Blocking of spatial learning between enclosure geometry and a local landmark

In a virtual environment, blocking of spatial learning to locate an invisible target was found reciprocally between a distinctively shaped enclosure and a local landmark within its walls. The blocking effect was significantly stronger when the shape of the enclosure rather than the landmark served as the blocking cue. However, the extent to which the landmark blocked enclosure-shape learning was not influenced by increasing the physical salience of the landmark. The outcomes are the first to suggest that cue-interaction effects, commonly found in human and animal contingency learning experiments, are also found in human spatial learning based on landmarks and enclosure walls. The data are discussed in terms of spatial reference frames.     

Strategies in landmark use by children, adults, and marmoset monkeys

Common marmosets (Callithrix jacchus jacchus), human children, and human adults learned to find a goal that was located in the center of a square array of four identical landmarks. The location of the landmark array and corresponding goal varied across trials, so the task could not be solved without using the landmark array. In Experiment 1, a matrix of discrete goal locations was presented and the landmarks surrounded and were adjacent to the correct location during training. After training, an expansion test was given in which the distance between landmarks was increased. Marmosets, children (ages 5–9), and adults all readily learned to use the landmarks to search accurately during training. On the expansion test, adults uniformly searched in the center of the array. Monkeys and children concentrated their searching near the landmarks rather than in the center. The monkeys, but not the children, searched more often on the directionally appropriate side of the landmarks than on other sides of the landmarks. In Experiment 2, children (ages 3–5) were trained with a continuous search space and with the goal farther from the landmarks so that a beaconing strategy rule could not be used. Several of the children failed to acquire the training task. Of those who learned to find the goal, three searched in the middle on expansion tests but most searched nearer to the landmarks. The “middle rule” strategy that is uniformly used by adult humans does not appear to be a preferred strategy for children or non-human primates.     

Learning about environmental geometry: an associative model

K. Cheng (1986) suggested that learning the geometry of enclosing surfaces takes place in a geometric module blind to other spatial information. Failures to find blocking or overshadowing of geometry learning by features near a goal seem consistent with this view. The authors present an operant model in which learning spatial features competes with geometry learning, as in the Rescorla-Wagner model. Relative total associative strength of cues at a location determines choice of that location and thus the frequencies of reward paired with each cue. The model shows how competitive learning of local features and geometry can appear to result in potentiation, blocking, or independence, depending on enclosure shape and kind of features. The model reproduces numerous findings from dry arenas and water mazes.     

The role of crawling and walking experience in infant spatial memory

This research explored infants' use of place learning and cue learning in a locomotor task across the transition from crawling to walking. Novice and expert crawling and walking infants were observed in a novel locomotor task-finding a hidden goal location in a large space. In Experiment 1, infants were tested with distal landmarks. Infants with fewer than 6 weeks of experience, either crawling or walking, could not find the goal location. All infants with more locomotor experience were more successful. Learning did not transfer across the transition to walking. In Experiment 2, novice and expert crawlers and walkers were tested with a direct landmark. Again, novice crawlers and walkers with fewer than 6 weeks of experience could not find the goal, whereas those with more experience could. Taken together, these findings suggest that infants' spatial learning is inextricably linked to mode of locomotion.     

Learned predictiveness training modulates biases towards using boundary or landmark cues during navigation

A number of navigational theories state that learning about landmark information should not interfere with learning about shape information provided by the boundary walls of an environment. A common test of such theories has been to assess whether landmark information will overshadow, or restrict, learning about shape information. Whilst a number of studies have shown that landmarks are not able to overshadow learning about shape information, some have shown that landmarks can, in fact, overshadow learning about shape information. Given the continued importance of theories that grant the shape information that is provided by the boundary of an environment a special status during learning, the experiments presented here were designed to assess whether the relative salience of shape and landmark information could account for the discrepant results of overshadowing studies. In Experiment 1, participants were first trained that either the landmarks within an arena (landmark-relevant), or the shape information provided by the boundary walls of an arena (shape-relevant), were relevant to finding a hidden goal. In a subsequent stage, when novel landmark and shape information were made relevant to finding the hidden goal, landmarks dominated behaviour for those given landmark-relevant training, whereas shape information dominated behaviour for those given shape-relevant training. Experiment 2, which was conducted without prior relevance training, revealed that the landmark cues, unconditionally, dominated behaviour in our task. The results of the present experiments, and the conflicting results from previous overshadowing experiments, are explained in terms of associative models that incorporate an attention variant.     

Beacon training in a water maze can facilitate and compete with subsequent room cue learning in rats

In Stage 1 of 4 experiments in which rats completed a water-maze blocking procedure, experimental groups were trained to use a predictive beacon (hanging above, connected to, or displaced from the platform) to find a submerged escape platform in the presence of predictive or irrelevant background cues and in the presence or absence of irrelevant landmarks. In Stage 2, a fixed beacon, landmarks, and background cues all predicted the platform location. A Room Test (landmarks and background cues only) showed that Stage 1 training with a fixed hanging beacon or the moving displaced beacon facilitated Stage 2 learning of predictive room cues for experimental relative to control subjects. In contrast, Stage 1 training with a moving pole beacon interfered with Stage 2 learning about predictive room cues relative to controls, whereas training with a fixed pole or moving hanging beacon had no effect. We conclude that multiple spatial learning processes influence locating an escape platform in the water maze.     

Transfer of spatial behaviour controlled by a landmark array with a distinctive shape

In two experiments, rats swam to a submerged platform in one corner of a rectangular or kite-shaped array created by four identical landmarks attached to the walls of a circular pool. After training in the rectangular array, rats expressed a preference for the corner in the kite-shaped array that was geometrically equivalent to where the platform was located previously. After training in either array, the removal of two landmarks from the rectangular array, or the landmark at the apex of the kite-shaped array, did not affect the control over searching exerted by the remaining landmarks. The results imply that rats use local rather than global spatial representations when searching for a hidden goal with reference to an array of landmarks.     

Preexposure effects in the spatial domain: Dissociation between latent inhibition and perceptual learning

In 4 experiments, rats were given intermixed or blocked preexposure to an array of landmarks that subsequently defined the location of a hidden goal in a Morris pool task. Previous research has shown that intermixed preexposure to pairs of adjacent landmarks retards learning whereas preexposure to individual landmarks facilitates subsequent learning (J. Prados, V. D. Chamizo, & N. J. Mackintosh, 1999). Accordingly, in Experiment 1, intermixed and blocked preexposure to pairs of adjacent landmarks was found to retard learning. In Experiment 2, however, a scheduling effect was found: Rats given intermixed preexposure to the individual landmarks learned faster than rats given blocked or no preexposure. Experiment 3 showed that intermixed (but not blocked) preexposure to pairs of landmarks resulted in a facilitatory effect when preexposure and test were carried out in different contexts. Experiment 4 replicated within a single experiment the main results observed in Experiments 1 and 3. This pattern of results suggests that intermixed preexposure engages learning processes other than latent inhibition that facilitate subsequent learning of the navigation task.     

Spatial integration of boundaries in a 3D virtual environment

Prior research, using two- and three-dimensional environments, has found that when both human and nonhuman animals independently acquire two associations between landmarks with a common landmark (e.g., LM1–LM2 and LM2–LM3), each with its own spatial relationship, they behave as if the two unique LMs have a known spatial relationship despite their never having been paired. Seemingly, they have integrated the two associations to create a third association with its own spatial relationship (LM1–LM3). Using sensory preconditioning (Experiment 1) and second-order conditioning (Experiment 2) procedures, we found that human participants integrated information about the boundaries of pathways to locate a goal within a three-dimensional virtual environment in the absence of any relevant landmarks. Spatial integration depended on the participant experiencing a common boundary feature with which to link the pathways. These results suggest that the principles of associative learning also apply to the boundaries of an environment.     

Blocking in the spatial domain with arrays of discrete landmarks.

A characteristic feature of associative conditioning is that learning a predictive relationship between two events can block later learning about an added event. It is not yet well established whether blocking occurs in the spatial domain or the circumstances in which it does. We now report, using rats trained to search for hidden food near landmarks in an open field arena, that blocking can occur in spatial learning. The animals noticed the added landmark at the start of the blocking phase and explored it, but either failed to incorporate it into their spatial map or developed a representation in which only some landmarks actually control behavior. Additionally, performance at asymptote was controlled by the shape of the landmark array rather than the individual landmarks comprising it, indicating that blocking in the spatial domain may represent a failure to alter the encoded geometry of a learned array.     

Multiple landmarks, the encoding of environmental geometry and the spatial logics of a dual brain

A series of place learning experiments was carried out in young chicks (Gallus gallus) in order to investigate how the geometry of a landmark array and that of a walled enclosure compete when disoriented animals could rely on both of them to re-orient towards the centre of the enclosure. A square-shaped array (four wooden sticks) was placed in the middle of a square-shaped enclosure, the two structures being concentric. Chicks were trained to ground-scratch to search for food hidden in the centre of the enclosure (and the array). To check for effects of array degradation, one, two, three or all landmarks were removed during test trials. Chicks concentrated their searching activity in the central area of the enclosure, but their accuracy was inversely contingent on the number of landmarks removed; moreover, the landmarks still present within the enclosure appeared to influence the shape of the searching patterns. The reduction in the number of landmarks affected the searching strategy of chicks, suggesting that they had focussed mainly on local cues when landmarks were present within the enclosure. When all the landmarks were removed, chicks searched over a larger area, suggesting an absolute encoding of distances from the local cues and less reliance on the relationships provided by the geometry of the enclosure. Under conditions of monocular vision, chicks tended to rely on different strategies to localize the centre on the basis of the eye (and thus the hemisphere) in use, the left hemisphere attending to details of the environment and the right hemisphere attending to the global shape.This contribution is part of the special issue “Animal Logics” (Watanabe and Huber 2006).     

Landmark Stability: Further Studies Pointing to a Role in Spatial Learning

Two experiments were conducted to investigate the possible role of landmark stability in spatial learning. Rats were trained to search in a large arena for food hidden at a consistent distance and direction from either a single radially symmetric landmark or an array of two landmarks. We varied the relative degree to which the landmark array and/or the cues of the training context predicted the location of food, without varying the conditional probability of food being available given either cue. Experiment 1 used vestibular disorientation to ensure control of search location by experimenter-controlled cues. The results showed that making either a single landmark or a cluster of two adjacent landmarks the sole spatial predictor of reward location reduced the accuracy of search compared to a condition where both the landmark array and context cues were reliable spatial predictors. Varying global landmark stability had no effect when training was conducted using an array of two landmarks located some distance from each other. Context cues, when tested alone, triggered very little searching in appropriate locations, and the absolute magnitude of control over search was insufficient to account for the superiority of stable landmarks. The better learning with a stable landmark, and the dependence of this effect on the geometrical arrangement of landmarks, points to the conditions of spatial learning involving additional principles to those of simple associative conditioning. Experiment 2 examined landmark stability using a single landmark and fixed directional cues in the absence of vestibular disorientation. This also revealed a relative advantage of landmark stability, but animals with a landmark that moved from trial to trial did show some evidence of learning. Context cues when tested alone had minimal influence. Parametric manipulation of landmark stability offers a novel way of influencing spatial learning and thus understanding better the process through which egocentric representations of perceived space are transformed into allocentric representations of the real world. The purpose of this paper is to describe two experiments concerned with identifying the psychological processes of allocentric spatial learning. The results point to the idea that landmark stability is an important factor in spatial learning. Specifically, they reveal that whether or not a landmark will be used for the purpose of representing the location of another object (including hidden objects) is influenced by whether it is perceived as geometrically stable with respect to at least one other landmark and/or certain geometric features of the environment. This phenomenon is relevant to the application of associative learning principles to the spatial domain.     

Evidence of blocking with geometric cues in a virtual watermaze

Three computer based experiments, testing human participants in a non-immersive virtual watermaze task, used a blocking design to assess whether two sets of geometric cues would compete in a manner described by associative models of learning. In stage 1, participants were required to discriminate between visually distinct platforms. In stage 2, additional spatial information was provided by the shape or the color of the walls of the pool. In a test trial, the platforms were removed and the spatial knowledge acquired regarding the position of the platform was assessed. Experimental groups were compared against control groups which did not receive stage 1 training. The unique color of the correct platform, in Experiments 1 and 3, disrupted learning about the colored walls but not the geometry of the pool. In Experiment 2, the correct platform was identifiable from its position within the three platform array. Learning the relative position of the correct platform within the array disrupted learning about its position relative to the geometry of the pool, but not to the colored walls. The results suggest that learning the position of a goal in relation to the geometry of the environment can be blocked but only by an alternative geometric cue.     

Tests for cognitive mapping in Clark's nutcrackers (Nucifraga columbiana)

In these experiments, the authors examined the nature of the spatial information that Clark's nutcrackers (Nucifraga columbiana) use during navigation and whether this information is represented in the form of a cognitive map. In Experiment 1, nutcrackers were able to use distal cues to locate a small hidden goal. In Experiments 2 and 3, nutcrackers were given the opportunity to develop a map of a room by viewing local subsets of the landmarks in the room at a goal during training. During transfer tests, nutcrackers were presented with a landmark panorama that was not previously seen at the goal. Of 3 nutcrackers that had learned the relationship between distal cues and the goal, 3 were able to locate the goal during transfer, indicating they may have developed a cognitive map. Experiments 4 and 5 suggest that the simpler mechanism of vector integration may have been used by some nutcrackers during the transfer tests.     

Flexible learning and use of multiple-landmark information by pigeons (Columba livia) in a touch screen-based goal searching task

Three touch screen-based experiments were conducted to investigate whether pigeons would learn to use configural information about a goal's location in relation to a multiple-landmark array. In Experiment 1, 4 pigeons (Columba livia) were trained to peck a computer monitor at a location that constituted the third vertex of a hypothetical triangle defined by 2 different landmarks. The landmarks appeared in 3 orientations during the training, and the pigeons' goal-searching ability easily transferred to the landmarks presented in 3 novel orientations. Each landmark was asymmetric, so we next examined whether the pigeons used (a) the small-scale, local orientation information that could be inferred from each landmark individually, or (b) the large-scale, configural information that could be inferred from the spatial arrangement of multiple landmarks taken as a whole. Even when each single landmark appeared by itself, the pigeons were able to locate the goal accurately, suggesting that the large-scale, configural information was not essential. However, when 1 landmark locally pointed to a location that was consistent with the triangular configuration and the other landmark locally pointed to a different location, the pigeons predominantly pecked at the configurally array-consistent location. These results suggest that the pigeons redundantly learned both the large-scale, configural strategy and the local, single-landmark strategy, but they mainly used the latter information, and used the former information solely to disambiguate conflicts when the 2 landmarks pointed toward different targets. Such flexible learning and use of redundant information may reflect the pigeons' adaptation to unstable wild environments during their evolutionary history.     

Multiple points of entry into a circular enclosure prevent place learning despite normal vestibular orientation and cue arrays: evidence for map resetting

This study identified sources of map orientation critical for successful spatial problem solving by rats of a plus maze embedded in water. Disorientation slowed, but it did not prevent acquisition of goal location. Use of a circular enclosure with multiple points of entry prevented reliable goal location. A single entry point enabled the rats to locate a fixed goal. A cue array within the enclosure was ineffective in providing orientation. These data suggest that stable map orientation can be derived from entry location when enclosure geometry is uniformative, but is not readily taken from cue arrays. They further suggest that map orientation is reset when rats enter an enclosure.     

Finding Where and Saying Where: Developmental Relationships Between Place Learning and Language in the First Year

The relationship between emergent spatial understanding in different cognitive domains, including navigation and language, has rarely been studied using methods that allow for the examination of individual differences. In this study the authors explored emergent place learning and its relationship to early spatial language, namely prepositions, in 16- to 24-month-old children. Children were tested using a spatial task adapted from the Morris water maze, and the MacArthur Communicative Development Inventory. In the place-learning task, children were placed in a circular enclosure and a puzzle was hidden under the floor at one location. Before each trial, children were disoriented and placed in the maze at a different starting position. Their search types and success at finding the puzzle were coded. As expected, older children demonstrated more spatial searches and better place-learning skills (finding the goal), as well as greater overall expressive vocabulary. Place learning and language did not correlate with each other once age was partialled, with one crucial exception: a theoretically predicted correlation between prepositions and goal localization.     

Effects of varying the amount of preexposure to spatial cues on a subsequent navigation task

In each of two experiments rats were preexposed to four compound landmarks (AX, BX, CX, and DX) one at a time; they were then trained to find a submerged platform located in a fixed position in a swimming pool using these same landmarks. When the preexposure was SHORT (4 sessions) it facilitated subsequent learning (a perceptual learning effect), whereas when rats were given a LONG preexposure phase (8 sessions) this facilitatory effect disappeared. EXTRA-LONG preexposure (16 sessions) reversed the facilitatory effect-that is to say, we observed retarded learning. The results show that rats' ability to navigate towards an invisible goal is affected by the length of their preexposure to the spatial cues that signal the location of the goal. These data are consistent with an associative analysis of the swimming pool navigation task.     

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.     

Orientation in the cuttlefish <Emphasis Type="Italic">Sepia officinalis</Emphasis>: response <Emphasis Type="Italic">versus</Emphasis> place learning

Several studies have demonstrated that mammals, birds and fish use comparable spatial learning strategies. Unfortunately, except in insects, few studies have investigated spatial learning mechanisms in invertebrates. Our study aimed to identify the strategies used by cuttlefish (Sepia officinalis) to solve a spatial task commonly used with vertebrates. A new spatial learning procedure using a T-maze was designed. In this maze, the cuttlefish learned how to enter a dark and sandy compartment. A preliminary test confirmed that individual cuttlefish showed an untrained side-turning preference (preference for turning right or left) in the T-maze. This preference could be reliably detected in a single probe trial. In the following two experiments, each individual was trained to enter the compartment opposite to its side-turning preference. In Experiment 1, distal visual cues were provided around the maze. In Experiment 2, the T-maze was surrounded by curtains and two proximal visual cues were provided above the apparatus. In both experiments, after acquisition, strategies used by cuttlefish to orient in the T-maze were tested by creating a conflict between the formerly rewarded algorithmic behaviour (turn, response learning) and the visual cues identifying the goal (place learning). Most cuttlefish relied on response learning in Experiment 1; the two strategies were used equally often in Experiment 2. In these experiments, the salience of cues provided during the experiment determined whether cuttlefish used response or place learning to solve this spatial task. Our study demonstrates for the first time the presence of multiple spatial strategies in cuttlefish that appear to closely parallel those described in vertebrates.