Effects Of Spatial Distance Research Articles

Attention Alters Visual Plasticity during Exposure-Based Learning

It is generally believed that attention enhances the processing of sensory information during perception and learning. Here we report that, contrary to common belief, attention limits the degree of plasticity induced by repeated exposure to image features. Specifically, daily exposure to oriented stimuli that are not linked to a specific task causes an orientation-specific improvement in perceptual performance along the "exposed" axes. This effect is modulated by attention: human subjects showed a larger improvement in orientation discrimination when attention is directed toward the location where stimuli are presented. However, the capacity to perform discriminations away from the exposed orientation is enhanced when the exposure stimuli are unattended. Importantly, the improvement in orientation discrimination at the unattended location leads to a robust enhancement in the discrimination of complex stimuli, such as natural texture images, with orientation components along the exposed axes, whereas the improvement in orientation discrimination at the attended location exhibits only weak transfer to complex stimuli. These results indicate that sensory adaptation by passive stimulus exposure should be viewed as a form of perceptual learning that is complementary to practice-based learning in that it reduces constraints on generalization.

Genetic and community similarities are correlated in endemic‐rich springs of the northern Chihuahuan Desert

ABSTRACTAim Species diversity and genetic diversity within a taxon are intrinsic parts of global biodiversity. These two levels of biodiversity can show strong correlation due to a variety of reasons (i.e. parallel processes affecting both communities and populations, genotypes of a numerically or functionally dominant species affecting community composition, a species assemblage selecting for a particular genotype by affecting its selection regime). We examined correlations between species and genetic biodiversity in four isolated endemic‐rich spring systems in a hot desert and their potential link to environmental variables and physical isolation.Location Chihuahuan Desert spring systems in the Pecos River basin of New Mexico and Texas, USA.Methods We compared species richness of fish and benthic macroinvertebrate communities to within‐population allelic richness of amphipods (monophyletic Gammarus spp.) and Pecos gambusia (Gambusia nobilis) using Mantel tests. We also compared pairwise community similarities with pairwise genetic identities of populations among the same groups. We tested correlations among diversity, similarity and environmental variables after controlling for the effects of spatial distances using partial Mantel tests. We partitioned genetic and species diversity into three spatial scales (i.e. individual springs, individual spring systems, the entire region) using AMOVA and partition.Results We found strong correlations between invertebrate species richness and mosquitofish allelic richness. We found even stronger correlations of amphipod and gambusia genetic identities with fish and invertebrate community similarities; these were best explained by geographic distance rather than abiotic environmental factors. Most of the taxa and communities exhibited the largest proportion of diversity at the regional level.Main conclusions Our results suggest that drift and migration are the mechanisms that best explain our observations, and although α‐diversity among genes and species may not be strongly correlated, the pattern of species and allelic complementarity among these groups seems to be concordant at the regional level.

Spatial scale of GIS‐derived categorical variables affects their ability to separate sites by community composition

Abstract.Questions: How well do GIS‐derived categorical variables (e.g., vegetation, soils, geology, elevation, geography, and physiography) separate plots based on community composition? How does the ability to distinguish plots by community composition vary with spatial scale, specifically number of patch types, patch size and spatial correlation? Both these questions bear on the effective use of stratifying variables in landscape ecology.Location: Arctic tundra; Bering Land Bridge National Preserve, northwestern Alaska, USA.Methods: We evaluated the strength of numerous alternative stratifying variables using the multi‐response permutation procedure (MRPP). We also created groups based on lichen community composition, using cluster analyses, and evaluated the relationship between these groups and groupings within categorical variables using Mantel tests. Each test represents different measures of community separation, which were then evaluated with respect to each variable's spatial characteristics.Results: We found each categorical variable derived from GIS separated lichen communities to some degree. Separation success ranged from strong (Alaska Subsections) to weak (Watersheds and Reindeer Ownership). Lichen community groups derived from cluster analysis demonstrated statistically significant relationships with 13 of the 17 categorical variables. Partialling out effects of spatial distance had little effect on these relationships.Conclusions: Greater number of patch types and larger average patch sizes contribute to optimal success in separating lichen communities; geographic distance did not appear to significantly alter separation success. Group distinctiveness or strength increased with more patch types or groups. Alternatively, congruence between lichen community types derived from cluster analysis and the 17 categorical variables was inversely related to patch size and spatial correlation.

Effect of spatial distance to the task stimulus on task-irrelevant perceptual learning of static Gabors

It was previously shown that sensitivity improvements to a task-irrelevant motion direction can be obtained when it is presented in concurrence with observers' performance of an attended task (A. R. Seitz & T. Watanabe, 2003; T. Watanabe, J. E. Náñez, & Y. Sasaki, 2001). To test whether this task-irrelevant perceptual learning (TIPL) is specific for motion and to clarify the relationships between the observer's task and the resultant TIPL, we investigated the spatial profile of the sensitivity enhancement for a static task-irrelevant feature. During the training period, participants performed an attentionally demanding character identification task at one location, whereas subthreshold, static, Gabor patches, which were masked in noise, were presented at different locations in the visual field. Subjects' sensitivity to the Gabors was compared between the pre- and posttraining tests. First, we found that TIPL extends to learning of static visual stimuli. Thus, TIPL is not a specialized process to motion stimuli. As to the effect of spatial location, the largest improvement was found for the Gabors presented in closest proximity to the task. These data indicate that the learning of the task-irrelevant visual feature significantly depends on the task location, with a gradual attenuation according to the spatial distance between them. These findings give further insights into the mechanism of perceptual learning.

Long-range regressions to previously read words are guided by spatial and verbal memory

To examine the nature of the information that guides eye movements to previously read text during reading (regressions), we used a relatively novel technique to request a regression to a particular target word when the eyes reached a predefined location during sentence reading. A regression was to be directed to a close or a distant target when either the first or the second line of a complex two-line sentence was read. In addition, conditions were created that pitted effects of spatial and linguistic distance against each other. Initial regressions were more accurate when the target was spatially near, and effects of spatial distance dominated effects of verbal distance. Initial regressions rarely moved the eyes onto the target, however, and subsequent "corrective" regressions that homed in on the target were subject to general linguistic processing demands, being more accurate during first-line reading than during second-line reading. The results suggest that spatial and verbal memory guide regressions in reading. Initial regressions are primarily guided by fixation-centered spatial memory, and corrective regressions are primarily guided by linguistic knowledge.

Effect of spatial distance on perceptual motion grouping

Biological motion perception is the perceptual phenomenon that induces human moving form as the sum of coherent local motions. A part such as an arm is organized by the motion grouping of coherently moving dots. To clarify the spatial mechanism of the local motion integration process for motion grouping, we studied the influence of distance between coherently moving dots and the amount of background noise on the perceptual strength of motion grouping. The perception of motion grouping was strong when the coherently moving dots were close to each other, and was attenuated by increasing the distance between the coherently moving dots. The perception of motion grouping was also strong when the number of noise dots was small, and weak when it was large. We used various combinations of the distance between coherent moving dots and the number of the noise dots, and when the ratio of the distance between coherently moving dots to the average distance of the noise dots was the same, the performance was almost the same. Our results show that the perceptual strength of motion grouping has scale invariant properties with respect to the relationship between the distance between the coherently moving dots and that of the noise dots.

Transcending the "Here": The Effect of Spatial Distance on Social Judgment.

Construal level theory proposes that increasing the reported spatial distance of events produces judgments that reflect abstract, schematic representations of the events. Across 4 experiments, the authors examined the impact of spatial distance on construal-dependent social judgments. Participants structured behavior into fewer, broader units (Study 1) and increasingly attributed behavior to enduring dispositions rather than situational constraints (Study 2) when the behavior was spatially distant rather than near. Participants reported that typical events were more likely and atypical events less likely when events were more spatially distant (Study 3). They were also less likely to extrapolate from specific cases that deviated from general trends when making predictions about more spatially distant events (Study 4). Implications for social judgment are discussed.

Digital opportunity: the digital gap between openness and closeness of relational divide upon the mobile phone usage

The possibility of communication nowadays depends fully on the usage of modern technology. Several digital divides exist with respect to Mobile Phone (MP) usage, and they further aggravate the interpersonal relationship. In personal connection, the availability of MP users can be measured by several indicators, such as phone number sharing behaviour and phone answering strategies. The MP users also look over the necessity of using their MP to communicate with others in daily life. The 'dual availability' model distinguishes active/passive attitude and behaviour of individual's calling and receiving styles. In the relational connection, the usage of MP, which shows multiple dimensions, such as phone contacts, face-to-face contacts and spatial distance effects, implies the openness and closeness of interpersonal relationships. In our research, MP use is a proxy of human behaviour as well as relationships, and it represents a digital opportunity for users to improve their relationship. With regard to the personal connections, caller effects show overwhelming domination over either the media use or relationship change, while the receiver effects show weaker influence. Unilateral relationships and network relationships are respectively influenced by personal and relational connections and consequently demonstrate different appearances.

The spatial distribution of object-based attention

We investigated a core issue in object-based selection: the spatial distribution of attention within and across objects. The method built upon the Egly et al. paradigm. We first replicated the same-object advantage in that paradigm. To examine the spatial distribution of attention within and across objects, we added a manipulation of within-object distance between cue and target. Evidence of spatial distance effects within objects would suggest that object-based selection is inherently spatial, consistent with grouped-array theories (Vecera, 1994) in which object perceptual structure is proposed to constrain the spatial distribution of attention.

Anaphor resolution as a function of spatial distance and priming: exploring the spatial distance effect in situation models.

Anaphor resolution has been found to depend on the spatial distance between the reader's focus of attention and the location of the anaphor referent in a spatially organized situation model (spatial distance effect; Rinck & Bower, 1995). This effect implies that a) the situation model is spatially organized and b) spatial distance has a stronger effect on the resolution of anaphoric reference than the text priming the anaphor referent. In three experiments, adult participants read 12 short narratives about protagonists moving around a building. Mentionning the location of the anaphor referent in text prior to the anaphoric sentence facilitated anaphor resolution. Decreased spatial distance consistently facilitated anaphor resolution, even when priming the anaphor referent affected anaphor resolution more strongly than spatial distance. Results are discussed with regard to the interpretation and reliability of the spatial distance effect and the interaction of different representational levels in the context of multi-level theories of text comprehension.

Direct Distance, Route Distance, and Implied Temporal Distance:Effects on the Accessibility of Situation Model Components

Three experiments investigated whether the spatial distance effect in situation models (Rinck & Bower, 1995) is based on direct distance or on route distance. In all experiments, participants learned the layout of a building before they read narratives about a protagonist's motions and actions in this building. Reading times for target sentences referring to objects located in different rooms of the building were measured. Varying (a) the direct distance between the target object and the protagonist's current location (location room) and (b) the length of the route the protagonist walked from the target object to the location room yielded a direct distance effect (increased reading times with increased direct distance). Qualitatively, this effect was robust against manipulation of the layout learning procedure and the experimental narratives, although it decreased in magnitude. Assuming that variation of route length implies variation of the temporal distance between the protagonist leaving the target object and arriving in the location room, readers were then instructed to monitor the narrative time course. Under this instruction, a route distance effect was observed (increased reading times with increased route length). Results are discussed with regard to the organization of situation models.

Are black workers missing the connection? The effect of spatial distance and employee referrals on interfirm racial segregation.

I use data on the hiring practices and spatial location of firms in four cities to model the process of interfirm racial segregation. When I control for the spatial location of the firm, the use of employee referrals reduced the probability of hiring a black worker by 75% in firms that are less than 10% black. Among all firms, the results suggest that employee referrals are just as important as the geographic location of the firm in generating employment segregation: both increase the predicted level of interfirm racial segregation among blue-collar workers in the cities studied by about 10%.

Are Black Workers Missing the Connection? The Effect of Spatial Distance and Employee Referrals on Interfirm Racial Segregation

I use data on the hiring practices and spatial location of firms in four cities to model the process of interfirm racial segregation. When I control for the spatial location of the firm, the use of employee referrals reduced the probability of hiring a black worker by 75% in firms that are less than 10% black. Among all firms, the results suggest that employee referrals are just as important as the geographic location of the firm in generating employment segregation: both increase the predicted level of interfirm racial segregation among blue-collar workers in the cities studied by about 10%.

Intranest relatedness and nestmate recognition in the meadow ant Formica pratensis (R.)

The impact of intranest relatedness on nestmate recognition was tested in a population of polydomous and monodomous nests of the mound-building ant Formica pratensis. Nestmate recognition was evaluated by testing aggression levels between 37 pairs of nests (n=206 tests). Workers from donor colonies were placed on the mounds of recipient nests to score aggressive interactions among workers. A total of 555 workers from 27 nests were genotyped using four DNA microsatellites. The genetic and spatial distances of nests were positively correlated, indicating budding and/or fissioning as spread mechanisms. Monodomous and polydomous nests did not show different aggression levels. Aggression behavior between nests was positively correlated with both spatial distance and intranest relatedness of recipient colonies, but not with genetic distance or intranest relatedness of donor colonies. Multiple regression analysis revealed a stronger effect of spatial distance than of genetics on aggression behavior in this study, indicating that the relative importance of environment and genetics can be variable in F. pratensis. Nevertheless, the positive regression between intranest relatedness of recipient colonies and aggression in the multiple analysis supports earlier results that nestmate recognition is genetically influenced in F. pratensis and further indicates that foreign label rejection most likely explains our data.

Attending to the parts of a single object: part-based selection limitations.

Studies of object-based attention have demonstrated poorer performance in dividing attention between two objects in a scene than in focusing attention on a single object. However, objects often are composed of several parts, and parts are central to theories of object recognition. Are parts also important for visual attention? That is, can attention be limited in the number of parts processed simultaneously? We addressed this question in four experiments. In Experiments 1 and 2, participants reported two attributes that appeared on the same part or on different parts of a single multipart object. Participants were more accurate in reporting the attributes on the same part than attributes on different parts. This part-based effect was not influenced by the spatial distance between the parts, ruling out a simple spatial attention interpretation of our results. A control study demonstrated that our spatial manipulation was sufficient to observe shifts of spatial attention. This study revealed an effect of spatial distance, indicating that our spatial manipulation was adequate for observing spatial attention. The absence of a distance effect in Experiments 1 and 2 suggests that part-based attention may not rely entirely on simple shifts of spatial attention. Finally, in Experiment 4 we found evidence for part-based attention, using stimuli controlled for the distance between the parts of an object. The results of these experiments indicate that visual attention can selectively process the parts of an object. We discuss the relationship between parts and objects and the locus of part-based attentional selection.

Temporal and spatial distance in situation models.

In two experiments, we investigated how readers use information about temporal and spatial distance to focus attention on the more important parts of the situation model that they create during narrative comprehension. Effects of spatial distance were measured by testing the accessibility in memory of objects and rooms located at differing distances from the protagonist's current location. Before the test probe, an intervening episode was inserted in the narrative. Story time distance was manipulated by stating that the intervening episode lasted for either minutes or hours. Discourse time--that is, time spent reading from prime to test--was manipulated by describing the intervening episode either briefly or at length. Clear effects of story time distance and spatial distance on accessibility were found, whereas discourse time distance did not affect accessibility. The results are interpreted as supporting constructionist theories of text comprehension.

The metrics of spatial situation models.

The authors investigated the metrics of spatial distance represented in situation models of narratives. In 3 experiments, a spatial gradient of accessibility in situation models was observed: The accessibility of objects contained in the situation model decreased with increasing spatial distance between the object and the reader's focus of attention. The first 2 experiments demonstrated that this effect of spatial distance was purely categorical rather than Euclidean: Accessibility depended on the number of rooms located between the object and the focus of attention, not on the size of the rooms. Experiment 3 revealed, however, that participants were able to use information about Euclidean distance in a secondary task when necessary. The implications of these results for theories of narrative comprehension and hierarchical versus nonhierarchical theories of spatial memory are discussed.

Illusional effects of spatial distance between focal and contextual parts of a modified Müller-Lyer figure.

Visual integration of spatially separated stimuli was studied in a modified Müller-Lyer illusional pattern by varying the distance between the shaft and the contextual lines. Using the method of constant stimuli, the data from 265 participants indicated a significant inverted-U trend which is contrary to previously reported findings.

Effect of spatial distance on backward and foreward lateral masking

Dans une expérience de masquage latéral, on étudie les modifications de l'intensité apparente d'un stimulus lumineux lorsqu'il est suivi ou précédé d'un stimulus masquant voisin. Les facteurs expérimentaux sont: (i) le délai Δ t entre les deux stimulus (axe des abscisses sur les graphes) et (ii) l'écart spatial entre les stimulus. Les variations de la brillance (estimée sur une échelle d'intervalle en 9 points) sont analysées par rapport à la valeur de référence (V.R.: estimation du stimulus-test présenté seul). On obtient un effet de diminution de brillance lorsque les deux stimulus (test et masquant) sont proches à la fois dans le temps et dans l'espace (délai inférieur à 50 ms et écart inférieur à 10 minutes d'angle). Si l'écart spatial est augmenté (entre 0 et 10′), cet effet de masquage est atténué; cette atténuation est importante surtout en situation rétroactive contrairement à l'atténuation obtenue par d'autres facteurs (diminution d'énergie du stimulus masquant ou bien séparation dichoptique). On obtient un effet d'augmentation de brillance lorsqu'un intervalle, temporel ou spatial, est augmenté: le maximum étant obtenu lorsque le stimulus-test suit le stimulus inducteur (situation proactive), pour les délais de 75–150 ms. Ces résultats sont discutés en fonction des données obtenues dans d'autres travaux analysant les effets d'inhibition et de facilitation dans des expériences d'interaction spatiale ou temporelle.