Representations of interobject spatial relations in long-term memory

A growing body of evidence has indicated that human spatial memory is organized in terms of a small number of reference directions and that interobject spatial relations are represented in terms of these directions (e.g., McNamara, 2003). The goal of the present experiments was to investigate whether the selection of reference directions also affects the fidelity with which interobject spatial relations are represented in memory. In two experiments, participants memorized a layout of nine objects and then performed judgments of relative direction (e.g., “Imagine you are standing at the clock, facing the book. Point to the phone.”) at a remote location. Imagined heading (e.g., at the clock, facing the book) and allocentric target direction (e.g., the direction from clock to phone in the allocentric frame of reference used to define imagined heading) were manipulated independently. The results of both experiments showed that the same directions that were benefited in imagined headings were also benefited in allocentric target directions. These findings indicate that interobject spatial relations are preferentially represented when they coincide with a reference direction.     

Giving Directions: Gender and Perceived Quality

Two related studies examined gender differences in directions given between 2 campus buildings (Experiment 1) and the rated quality of these directions and their authorship in terms of gender (Experiment 2). In the first experiment, 95 participants gave written directions for newcomers to their college campus. No significant gender differences were found in 6 assessment categories adapted from Ward, Newcombe, and Overton (1986). In the second experiment, 14 sets of directions from Experiment 1 were evaluated by 111 participants in a between-subjects design, half evaluating them in terms of the gender of the author and half in terms of the quality of the directions. Results indicated that length (in terms of gender) and errors (in terms of quality) most clearly differentiated the directions. The findings are discussed in terms of the schism between performance and perception.     

On the Affine Structure of Perceptual Space

Affine geometry is a generalization of Euclidean geometry in which distance can be scaled along parallel directions, though relative distances in different directions may be incommensurable. This article presents a new procedure for testing the intrinsic affine structure of a psychological space by having subjects perform bisection judgments over multiple directions. If those judgments are internally consistent with one another, they must satisfy a theorem first proved by Pierre Varignon around 300 years ago. In the experiment reported here, this procedure was employed to measure the perceived structure of a visual ground surface. The results revealed that observers' judgments were systematically distorted relative to the physical environment, but that the judged bisections in different directions had an internally consistent affine structure. Implications of these findings for other possible response tasks are considered.     

Simultaneous specification of amplitudes and directions of bimanual reversal movements

Intermanual interactions are modulated by task requirements in the course of motor preparation. In particular, amplitude coupling is strong when identical amplitudes are specified concurrently for the 2 hands but relaxed when different amplitudes are specified. Similarly, directional coupling is symmetric when symmetric directions are specified concurrently but turns to parallel when parallel directions are specified. Here, the author investigated whether the modulations of amplitude coupling and directional coupling in the course of motor preparation are independent or interact. Application of the timed-response procedure, which enables one to manipulate the time available for motor preparation, in 9 participants revealed a weakly interactive pattern. Directional coupling tended to be reduced when different rather than same amplitudes were specified concurrently, and amplitude coupling tended to be reduced when parallel rather than symmetric directions were specified concurrently. In general, interactive effects were also apparent in the rates at which directions and amplitudes were specified. Those observations are consistent with the notion that intermanual amplitude and direction interference are mediated by different but partially overlapping neural structures.     

Elimination of sex difference in direction giving

Past studies have shown that men provide more cardinal information and mileage estimates than women when describing routes learned from maps. In the current study, we examined whether this sex difference would persist if more legends were added to the maps. The participants looked at maps for 3 min and then wrote down directions from memory. Their usage of cardinal directions, mileage estimates, landmarks, and left–right directions was coded and analyzed. The results showed that men and women used cardinal directions equally for the 4-legend maps, whereas men used more cardinal directions than women for 1-legend maps as shown previously. Our results suggested that subtly drawing attention to cardinal directions successfully eliminated the sex difference in usage, although a different pattern was seen for mileage estimates. The underlying mechanisms are discussed.     

Spatial memory during progressive disorientation

Human spatial representations of object locations in a room-sized environment were probed for evidence that the object locations were encoded relative not just to the observer (egocentrically) but also to each other (allocentrically). Participants learned the locations of 4 objects and then were blindfolded and either (a) underwent a succession of 70 degrees and 200 degrees whole-body rotations or (b) were fully disoriented and then underwent a similar sequence of 70 degrees and 200 degrees rotations. After each rotation, participants pointed to the objects without vision. Analyses of the pointing errors suggest that as participants lost orientation, represented object directions generally "drifted" off of their true directions as an ensemble, not in random, unrelated directions. This is interpreted as evidence that object-to-object (allocentric) relationships play a large part in the human spatial updating system. However, there was also some evidence that represented object directions occasionally drifted off of their true directions independently of one another, suggesting a lack of allocentric influence. Implications regarding the interplay of egocentric and allocentric information are considered.     

The importance of basic concepts in the individual assessment of preschool children

The directions for administering four major preschool instruments were analyzed to determine whether any basic concepts are included in the words spoken by the examiner. Boehm found that young children, especially those from disadvantaged backgrounds, tend to have difficulty with numerous basic concepts. Consequently, the inclusion of several of these concepts in test directions may hinder a preschool child's understanding of what is expected of him (and possibly invalidate his scores). The WPPSI directions were found to include the greatest number of basic concepts, and the ITPA directions included the fewest; the Stanford-Binet and McCarthy Scales were between these extremes. The implications of these findings for individual assessment of young children's abilities were discussed.     

Inconsistency in spatial knowledge

Two experiments examined whether spatial information judged from cognitive maps contains the functional euclidean properties of real maps. In Experiment 1, the six directions between sets of threetriad locations in a town were judged from memory. The angle formed by the two judged directions from a location to the other two locations in a triad was derived. The three derived angles of a triad were then summed. The derived angles were found to be biased toward 90 deg. The sum of the three derived angles of a triad also exceeded 180 deg, which violates the euclidean properties of real maps. In Experiment 2, subjects judged the direction between pairs of American cities in both directions. The judged directions were found to be consistently nonreversible, which is contrary to the properties of euclidean geometry. The study suggests that information judged from cognitive maps can contain internally inconsistent spatial properties, and the results are discussed in terms of current theories of spatial representation.     

Graphics in written directions: Appreciated by readers but not writers

This series of studies investigated the ability of literate adults to exploit communications options that are available to writers but have no counterpart in speech. Specifically it examined people's use of sketches when giving written directions to help a stranger cross town. When writing an informal letter to a friend most directions were given in prose paragraph style (Experiment 1). Almost no-one included a sketch, even if given a street map as an aid. Yet most subjects could draw adequate sketch maps (Experiment 2), and everyone said yes when asked whether they would include a sketch in a letter. So the previous choices were not constrained either by graphic skill or by judgements concerning the appropriateness of a sketch, When people were asked to 'design' the back page of a leaflet they still did not include a sketch (Experiment 3). Experiment 4 showed that any bias in the instructions was towards rather than against the use of sketches. The need to generate the sketch was removed in Experiment 5 where subjects composed the leaflet page from pre-formed sections that included alternative routes in both words and diagrams. Nearly all subjects now included a sketch in their directions. In case subjects previously, in haste, had not considered the possibility of including a sketch map, they were made aware of the drawing option by rating the usability of route information in a variety of communication styles immediately before writing their own directions (Experiment 6). People rated directions that included diagrams as significantly more usable, but still most subjects did not include a sketch in the directions they gave. So the communication styles that readers recognized as successful were not determining their choices as writers. It is suggested that, when giving written directions, inexperienced writers rely too heavily on how they would respond as speakers.     

A comparison of methods for estimating directions in egocentric space

A central issue for researchers of human spatial knowledge, whether focused on perceptually guided action or cognitive-map acquisition, is knowledge of egocentric directions, directions from the body to objects and places. Several methods exist for measuring this knowledge. We compared two particularly important methods, manual pointing with a dial and whole-body rotation (body heading), under various conditions of sensory or memory access to targets. In two experiments, blindfolded body rotation resulted in the greatest variability of performance (variable error), while the manual dial resulted in greater consistent bias (constant error). The variability of performance with body rotation was no greater than that of the dial when subjects' memory loads for directions to targets was reduced by allowing them to peek at targets in between trials, point to concurrent auditory targets, or point with their eyes open. In both experiments, errors with the manual dial were greater for directions to targets that were further from the closest orthogonal axis (ahead, behind, right, left), while errors with body rotation with restricted perceptual access were greater for directions to targets that were further from an axis straight ahead of subjects. This suggests that the two methods will produce evidence of different organizational frameworks for egocentric spatial knowledge. Implications for the structures and processes that underlie egocentric spatial knowledge, and are involved in estimating directions, are discussed, as is the value of decomposing absolute errors into variable and constant errors.     

Auditory spatial concepts in blind football experts

ObjectivesWe compared the spatial concepts given to sounds' directions by blind football players with both blind non-athletes and sighted individuals.MethodParticipants verbally described the directions of sounds around them by using predefined spatial concept labels, under two blocked conditions: 1) facing front, 2) pointing with the hand towards the stimulus.ResultsBlind football players categorized the directions more precisely (i.e., they used simple labels for describing the cardinal directions and combined labels for the intermediate ones) than the other groups, and their categorization was less sensitive to the response conditions than blind non-athletes. Sighted participants' categorization was similar to previous studies, in which the front and back regions were generally more precisely described than the sides, where simple labels were often used for describing directions around the absolute left and right.ConclusionsThe differences in conceptual categorization of sound directions are a) in sighted individuals, influenced by the representation of the visual space b) in blind individuals, influenced by the level of expertise in action and locomotion based on non-visual information, which can be increased by auditive stimulation provided by blind football training.     

Allocentric and egocentric updating of spatial memories

In 4 experiments, the authors investigated spatial updating in a familiar environment. Participants learned locations of objects in a room, walked to the center, and turned to appropriate facing directions before making judgments of relative direction (e.g., "Imagine you are standing at X and facing Y. Point to Z.") or egocentric pointing judgments (e.g., "You are facing Y. Point to Z."). Experiments manipulated the angular difference between the learning heading and the imagined heading and the angular difference between the actual heading and the imagined heading. Pointing performance was best when the imagined heading was parallel to the learning view, even when participants were facing in other directions, and when actual and imagined headings were the same. Room geometry did not affect these results. These findings indicated that spatial reference directions in memory were not updated during locomotion.     

On interference effects in concurrent perception and action

Recent studies have reported repulsion effects between the perception of visual motion and the concurrent production of hand movements. Two models, based on the notions of common coding and internal forward modeling, have been proposed to account for these phenomena. They predict that the size of the effects in perception and action should be monotonically related and vary with the amount of similarity between what is produced and perceived. These predictions were tested in four experiments in which participants were asked to make hand movements in certain directions while simultaneously encoding the direction of an independent stimulus motion. As expected, perceived directions were repelled by produced directions, and produced directions were repelled by perceived directions. However, contrary to the models, the size of the effects in perception and action did not covary, nor did they depend (as predicted) on the amount of perception–action similarity. We propose that such interactions are mediated by the activation of categorical representations.     

Principles and practices for communicating route knowledge

A series of experiments was conducted to examine the effect of several principle‐based practices hypothesized as being important in communicating route knowledge. Results indicated that remembering and following route directions were facilitated by the practice of (a) presenting the directions in correct temporal–spatial order, consistent with the principle of natural order, (b) concentrating information in statements concerned with choice points, consistent with the principle of referential determinacy, and, to some extent, (c) using spatial designations with which most listeners are facile, consistent with the principle of mutual knowledge. In all studies, women had more difficulty than men in following the route from verbal directions. Possible avenues for explaining this sex‐related difference are suggested. Copyright © 2000 John Wiley & Sons, Ltd.     

Gender and Regional Differences in Spatial Referents Used in Direction Giving

This study examined gender and regional differences in spatial referents used in giving route directions. In response to an Internet survey, participants (primarily white and highly educated) provided samples of route directions to a target destination in their home area. Only directions from those living in the United States were analyzed. Women referred more often than men to buildings as landmarks, whereas men referred more often than women to cardinal directions. Both women and men referred more often to cardinal directions if they reported that they lived in the Midwest/West than in the Northeast/South, or if they lived in areas where the roads were arranged in a gridlike pattern. The findings suggest that women and men differ in the type of spatial referents they use in giving directions, but that direction giving in both genders is affected by the environment in which they live.     

Detrended windowed (lag one) autocorrelation: A new method for distinguishing between event-based and emergent timing

Previous research on route directions largely considers the case when a knowledgeable route-giver conveys accurate information. In the real world, however, route information is sometimes inaccurate, and directions can lead navigators astray. We explored how participants respond to route directions containing ambiguities between landmarks and turn directions, forcing reliance on one or the other. In three experiments, participants read route directions (e.g., To get to the metro station, take a right at the pharmacy) and then selected from destinations on a map. Critically, in half of the trials the landmark (pharmacy) and turn (right) directions were conflicting, such that the participant had to make a decision under conditions of uncertainty; under these conditions, we measured whether participants preferentially relied upon landmark- versus direction-based strategies. Across the three experiments, participants were either provided no information regarding the source of directions (Experiment 1), or told that the source of directions was a GPS device (Experiment 2), or a human (Experiment 3). Without information regarding the source of directions, participants generally relied on landmarks or turn information under conditions of ambiguity; in contrast, with a GPS source participants relied primarily on turn information, and with a human source on landmark information. Results were robust across gender and individual differences in spatial preference. We discuss these results within the context of spatial decision-making theory and consider implications for the design and development of landmark-inclusive navigation systems.     

A Measure Of Similarity Between Individuals When Scoring Directions Of Variables Are Arbitrary

Holley and Guilford have proposed an index, G, originally intended for use in Q type factor analysis when scoring directions are arbitrary. G is appropriate for dichotomous data only. In this paper, a general measure is derived which is identical to G in the case of dichotomous data. The measure is approximately equal to the mean inter-person covariance when all permutations of scoring directions are considered. The measure is also closely connected both with component analysis of individual differences and with the condition of proportionality between two sets of observed values.     

Cognitive representation of auditory space in blind football experts

ObjectivesWe compared the mental representation of sound directions in blind football players, blind non-athletes and sighted individuals.DesignStanding blindfolded in the middle of a circle with 16 loudspeakers, participants judged whether the directions of two subsequently presented sounds were similar or not.MethodStructure dimensional analysis (SDA) was applied to reveal mean cluster solutions for the groups.ResultsHierarchical cluster analysis via SDA resulted in distinct representation structures of sound directions. The blind football players' mean cluster solution consisted of pairs of neighboring directions. The blind non-athletes also clustered the directions in pairs, but included non-adjacent directions. In the sighted participants' structure, frontal directions were clustered pairwise, the absolute back was singled out, and the side regions accounted for more directions.ConclusionsOur results suggest that the mental representation of egocentric auditory space is influenced by sight and by the level of expertise in auditory-based orientation and navigation.     

A phase-field model for deformation twinning

We propose a phase-field model for modeling microstructure evolution during deformation twinning. The order parameters are proportional to the shear strains defined in terms of twin plane orientations and twinning directions. Using a face-centered cubic Al as an example, the deformation energy as a function of shear strain is obtained using first-principle calculations. The gradient energy coefficients are fitted to the twin boundary energies along the twinning planes and to the dislocation core energies along the directions that are perpendicular to the twinning planes. The elastic strain energy of a twinned structure is included using the Khachaturyan's elastic theory. We simulated the twinning process and microstructure evolution under a number of fixed deformations and predicted the twinning plane orientations and microstructures.