Global and local precedence: selective attention in form and motion perception

This study explores the perception of stimuli at two levels: local parts and the wholes that comprise these parts. Previous research has produced contradictory results. Some studies (e.g., Pomerantz & Sager, 1975) show local precedence, in which the local parts are more difficult to ignore in selective attention tasks. Other studies (e.g., Navon, 1977) have shown the opposite effect, global precedence. The present five experiments trace the causes of this discrepancy by exploring the effects of the relative discriminabilities of the local and global levels of the stimuli and the differences between two different measures of selective attention, namely, Stroop-type interference (attributable to incongruity on the irrelevant dimension) and Garner-type interference (attributable to variability on the irrelevant dimension). The experiments also examine whether the precedence effects previously examined in form perception generalize to motion perception. The results show that (a) some cases of global precedence are due solely to the greater perceptual discriminability of the global level and thus demonstrate only that more discriminable stimuli are harder to ignore; (b) instances of both local and global precedence can be demonstrated for certain types of stimuli, even when the discriminabilities of their local and global levels have been equated; and (c) the Stroop and Garner measures of selective attention are not equivalent but instead measure different types of interference. In addition, a distinction is made between two fundamentally different types of part-whole relationships that exist in visual configurations, one based only on the positions of the parts (Type P) and one based also on the nature of the parts (Type N). Previous research has focused on Type P, which appears to be irrelevant to the broader questions of Gestalt and top-down effects in perception. It is concluded that bona fide cases of both local and global precedence have been amply documented but that no general theory can account for why or when these effects will appear until we better understand both the nature of part-whole relationships and the perceptual processes that are tapped by different measures of selective attention.     

封闭性知觉在大范围优先性中的特殊性

本文研究当封闭性作为被试分辨的图形性质时,空间位置不确定性和视野位置对大范围优先性有何影响。实验发现：（１）无论复合刺激呈现在视野的中央或外周．分辨复合刺激的整体性质的反应时（ＲＴ）比分辨局部性质的ＲＴ短,整体性质对分辨局部性质的反应有较强的干扰作用。相反,局部性质对分辨整体性质的反应的影响较小;（２）刺激位置的不确定对大范围优先性没有显著影响;（３）与周边刺激相比,分辨视野中央的复合刺激的ＲＴ较短,但整体性质的ＲＴ优势和对局部性质的干扰作用,不受刺激在视野中的位置的影响。这些实验结果揭示了封闭性知觉在大范围优先性中的特殊性。     

Global predominance in object recognition: artefact or treatment rule?

This paper provides a critical evaluation of the idea that, relative to the identity of the parts (local aspect), the configuration of the parts (global aspect) is of special importance during perceptual analysis. The controversy surrounding the global precedence phenomenon (Navon, 1977) is reviewed. In particular, I evaluate and reject the hypothesis that global precedence is simply the product of the greater discriminability of the global aspect. Instead, I propose that one general rule characterizing preattentive perceptual processing is a broad categorization of global information. I present the empirical evidence supporting this model and suggest some direction for future studies.     

Does aging affect the allocation of visual attention in global and local information processing?

The earliest studies of Navon (1977) showed that in certain conditions the visual perception of hierarchical stimuli generates a global precedence effect. This hypothesis is based on the joint occurrence of two effects: a response time (RT) advantage for identifying global targets and interference by global distractors when responding to a local target. The aim of the present study was to determine the involvement of attentional mechanisms and whether certain aspects are specifically altered by normal aging. In a selective-attention task, a complete global precedence effect was found for young and old subjects. However, for the old subjects, global interference on local identification was more pronounced than for the young subjects. In a divided-attention task, the RT advantage was affected by attention shifts between global and local forms for both young and old subjects, but the global interference effect did not change.     

Forest before trees? It depends where you look

Because it may be deduced from the more elementary principles of visual processing, global precedence (Navon, 1977) is not a primary perceptual principle. Subjects were presented with a large letter made out of small ones and asked to make an identification response on the basis of either the large or small letter. When fixation was controlled to provide adequate stimulation from the small letter, there was no difference in reaction time (RT) between the large and small targets. Also, there was no difference in interference due to response incompatibility of the unattended letter based on target size. However, when the stimulus was presented peripherally, unpredictably to the right or left of fixation, RT was faster to the large target and interference was substantially greater for the small target. Functions for the development of associative strength and associative interference are presented. Global precedence is dependent on factors tending to degrade small stimuli more than large ones.     

Gobal-local precedence in picture processing

Summary Previous investigations of the global precedence hypothesis (Navon, 1977) have utilized compound letter stimuli. In these stimuli there is no predictive relationship between the global and local levels. Pictorial stimuli, however, contain mutually predictable global and local levels. This study investigated the global precedence hypothesis with pictorial stimuli using a Stroop-like interference task similar to that used by Navon. Subjects were required to respond either to the global (e.g., beach or farm) or local (e.g., boat or tractor) level of a scene. The display size and consistency of the global and local levels were varied. Response latencies supported global precedence for small scenes (4°) but local precedence for large scenes (16°). The results are interpreted by a model in which the priority of processing is determined by a critical spatial frequency sampling bandwidth.Portions of this research were presented at the meeting of the Psychonomic Society, Minneapolis, November, 1982. The authors with to express their sincere appreciation to Tom Petros for his assistance in data analysis. Requests for reprints should be addressed to James R. Antes, Department of Psychology, University of North Dakota, Grand Forks, ND 58202.     

Do response time advantage and interference reflect the order of processing of global- and local-level information?

Navon's (1977) global precedence hypothesis was based primarily on the joint occurrence of two effects: a response time (RT) advantage for identifying global targets, and interference by global distractors on responding to local targets. Although the hypothesis has been questioned on the basis of experiments in which it has been shown that a local RT advantage and local interference can occur, it is still frequently assumed that these two effects are a valid measure of the order in which local and global levels of structure are processed. In the present experiment, this assumption was examined. Subjects identified target letters that occurred randomly at the global or local level in a divided-attention task. The visual angle subtended by the stimulus pattern was varied, a manipulation known to affect the relative speed of response to local- or global-level information. Local targets were identified faster than global targets at the larger visual angles, but there was no difference in RT at the smallest visual angle. Despite this change in RT advantage, the interference effect did not change as a function of the visual angle of the stimulus pattern. Moreover, global distractors interfered with responding to local targets but local targets had no effect on responding to global targets, which is exactly the opposite of the finding one would expect if RT advantage and interference reflected order of processing. These findings are not consistent with the assumption that RT advantage and interference reflect order of processing in a simple way.     

The role of spatial frequency in the processing of hierarchically organized stimuli

Can spatial frequency differences between local and global forms account for differences in the way different levels of structure are analyzed? We examined this question by having subjects identify local or global forms of hierarchical stimuli that had beencontrast balanced. Contrast balancing eliminates low spatial frequencies, so that both local and global forms must be identified on the basis of high spatial frequency information. Response times (RTs) to global (but not local) forms were slowed for contrast-balanced stimuli, suggesting that low spatial frequencies mediate the global RT advantage typically found. In contrast, interference between local and global forms was little affected by contrast balancing or by shifts of attention between local and global forms, suggesting that it does not result from inhibitory interactions between spatial frequency channels or from temporal precedence of low versus high spatial frequency information. Finally, shifts of attention between local and global forms were also little affected by contrast balancing, suggesting that they were not based on spatial frequency.     

Do the global advantage and interference effects covary?

The global precedence hypothesis has been operationally defined as a faster or earlier processing of the global than of the local properties of an image (global advantage) and as interference by processing at the global level with processing at the local level (global interference). Navon (1977) proposed an association between the global advantage and interference effects. Other studies have shown a dissociation between the two effects (e.g., Lamb & Robertson, 1988). It seems that the controversy in previous research resulted from not equalizing the eccentricities of global and local properties. In the present study, the eccentricities of the two levels were equalized by using stimuli with all their elements located along their perimeters. The results of the first experiment demonstrated that although the global level was identified faster than the local level in both the central and the peripheral locations of the visual field (global advantage), the pattern of global interference varied across the visual field. Consistency of global and local levels increased the speed of processing of the local level displayed at the center of the visual field but slowed down the processing of that level at peripheral locations. The results of Experiment 2 demonstrated that it was most likely that the variation in the pattern of global interference was determined by the variable of eccentricity, rather than by the sizes of the global and local levels.     

The forest revisited: More on global precedence

Summary Several issues pertaining to the notion of global precedence, its testing, and its ecological validity are discussed. Global precedence is presented as a claim that, other things being equal, global structure is available in the percept earlier than local features are. It does not state that local processing starts only after global processing is terminated. Since global precedence is a hypothesis about temporal development of percepts, a natural way to test it is to limit exposure duration. Global precedence predicts that local features will be more sensitive to stimulus duration than global ones.An experiment is reported in which subjects were presented with 150 ms exposures of large letters made up of small ones, and had to discriminate either just the large letters or just the small ones. In addition, they had to respond to the presence of a concurrent tone. Local letters were responded to more slowly than global ones, and were associated with more tone errors. The variation of the global level as well as the consistency between the identities of the levels affected the latency to the local letter, but not vice versa. A single small-letter control-condition was used to rule out an explanation in terms of relative size. The effects, albeit weaker than some previous results, are compatible with the hypothesis tested.The results of this experiment are interpreted in the context of an extensive discussion of findings in the paradigm and the generality of the phenomenon assumed to underly them. Possible mechanisms which may mediate global precedence are evaluated. Among them are relative size, lateral masking, diffuse attention, and spatial uncertainty. The magnitude, or even the presence, of global precedence depends on some factors, most prominent of which are visual angle and retinal position. Ecological considerations suggest that proximal sizes and eccentricities which favor global features may be very frequent. Some further subtleties of, as well as problems with, the logic of compound letters are discussed.     

Revenge of the Philosophical Mole: Another Response to David Miller on Nationality

ABSTRACT David Miller has written extensively on the ethical value of the nation. A satisfactory response to Miller's ideas on nationalism requires an assessment of the whole range of his writings on the subject. After stating the outlines of Miller's conception of 'nationality', I evaluate the most important arguments for and against any attribution of ethical importance to the nation. Finally, I assess Miller's commitment to conational ethical priority in the context of duties of justributive justice. My main conclusions are as follows. (i) Miller's conservative strategy of justification is unacceptable, and a critical strategy suggests several plausible arguments for valuing national attachments. These arguments are not conclusive, however, (ii) In so far as Miller's position depends on real historical connections between persons, it is susceptible to the objection from historical myth. (iii) Miller offers an unexpected and ultimately unsuccessful response to the claim that national sentiments are partial and hence biased, (iv) Miller provides no good reason to believe that the duties of distributive justice are owed in the first instance to conationals.     

复合字母刺激心理旋转加工中的整体优先效应

采用复合字母材料结合正镜像判断任务,首次揭示了心理旋转加工中的整体优先效应。实验一延长复合字母材料的呈现时间,检验心理旋转实验常用的正/镜像判断任务中的视知觉整体优先效应;实验二将实验一的复合字母材料旋转一定角度,考察心理旋转加工中的整体优先效应。结果发现：（1）延长复合字母呈现时间后的字母正镜像判断任务中,被试判断大字母和判断小字母的时间没有显著差异,并且大小字母是否一致对大字母判断和小字母判断的影响无显著差异;（2）在排除了视知觉的整体优先效应存在的情况下,发现心理旋转加工中存在明显的整体优先效应,大字母（整体）旋转条件下的反应时显著短于小字母（局部）旋转条件下的反应时;（3）旋转角度一致性对大字母旋转和小字母旋转条件下的反应时均无显著影响,表明心理旋转的整体优先效应模式可能有别于视知觉加工的整体优先效应模式     

Effects of good form and spatial frequency on global precedence

Does the global precedence effect depend on the goodness of the global form and low spatial frequencies? In Experiments 1 and 2, under a variety of attentional and task conditions, a global advantage in response time (RT) occurred in “good,” many-element compound patterns but not in “poor,” few-element patterns (unless the local elements were too small to be easily recognized). Symmetric interference effects were found in all patterns, however, suggesting that global and local information were encoded in parallel and that the global advantage in RT involved some postperceptual processes. Experiments 3A and 3B showed that the global advantage in RT and perceived pattern goodness depend on low spatial frequencies: Lowpass-filtered patterns rated as “good” showed the usual global advantage in RT, but highpass-filtered, many-element forms rated as “poor” did not. These findings suggest that a global advantage in RT requires an unambiguous global form conveyed by low spatial frequencies.     

Global precedence as a postperceptual effect: An analysis of speed-accuracy tradeoff functions

Two experiments examined the speed-accuracy tradeoff for stimuli used by Martin (1979), some of which have a Stroop-like conflict between the relevant (to-be-judged) and the irrelevant aspect. Speed of transmitting information about a local aspect was significantly reduced when the irrelevant global aspect conflicted with the relevant local aspect, while speed of transmitting information about the global aspect was not affected when the irrelevant local aspect conflicted with the relevant global aspect. This result, when extrapolated to the accuracy level of an ordinary reaction-time task, fitted very well the reaction-time predictions of the global precedence model proposed by Navon (1977). However, other results were incongruent with the fundamental assumption of that model: that global features are accumulated with temporal priority over local features. The finding that, independently of speed, information transmission of the global aspect started later when the irrelevant local aspect was conflicting, corroborates Miller’s (1981a) conclusion that global and local features are available with a similar time course. Global precedence is therefore a postperceptual effect; absence of interaction with S-R compatibility suggested that it operated before the response selection stage. The term global dominance may be preferred, because it avoids the implication of prior availability for the global aspect. Furthermore, the possibility of whether Stroop conflict should be considered a necessary condition for global dominance is discussed.     

儿童整体-局部加工中的负启动现象

采用2种元素疏密程度的复合数字刺激和启动范式,7岁和11岁2个年龄组的小学生分别在注意整体水平和注意局部水平的条件下对探测刺激进行选择反应。结果发现元素疏密程度可以影响知觉优先,而知觉优先与整体局部水平间的负启动之间没有一致的发展关系,说明与负启动有关的注意分配机制可能比知觉组织发展的晚。     

The global precedence effect is not affected in inhibition of return

This study assessed whether inhibitory processes occurring in IOR affect perceptual processing of hierarchically organised stimuli. Experiment 1 used a global/local task that presented stimuli to the left or the right side. Results showed a global task advantage and a larger interference in the local than in the global task—the global precedence effect (GPE). These effects were larger than in previous studies using centrally presented stimuli, which suggests a greater involvement of low spatial frequency analysis with peripheral than with central stimuli. Experiment 2 combined the global/local task with IOR. Results replicated those of Experiment 1 but there was no interaction with stimulus location. That is, the GPE was not affected in IOR. Thus, we conclude that the GPE and inhibitory processing occurring in IOR are subserved by different mechanisms.     

The effects of precedence on Navon-induced processing bias in face recognition

Macrae and Lewis (2002) showed that repeated reporting of the global dimension of Navon stimuli improved performance in a subsequent face identification task, whilst reporting the features of the Navon stimuli impaired performance. Using a face composite task, which is assumed to require featural processing, Weston and Perfect (2005) showed the complementary pattern: Featural responding to Navon letters speeded performance. However, both studies used Navon stimuli with global precedence, in which the overall configuration is easier to report than the features. Here we replicate the two studies above, whilst manipulating the precedence (global or featural) of the letter stimuli in the orientation task. Both studies replicated the previously reported findings with global precedence stimuli, but showed the reverse pattern with local precedence stimuli. These data raise important questions as to what is transferred between the Navon orientation task and the face-processing tasks that follow.     

Typical hierarchical processing in autistic adults

ABSTRACT

Previous research suggests that autistic individuals exhibit atypical hierarchical processing, however, most of these studies focused solely on children. Thus, the main aim of the current study was to investigate the presence of atypical local or global processing in autistic adults using a traditional divided attention task with Navon’s hierarchical figures. Reaction time data of 27 autistic and 25 neurotypical (NT) adults was analysed using multilevel modelling and Bayesian analysis. The results revealed that autistic, like NT, adults experienced a global precedence effect. Moreover, both autistic and NT participants experienced global and local interference effects. In contrast to previous findings with children, the current study suggests that autistic adults exhibit a typical, albeit unexpected, processing of hierarchical figures.     

Global-feature classification can be acquired more rapidly than local-feature classification in both humans and pigeons

When humans process visual stimuli, global information often takes precedence over local information. In contrast, some recent studies have pointed to a local precedence effect in both pigeons and nonhuman primates. In the experiment reported here, we compared the speed of acquisition of two different categorizations of the same four geometric figures. One categorization was on the basis of a local feature, the other on the basis of a readily apparent global feature. For both humans and pigeons, the global-feature categorization was acquired more rapidly. This result reinforces the conclusion that local information does not always take precedence over global information in nonhuman animals.     

Positive Affect and Flexibility: Overcoming the Precedence of Global over Local Processing of Visual Information

Previous findings on the relationship between positive mood and global processing are often based on visual matching tasks that involve a choice between global and local strategies. Preferences for global processing in positive mood, however, do not imply a reduced ability to process locally. The present experiment tested the assumption that positive affect increases flexibility in cognitive processing as indicated by the ability to overcome global precedence, and to respond rapidly to non-dominant (local) features when the task necessitates it. Consistent with expectations, participants responded significantly faster to local targets after positive compared to neutral and negative prime words. The typical precedence of global over local processing observed after neutral and negative prime words was reversed after positive prime words. Findings support the assumption that positive affect increases cognitive flexibility. Furthermore, findings suggest that mood-related preferences in global versus local processing cannot be generalized to processing ability.