duration and eccentricity of global and local information on processing dominance

Abstract

The effects of exposure duration of stimuli and the eccentricity of local and global information in hierarchical patterns on processing dominance were examined using a paradigm of selective attention and masked stimuli. In the first experiment, the aim was to determine whether the exposure duration of stimuli has differential effects on processing dominance. Stimuli were presented with spatial certainty and controlled eccentricity at four exposure durations (unlimited, 140 msec, 70 msec and 40 msec). The results showed global advantage independently of the exposure duration used. Differential effects were obtained in relation to the interference between the global and local levels depending on the exposure duration. The purpose of the second and third experiments was to determine whether the eccentricity of local and global levels affects processing dominance under a condition of brief exposure duration of stimuli. The results of Experiment 2 showed local dominance when the eccentricity was different for both levels and biased to the local level (H's and S's stimuli). On the contrary, they showed global dominance when the eccentricity of the two levels was the same (C's stimuli). The results of Experiment 3 revealed that the effect of global dominance persisted when the stimuli presented local and global information foveally.     

Efficient filtering of irrelevant global and local information when target level and location are random

Summary Using compound letter stimuli (Navon, 1977), Paquet and Merikle (1988) found that subjects are very good at ignoring distractor letters shown in an irrelevant location when the distractors are also shown at the level of the structure opposite to that of the target. However, the procedure used by Paquet and Merikle (1988) might have biassed the results toward showing relatively poor non-target processing in this instance. The target level of structure was a blocked variable, and so subjects could ignore the other level of structure completely. In the present experiment, the target level was either blocked, requiring focussed attention to one level of structure, or else it varied randomly from trial to trial. This latter condition should require attention to be allocated to both levels of structure. Results were the same in both cases, namely efficient filtering of nontarget information when it was not at the target level of structure. The results are related to proposals (Duncan, 1981; Van der Heijden, 1981) that semantic analysis of visual information is an unlimited-capacity process.     

Attending to the big picture: mood and global versus local processing of visual information

Two experiments employed image-based tasks to test the hypothesis that happier moods promote a greater focus on the forest and sadder moods a greater focus on the trees. The hypothesis was based on the idea that in task situations, affective cues may be experienced as task-relevant information, which then influences global versus local attention. Using a serial-reproduction paradigm, Experiment 1 showed that individuals in sad moods were less likely than those in happier moods to use an accessible global concept to guide attempts to reproduce a drawing from memory. Experiment 2 investigated the same hypothesis by assessing the use of global and local attributes to classify geometric figures. As predicted, individuals in sad moods were less likely than those in happier moods to classify figures on the basis of global features.     

Distinctiveness models of memory and absolute identification: evidence for local, not global, effects

Many models of memory assume that the probability of remembering an item is related to how distinctive that item is relative to all the other items in the set, with no distinction made between the contributions of near or far items. These “global” distinctiveness models do well in accounting for the ubiquitous serial position effects observed in numerous memory paradigms, including absolute identification. Here, we provide experimental confirmation of Bower's (1971) suggestion that, contrary to a fundamental prediction of global distinctiveness models, midseries items can be more discriminable than their immediate neighbours. We show that such data are consistent with a revised distinctiveness account in which the factor affecting discrimination performance is primarily the distinctiveness of an item relative to its close neighbours.