Individual differences in spatial relation processing: effects of strategy, ability, and gender

Numerous studies have focused on the distinction between categorical and coordinate spatial relations. Categorical relations are propositional and abstract, and often related to a left hemisphere advantage. Coordinate relations specify the metric information of the relative locations of objects, and can be linked to right hemisphere processing. Yet, not all studies have reported such a clear double dissociation; in particular the categorical left hemisphere advantage is not always reported. In the current study we investigated whether verbal and spatial strategies, verbal and spatial cognitive abilities, and gender could account for the discrepancies observed in hemispheric lateralization of spatial relations. Seventy-five participants performed two visual half field, match-to-sample tasks (Van der Ham, van Wezel, Oleksiak, & Postma, 2007; Van der Ham, Raemaekers, van Wezel, Oleksiak, and Postma, 2009) to study the lateralization of categorical and coordinate relation processing. For each participant we determined the strategy they used in each of the two tasks. Consistent with previous findings, we found an overall categorical left hemisphere advantage and coordinate right hemisphere advantage. The lateralization pattern was affected selectively by the degree to which participants used a spatial strategy and by none of the other variables (i.e., verbal strategy, cognitive abilities, and gender). Critically, the categorical left hemisphere advantage was observed only for participants that relied strongly on a spatial strategy. This result is another piece of evidence that categorical spatial relation processing relies on spatial and not verbal processes.     

What types of visual recognition tasks are mediated by the neural subsystem that subserves face recognition?

Three divided visual field experiments tested current hypotheses about the types of visual shape representation tasks that recruit the cognitive and neural mechanisms underlying face recognition. Experiment 1 found a right hemisphere advantage for subordinate but not basic-level face recognition. Experiment 2 found a right hemisphere advantage for basic but not superordinate-level animal recognition. Experiment 3 found that inverting animals eliminates the right hemisphere advantage for basic-level animal recognition. This pattern of results suggests that the cognitive and neural mechanisms underlying face recognition are recruited when computational demands of a shape representation task are best served through the use of coordinate (rather than categorical) spatial relations.     

Hemispheric specialization for categorical and coordinate spatial representations: A reappraisal

The purpose of the present study was to examine Kosslyn's (1987) claim that the left hemisphere (LH) is specialized for the computation of categorical spatial representations and that the right hemisphere (RH) is specialized for the computation of coordinate spatial representations. Categorical representations involve making judgements about the relative position of the components of a visual stimulus (e.g., whether one component is above/below another). Coordinate representations involve calibrating absolute distances between the components of a visual stimulus (e.g., whether one component is within 5 mm of another). Thirty-two male and 32 female undergraduates were administered two versions of a categorical or a coordinate task over three blocks of 36 trials. Within each block, items were presented to the right visual field-left hemisphere (RVF-LH), the left visual field-right hemisphere (LVF-RH), or a centralized position. Overall, results were more supportive of Kosslyn's assertions concerning the role played by the RH in the computation of spatial representations. Specifically, subjects displayed an LVF-RH advantage when performing both versions of the coordinate task. The LVF-RH advantage on the coordinate task, however, was confirmed to the first block of trials. Finally, it was found that males were more likely than females to display faster reaction times (RTs) on coordinate tasks, slower RTs on categorical tasks, and an LVF-RH advantage in computing coordinate tasks.     

类别空间关系加工系统和数量空间关系加工系统的分离 ——来自多领域的研究证据

Kosslyn认为人类的空间关系加工系统分为类别空间关系加工子系统和数量空间关系加工子系统,这两个子系统不仅存在功能上的分离,并且存在大脑神经水平的分离,这种神经水平的分离表现为两种空间关系加工的大脑半球偏向,即类别空间关系加工的左半球偏向与数量空间关系加工的右半球偏向。对两种空间关系加工的研究,涉及的领域从低水平的空间知觉,至表象、记忆、语言、行动及物体识别等,涉及的研究方法包括半视野速示法,神经网络模拟,PET, fMRI, ERP, rTMS,脑损伤病人的研究及比较动物研究。综合现有研究,虽然大多数研究中得到的脑半球偏向为两种加工子系统在神经水平的分离提供了证据,但不同研究中脑半球偏向的获得是相当不稳定的,并且受到研究方法因素的影响。尽管造成神经水平的分离似乎与大脑左右半球对具有不同感受野特征的神经元输出的偏向有一定的关系,但这仍需要进一步的研究证据     

Lateralized effects of categorical and coordinate spatial processing of component parts on the recognition of 3D non-nameable objects

Participants performed two object-matching tasks for novel, non-nameable objects consisting of geons. For each original stimulus, two transformations were applied to create comparison stimuli. In the categorical transformation, a geon connected to geon A was moved to geon B. In the coordinate transformation, a geon connected to geon A was moved to a different position on geon A. The Categorical task consisted of the original and the categorically transformed objects. The Coordinate task consisted of the original and the coordinately transformed objects. The original object was presented to the central visual field, followed by a comparison object presented to the right or left visual half-fields (RVF and LVF). The results showed an RVF advantage for the Categorical task and an LVF advantage for the Coordinate task. The possibility that categorical and coordinate spatial processing subsystems would be basic computational elements for between- and within-category object recognition was discussed.     

视觉空间关系判断的分离与协同

采用任务表征相互影响范式,通过三个实验探讨了类别空间关系判断和数量空间关系判断的加工特性和相互关系.结果表明:(1)先行类别关系启动有利于数量空间关系判断,对类别空间关系判断没有影响;先行数量关系启动对两个判断任务均无影响.(2)先行类别关系干扰降低两个空间关系判断的绩效,先行数量关系干扰对两个空间关系判断没有影响.(3)先行类别关系对空间关系判断的启动和干扰效应不局限于特定条件,具有普遍性.研究提示,右脑为优势半球的数量关系加工以左脑为优势半球的类别关系加工为基础,支持视觉空间认知加工既分离又协同的观点.     

A left cerebral hemisphere’s superiority in processing spatial-categorical information in a non-verbal semantic format

It has been shown that the left and right cerebral hemispheres (LH and RH) respectively process qualitative or “categorical” spatial relations and metric or “coordinate” spatial relations. However, categorical spatial information could be thought as divided into two types: semantically-coded and visuospatially-coded categorical information. We examined whether a LH’s advantage in processing semantic-categorical information is observed in a non-verbal format, and also whether semantic- and visuospatial-categorical processing are differentially lateralized. We manipulated the colors and positions of the standard traffic light sign as semantic- and visuospatial-categorical information respectively, and tested performance with the divided visual field method. In the semantic-categorical matching task, in which the participants judged if the semantic-categorical information of a successive cue and target was the same, a right visual field advantage was observed, suggesting a LH’s preference for processing semantic-categorical information in a non-verbal format. In the visuospatial-categorical matching task, in which the participants judged if the visuospatial-categorical information of a successive cue and target was identical, a left visual field advantage was obtained. These results suggest that the processing of semantic-categorical information is lateralized in LH, and we discuss the dissociation between the two types of categorical information.     

The role of stimulus factors in making categorical and coordinate spatial judgments

We report three experiments which investigate the lateralization of categorical and coordinate processing. In all experiments, participants judged the position of a dot relative to a line. We manipulated display luminance (controlling for contrast), polarity (black-on-white versus white-on-black displays), and exposure duration (100, 150, and 200 ms). The results showed a left visual field-right hemisphere advantage for coordinate judgments, but only under highly prescribed conditions. We argue that stimulus and procedural factors are critical in determining the hemisphere by task interaction.     

Lateralization of spatial categories: A comparison of verbal and visuospatial categorical relations

Many reports show that spatial relations between and within objects show differences in hemispheric lateralization. Coordinate, metric relations concerning distances are processed with a right-hemisphere advantage, whereas a left-hemisphere advantage is thought to be related to categorical, abstract relations (Kosslyn, 1987). Kemmerer and Tranel (2000) argued that the left-hemisphere advantage for categorical processing might apply only for verbal spatial categories, however, whereas a right-hemisphere advantage is related to visuospatial categories. To test this idea, we examined categorical processing for stimuli in both verbal and visuospatial formats, with a visual half-field, match-to-sample design. In Experiment 1, we manipulated the format of the second stimulus to compare response patterns for both verbal and visuospatial stimuli. In Experiment 2, we varied the expectancy of the format of the second stimulus, allowing for an assessment of strategy use. The results showed that a left-hemisphere advantage was related to verbal stimulus format only, but not in all conditions. A right-hemisphere advantage was found only with a visuospatial expectancy, visuospatial format, and brief interval. The theory we present to explain these results proposes that the lateralization related to basic categorical processing can be strongly influenced by verbal characteristics and, to some extent, by additional coordinate processing. The lateralization measured in such cases does not represent lateralization related purely to categorical processing, but to these additional effects as well. This stresses the importance of careful task and stimulus design when examining categorical processing in order to reduce the influence of those additional processes.     

Effects of the global and local attention on the processing of categorical and coordinate spatial relations

Participants made categorical or coordinate spatial judgments on the global or local elements of shapes. Stimuli were composed of a horizontal line and two dots. In the Categorical task, participants judged whether the line was above or below the dots. In the Coordinate task, they judged whether the line would fit between the dots. Stimuli were made hierarchical so that the global patterns composed of a “global line” made of local dots-and-line units, and “global dot” made of a single dots-and-line unit. The results indicated that the categorical task was better performed when participants attended to the local level of the hierarchical stimuli. On the other hand, the coordinate task was better performed when they attended to the global level. These findings are consistent with computer simulation models of the attentional modulation of neuronal receptive fields’ size suggesting that (1) coordinate spatial relations are more efficiently encoded when one attends to a relatively large region of space, whereas (2) categorical spatial relations are more efficiently encoded when one attends to a relatively small region of space.     

Judgments of relative position and distance on representations of spatial relations

This article examines Kosslyn's (1987) hypothesis of the unequal capacity of cerebral hemispheres to process categorical and coordinate spatial relations. Experiment 1 comprised 4 different tasks and failed to support this hypothesis in normal Ss. With the same stimulus patterns as in Kosslyn's study, the results failed to confirm cerebral asymmetry for representing the 2 types of spatial relations, in normal (Experiment 2) and commissurotomized (Experiment 3) Ss. In Experiment 4, a reduction in stimulus luminance produced a partial confirmation of the hypothesis as the right hemisphere proved more adept than the left hemisphere at operating on coordinate representations, whereas both were equally competent at processing categorical spatial-relation representations. The results suggest that the 2 hemispheres can operate on both types of spatial relations, but their respective efficiency depends on the quality of the representations to be processed.     

Upper and lower visual field differences in categorical and coordinate judgments

Kosslyn (1987) theorized that the left and right hemispheres differ in processing categorical and coordinate spatial relationships, respectively. Previc (1990) hypothesized that the upper and lower visual fields are functionally specialized for visual search and visuomotor manipulations, respectively. Conceptual similarities between these two theories suggested possible upper visual field advantages for categorical judgments and lower visual field advantages for coordinate judgments. In the present two experiments, subjects made either categorical or coordinate judgments to stimuli in the upper left, upper right, lower left, or lower right visual fields. The first experiment manipulated categorical/coordinate judgments as a between-subjects variable. The second experiment manipulated categorical/coordinate judgments as a within-subjects variable. In the first experiment, reaction times (RTs) for categorical judgments were equal in all visual fields except the lower left, in which RTs were slower. For coordinate judgments, RTs were equal in all visual fields except the lower left, in which RTs were faster. In general, these effects were replicated in the second experiment. However, there appeared to be consequences associated with manipulating the categorical/coordinate variable in a within-subjects fashion. The requirements of visual search versus visuomotor processes appear to map onto the nature of categorical versus coordinate processing, respectively, suggesting possible upper-lower visual field differences in categorical versus coordinate processing.     

Egocentric metric representations in peripersonal space: A bridge between motor resources and spatial memory

Research on visuospatial memory has shown that egocentric (subject-to-object) and allocentric (object-to-object) reference frames are connected to categorical (non-metric) and coordinate (metric) spatial relations, and that motor resources are recruited especially when processing spatial information in peripersonal (within arm reaching) than extrapersonal (outside arm reaching) space. In order to perform our daily-life activities, these spatial components cooperate along a continuum from recognition-related (e.g., recognizing stimuli) to action-related (e.g., reaching stimuli) purposes. Therefore, it is possible that some types of spatial representations rely more on action/motor processes than others. Here, we explored the role of motor resources in the combinations of these visuospatial memory components. A motor interference paradigm was adopted in which participants had their arms bent behind their back or free during a spatial memory task. This task consisted in memorizing triads of objects and then verbally judging what was the object: (1) closest to/farthest from the participant (egocentric coordinate); (2) to the right/left of the participant (egocentric categorical); (3) closest to/farthest from a target object (allocentric coordinate); and (4) on the right/left of a target object (allocentric categorical). The triads appeared in participants' peripersonal (Experiment 1) or extrapersonal (Experiment 2) space. The results of Experiment 1 showed that motor interference selectively damaged egocentric-coordinate judgements but not the other spatial combinations. The results of Experiment 2 showed that the interference effect disappeared when the objects were in the extrapersonal space. A third follow-up study using a within-subject design confirmed the overall pattern of results. Our findings provide evidence that motor resources play an important role in the combination of coordinate spatial relations and egocentric representations in peripersonal space.     

视觉表象产生的大脑半球专门化效应

采用Kosslyn单侧视野速示技术, 以英文字母图片为学习材料, 通过三个实验考察了视觉表象产生的大脑半球专门化效应。实验一提出在两种类型的视觉表象产生任务中, 有两种截然不同的加工起作用, 但却不能直接证实这两种不同加工机制的存在。实验二和实验三则进一步证实了两种表象产生任务具有不同的认知加工机制, 并表现出不同的大脑半球专门化效应。上述研究表明: 大脑两半球均参与产生视觉心理表象, 但分工不同, 并表现出不同的单侧化效应: 大脑左半球通过运用类别空间关系产生表象更有效, 大脑右半球运用数量空间关系产生表象更有效。结果进一步拓展了Kosslyn关于视觉空间关系加工的大脑半球专门化观点。     

The roles of categorical and coordinate spatial relations in recognizing buildings

Categorical spatial information is considered more useful for recognizing objects, and coordinate spatial information for guiding actions??for example, during navigation or grasping. In contrast with this assumption, we hypothesized that buildings, unlike other categories of objects, require both categorical and coordinate spatial information in order to be recognized. This hypothesis arose from evidence that right-brain-damaged patients have deficits in both coordinate judgments and recognition of buildings and from the fact that buildings are very useful for guiding navigation in urban environments. To test this hypothesis, we assessed 210 healthy college students while they performed four different tasks that required categorical and coordinate judgments and the recognition of common objects and buildings. Our results showed that both categorical and coordinate spatial representations are necessary to recognize a building, whereas only categorical representations are necessary to recognize an object. We discuss our data in view of a recent neural framework for visuospatial processing, suggesting that recognizing buildings may specifically activate the parieto-medial-temporal pathway.     

Exogenous attention differentially modulates the processing of categorical and coordinate spatial relations

Carrasco and her colleagues have suggested that exogenous attention reduces the size of receptive fields at an attended location (Gobell & Carrasco, 2005; Yeshurun & Carrasco, 1998, 2000). Based on the hypothesis that categorical and coordinate spatial relations are more efficiently processed by smaller and larger receptive fields, respectively, we predicted that exogenous attention would be more beneficial to the processing of categorical spatial relations than coordinate spatial relations while it would disrupt the processing of coordinate spatial relations. To test these hypotheses, participants were tested using a variant of Posner's (1980) attentional cueing paradigm. Exogenous attention produced larger facilitative effects on categorical spatial processing than on coordinate spatial processing at a short cue-target stimulus onset asynchrony (100 ms, Experiment 1, N = 28), and this result was replicated regardless of cue size in Experiment 2 (N = 24). When the coordinate judgment was sufficiently difficult, exogenous attention disrupted the processing of coordinate spatial relations (Experiment 3, N = 28). These findings indicate that exogenous attention can differentially modulate the processing of categorical and coordinate spatial relations.     

Hemispheric asymmetries in categorical judgments of direction versus coordinate judgments of velocity of motion

Three experiments on visual field differences in motion perception are reported. Experiment 1 employed circular stimuli that grew or shrank either quickly or slowly. Experiments 2 and 3 employed circles that moved upward or downward either quickly or slowly. Judgments based on categorical equivalence classes (i.e., grow/shrink, upward/downward) generally yielded small and nonsignificant right visual field advantages. Judgments based on the precise coordinates of motion (i.e., quickly/slowly) yielded significant left visual field advantages across all three experiments. Results are interpreted in light of Kosslyn’s (1987) model of hemispheric differences in the processing of categorical versus coordinate spatial relations.     

Hemispheric processing of anaphoric inferences: the activation of multiple antecedents

This research investigates the hemispheric processing of anaphors when readers activate multiple antecedents. Participants read texts promoting an anaphoric inference and performed a lexical decision task to inference-related target words that were consistent (Experiment 1) or inconsistent (Experiment 2) with the text. These targets were preceded by constrained or less constraining text and were presented to participants' right visual field-left hemisphere or to their left visual field-right hemisphere. In Experiment 1, both hemispheres showed facilitation for consistent antecedents and the right hemisphere showed an advantage over the left hemisphere in processing antecedents when preceded by less constrained text. In Experiment 2, the left hemisphere only showed negative facilitation for inconsistent antecedents. When readers comprehend text with multiple antecedents: both hemispheres process consistent information, the left hemisphere inhibits inconsistent information, and the right hemisphere processes less constrained information.     

A right visual field advantage for visual processing of manipulable objects

Information about object-associated manipulations is lateralized to left parietal regions, while information about the visual form of tools is represented bilaterally in ventral occipito-temporal cortex. It is unknown how lateralization of motor-relevant information in left-hemisphere dorsal stream regions may affect the visual processing of manipulable objects. We used a lateralized masked priming paradigm to test for a right visual field (RVF) advantage in tool processing. Target stimuli were tools and animals, and briefly presented primes were identical to or scrambled versions of the targets. In Experiment 1, primes were presented either to the left or to the right of the centrally presented target, while in Experiment 2, primes were presented in one of eight locations arranged radially around the target. In both experiments, there was a RVF advantage in priming effects for tool but not for animal targets. Control experiments showed that participants were at chance for matching the identity of the lateralized primes in a picture?Cword matching experiment and also ruled out a general RVF speed-of-processing advantage for tool images. These results indicate that the overrepresentation of tool knowledge in the left hemisphere affects visual object recognition and suggests that interactions between the dorsal and ventral streams occurs during object categorization.     

The nature of categorical and coordinate spatial relation processing: An interference study

Spatial relation information can be encoded in two different ways: categorically, which is abstract, and coordinately, which is metric. Although categorical and coordinate spatial relation processing is commonly conceived as relying on spatial representations and spatial cognitive processes, some suggest that representations and cognitive processes involved in categorical spatial relation processing can be verbal as well as spatial. We assessed the extent to which categorical and coordinate spatial relation processing engages verbal and spatial representations and processes using a dual-task paradigm. Participants performed the classical dot-bar paradigm and simultaneously performed either a spatial tapping task, or an articulatory suppression task. When participants were requested to tap blocks in a given pattern (spatial tapping), their performance decreased in both the categorical and coordinate tasks compared to a control condition without interference. In contrast, articulatory suppression did not affect performance in either spatial relation task. A follow-up experiment indicated that this outcome could not be attributed to different levels of difficulty of the two interference tasks. These results provide strong evidence that both coordinate and categorical spatial relation processing relies mainly on spatial mechanisms. These findings have implications for theories on why categorical and coordinate spatial relations processing are lateralised in the brain.