Solving small spaces: investigating the use of landmark cues in brown capuchins (Cebus apella)

Some researchers have recently argued that humans may be unusual among primates in preferring to use landmark information when reasoning about some kinds of spatial problems. Some have explained this phenomenon by positing that our species’ tendency to prefer landmarks stems from a human-unique trait: language. Here, we test this hypothesis—that preferring to use landmarks to solve such tasks is related to language ability—by exploring landmark use in a spatial task in one non-human primate, the brown capuchin monkey (Cebus apella). We presented our subjects with the rotational displacement task, in which subjects attempt to relocate a reward hidden within an array of hiding locations which are subsequently rotated to a new position. Over several experiments, we varied the availability and the salience of a landmark cue within the array. Specifically, we varied (1) visual access to the array during rotation, (2) the type of landmark, (3) the consistency of the landmark qualities, and (4) the amount of exposure to the landmark. Across Experiments 1 through 4, capuchins did not successfully use landmarks cues, suggesting that non-linguistic primates may not spontaneously use landmarks to solve some spatial problems, as in this case of a small-scale dynamic spatial task. Importantly, we also observed that capuchins demonstrated some capacity to learn to use landmarks in Experiment 4, suggesting that non-linguistic creatures may be able to use some landmarks cues in similar spatial tasks with extensive training.     

Geometric modules in animals' spatial representations: a test with chicks (Gallus gallus domesticus)

Recent work has shown that in place-finding tasks rats rely on the geometric relations between the goal object and the shape of the environment. We tested young chickens (Gallus gallus domesticus) on similar tasks in a reference memory paradigm to determine whether differences exist between species in the ability to use geometric and nongeometric spatial information. The main findings were that chicks: (a) encoded and used both geometric and nongeometric (featural) information; (b) did not use the overall spatial arrangement of the features; (c) relied primarily on nongeometric cues when faced with contradictory information. Two mechanisms are evident in chicks' spatial representations: a metric frame for encoding the spatial arrangement of surfaces as surfaces and a cue-guidance system for encoding conspicuous landmarks near the target. The possibility of hierarchical organization and species differences in these two mechanisms are discussed.     

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.     

Learning your way around town: how virtual taxicab drivers learn to use both layout and landmark information

By having subjects drive a virtual taxicab through a computer-rendered town, we examined how landmark and layout information interact during spatial navigation. Subject-drivers searched for passengers, and then attempted to take the most efficient route to the requested destinations (one of several target stores). Experiment 1 demonstrated that subjects rapidly learn to find direct paths from random pickup locations to target stores. Experiment 2 varied the degree to which landmark and layout cues were preserved across two successively learned towns. When spatial layout was preserved, transfer was low if only target stores were altered, and high if both target stores and surrounding buildings were altered, even though in the latter case all local views were changed. This suggests that subjects can rapidly acquire a survey representation based on the spatial layout of the town and independent of local views, but that subjects will rely on local views when present, and are harmed when associations between previously learned landmarks are disrupted. We propose that spatial navigation reflects a hierarchical system in which either layout or landmark information is sufficient for orienting and wayfinding; however, when these types of cues conflict, landmarks are preferentially used.     

Wayfinding behavior and spatial knowledge of adults and children in a virtual environment: The role of landmarks

This study investigated the effect of different organizations of landmark-location pairings as fine-space information on wayfinding behavior and spatial knowledge on a total of 90 participants: 30 second graders, 30 sixth graders, and 30 adults. All participants had to find their way to a goal in a virtual environment with either randomized or categorical landmarks, or without any landmarks. Thereafter, they had to find the shortest way from the start position to the goal in two consecutive trials (wayfinding performance), and they had to solve a number of spatial knowledge tasks. The results showed that independent of their categorical function, the existence of landmarks influenced the way-finding performance of adults and children in the same way. Whereas the presence of landmarks had no effect on spatial survey knowledge, landmark knowledge itself was influenced by the categorical function of the landmarks presented. Moreover, second graders showed limited achievement compared to adults independent of the existence of landmarks. The main results implicate firstly that children at school age indeed are able to use landmark-location pairings as fine-space information like adults during learning an unknown environmental space, and secondly that a dissociation between wayfinding behavior and spatial knowledge might exist.     

The role of verbal labels in the judgment of orientation and location

In an earlier study it was found that judgments of right-left orientations and locations were more difficult than judgments of up-down only when spatial words were used in the tasks. Experiments are reported in which pictures of many objects were presented to eliminate the possibility that subjects in previous studies had used strategies specific to single-stimulus tasks. In experiment 1, right-left orientations were judged more slowly than up-down orientations both when the spatial words were used and when arbitrary letters replaced the spatial words. In experiment 2, judgments of the right-left locations of pictures took longer than judgments of their up-down locations only when spatial words were used in the task; the right-left difficulty was eliminated when arbitrary letters replaced the words. The differential effect of words and letters in location judgments seems to be due to the different coding strategies adopted by subjects under the two conditions. It is concluded that a right-left difficulty does not depend on the use of spatial terms: word and letter conditions yield different results only when the task permits different judgments to be made under the two conditions.     

Spatial memory in the real world: long-term representations of everyday environments

When people learn an environment, they appear to establish a principle orientation just as they would determine the “top” of a novel object. Evidence for reference orientations has largely come from observations of orientation dependence in pointing judgments: Participants are most accurate when asked to recall the space from a particular orientation. However, these investigations have used highly constrained encoding in both time-scale and navigational goals, leaving open the possibility that larger spaces experienced during navigational learning depend on a different organizational scheme. To test this possibility, we asked undergraduates to perform judgments of relative direction on familiar landmarks around their well-learned campus. Participants showed clear evidence for a single reference orientation, generally aligned along salient axes defined by the buildings and paths. This result argues that representing space involves the establishment of a reference orientation, a requirement that endures over repeated exposures and extensive experience.     

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.     

Cross-cultural differences in mental representations of time: evidence from an implicit nonlinguistic task

Across cultures people construct spatial representations of time. However, the particular spatial layouts created to represent time may differ across cultures. This paper examines whether people automatically access and use culturally specific spatial representations when reasoning about time. In Experiment 1, we asked Hebrew and English speakers to arrange pictures depicting temporal sequences of natural events, and to point to the hypothesized location of events relative to a reference point. In both tasks, English speakers (who read left to right) arranged temporal sequences to progress from left to right, whereas Hebrew speakers (who read right to left) arranged them from right to left, replicating previous work. In Experiments 2 and 3, we asked the participants to make rapid temporal order judgments about pairs of pictures presented one after the other (i.e., to decide whether the second picture showed a conceptually earlier or later time-point of an event than the first picture). Participants made responses using two adjacent keyboard keys. English speakers were faster to make "earlier" judgments when the "earlier" response needed to be made with the left response key than with the right response key. Hebrew speakers showed exactly the reverse pattern. Asking participants to use a space-time mapping inconsistent with the one suggested by writing direction in their language created interference, suggesting that participants were automatically creating writing-direction consistent spatial representations in the course of their normal temporal reasoning. It appears that people automatically access culturally specific spatial representations when making temporal judgments even in nonlinguistic tasks.     

The role of spatial memory and frames of reference in the precision of angular path integration

Angular path integration refers to the ability to maintain an estimate of self-location after a rotational displacement by integrating internally-generated (idiothetic) self-motion signals over time. Previous work has found that non-sensory inputs, namely spatial memory, can play a powerful role in angular path integration (Arthur et al., 2007, 2009). Here we investigated the conditions under which spatial memory facilitates angular path integration. We hypothesized that the benefit of spatial memory is particularly likely in spatial updating tasks in which one's self-location estimate is referenced to external space. To test this idea, we administered passive, non-visual body rotations (ranging 40°-140°) about the yaw axis and asked participants to use verbal reports or open-loop manual pointing to indicate the magnitude of the rotation. Prior to some trials, previews of the surrounding environment were given. We found that when participants adopted an egocentric frame of reference, the previously-observed benefit of previews on within-subject response precision was not manifested, regardless of whether remembered spatial frameworks were derived from vision or spatial language. We conclude that the powerful effect of spatial memory is dependent on one's frame of reference during self-motion updating.     

Time in the mind: using space to think about time

How do we construct abstract ideas like justice, mathematics, or time-travel? In this paper we investigate whether mental representations that result from physical experience underlie people's more abstract mental representations, using the domains of space and time as a testbed. People often talk about time using spatial language (e.g., a long vacation, a short concert). Do people also think about time using spatial representations, even when they are not using language? Results of six psychophysical experiments revealed that people are unable to ignore irrelevant spatial information when making judgments about duration, but not the converse. This pattern, which is predicted by the asymmetry between space and time in linguistic metaphors, was demonstrated here in tasks that do not involve any linguistic stimuli or responses. These findings provide evidence that the metaphorical relationship between space and time observed in language also exists in our more basic representations of distance and duration. Results suggest that our mental representations of things we can never see or touch may be built, in part, out of representations of physical experiences in perception and motor action.     

Cross-category structure in semantic memory

In Experiment I, subjects made similarity judgments about all 56 category terms listed in the Battig and Montague (1969) norms. These judgments were then subjected to a hierarchical clustering analysis. Experiment II demonstrated that the relations among the category labels are very similar to the relations among the high dominance exemplars of these categories. Experiment III showed that the distances between the category terms in the hierarchical clustering analysis could predict RTs in a same-different paradigm.     

The 36th Sir Frederick Bartlett Lecture: An associative analysis of spatial learning

The ability of animals to find important goals in their environment has been said to require a form of learning that is qualitatively different from that normally studied in the conditioning laboratory. Such spatial learning has been said to depend upon the construction of a global representation of the environment, and the acquisition of knowledge about the position of goals with reference to this representation is said to be unaffected by the presence of other cues or landmarks. To evaluate the first of these claims, experiments are described that investigated the extent to which the effects of training in one environment transfer to another. To evaluate the second claim, experiments are described that investigated whether cue competition effects normally found in conditioning studies can be found in spatial tasks. Overall, the results indicate that most of the phenomena of spatial learning can be explained by the principles of associative learning. The implications of the reported results for an understanding of the neural mechanisms of spatial learning are considered.     

Spatial egocentrism and the effect of an alternate frame of reference

The present study contrasted two possible explanations of spatial egocentrism in spatial perspective tasks. By one account children's judgments in perspectivetaking tasks are based on relations between the self (ego) and the target array. By the second account, children's judgments are based on relations between the target array and the larger spatial field. Sixty children in first, third, and fifth grades (ages 7, 9, and 11 years, respectively) solved both a standard and a modified version of a spatial perspective task. In the modified procedure, subjects observed a model of the experimental room that was rotated to appear as the actual room would appear to a hypothetical viewer. Using the model as an alternative frame of reference improved the performance of subjects in all age groups. In the standard procedure most errors were egocentric. In the modified procedure, subjects showed no systematic egocentric errors for rotations of 90 or 270°. The results supported the hypothesis that systematic egocentric errors are due to subjects realistically maintaining the relation of the array to the immediate spatial field, rather than maintaining the ego-array relation.     

Automatic activation of task-related representations in task shifting

Stimulus displays consisting of a target and a distractor can produce task conflicts when target and distractor are associated with different tasks. The present study examined whether these stimulus-induced task conflicts are affected by priming the irrelevant task or by increasing the salience of the distractor. In a series of three experiments, we employed a task-shifting paradigm in which subjects had to apply one of two judgments to either the global or the local level of a hierarchical stimulus. In each block, the target level and the judgment were either constant or mixed. Stimulus-induced judgment conflicts were measured by comparing performance for stimuli associated with two judgments and stimuli associated with only one. It turned out that only mixing the target level and not mixing the judgment increased the conflicts. These findings indicate that only the salience of the distractor modulates stimulus-induced conflicts.     

Differences in spatial knowledge acquired from maps and navigation

Models of the spatial knowledge people acquire from maps and navigation and the procedures required for spatial judgments using this knowledge are proposed. From a map, people acquire survey knowledge encoding global spatial relations. This knowledge resides in memory in images that can be scanned and measured like a physical map. From navigation, people acquire procedural knowledge of the routes connecting diverse locations. People combine mental simulation of travel through the environment and informal algebra to compute spatial judgments. An experiment in which subjects learned an environment from navigation or from a map evaluates predictions of these models. With moderate exposure, map learning is superior for judgments of relative location and straight-line distances among objects. Learning from navigation is superior for orienting oneself with respect to unseen objects and estimating route distances. With extensive exposure, the performance superiority of maps over navigation vanishes. These and other results are consonant with the proposed mechanisms.     

Indirect landmark use at 6 months of age in a spatial orientation task

It was hypothesized that 6-month-old infants may be able to use indirect landmarks to locate a goal if (a) the landmarks are sufficiently distinctive and (b) the goal location is between landmarks, rather than on the opposite side of the space as was used in earlier research. Six-month-old infants were tested in a peekaboo paradigm in which they had to turn to a target location after displacement to a novel position. Infants looked to the goal location significantly more in a beacon and an indirect landmarks condition relative to a control and a single landmark condition. These results are discussed in terms of current theories of spatial development.     

The orientation of young and older adults' mental representations of their home town with familiar and new landmarks

Familiarity with an environment produces refined mental representations in adults of all ages, but it is not clear whether these representations tend to have a north-up orientation and whether familiarity facilitates the learning of new spatial information, especially in ageing. Thirty-two young and 32 older adults studied a map of their home town that included familiar and new fictitious landmarks, then performed pointing tasks, some aligned with the cardinal points south–north (SN), and others counter-aligned, north–south (NS). A measure of visuo-spatial working memory (VSWM) and a questionnaire on pleasure in exploring were also administered. The results showed that performance was better when pointing SN than NS (alignment effect), whereas pointing performance for familiar landmarks was similar for SN and NS alignments (no alignment effect). No interaction involving age was found. VSWM emerged as a significant predictor of pointing performance. Spatial mental representations of familiar environments are elaborate and flexible as regards familiar landmarks, in both young and older adults; and a familiar layout does not seem to enhance older adults' spatial memory as regards new landmarks.