Landmark use by Clark’s nutcrackers (Nucifraga columbiana): influence of disorientation and cue rotation on distance and direction estimates

Many species have been shown to encode multiple sources of information to orient. To examine what kinds of information animals use to locate a goal we manipulated cue rotation, cue availability, and inertial orientation when the food-storing Clark’s nutcracker (Nucifraga columbiana) was searching for a hidden goal in a circular arena. Three groups of birds were used, each with a different goal–landmark distance. As the distance between the goal and the landmark increased, nutcrackers were less accurate in finding the correct direction to the goal than they were at estimating the distance (Experiment 1). To further examine what cues the birds were using to calculate direction, the featural cues within the environment were rotated by 90° and the birds were either oriented when searching (Experiments 2 and 3) or disoriented (Experiment 3). In Experiment 4, all distinctive visual cues were removed (both internal and external to the environment), a novel point of entry was used and the birds were either oriented or disoriented. We found that disorienting the nutcrackers so that they could not use inertial cues did not influence the birds’ total search error. The birds relied heavily but not completely on cues within the environment, as rotating available cues caused them to systematically shift their search behavior. In addition, the birds also relied to some extent on Earth-based cues. These results show the flexible nature of cue use by the Clark’s nutcracker. Our study shows how multiple sources of spatial information may be important for extracting multiple bearings for navigation.     

Clark’s nutcrackers (<Emphasis Type="Italic">Nucifraga columbiana</Emphasis>) use gestures to identify the location of hidden food

Heterospecific cues, such as gaze direction and body position, may be an important source of information that an animal can use to infer the location of resources like food. The use of heterospecific cues has been largely investigated using primates, dogs, and other mammals; less is known about whether birds can also use heterospecific gestures. We tested six Clark’s nutcrackers in a two-way object-choice task using touch, point, and gaze cues to investigate whether these birds can use human gestures to find food. Most of the birds were able to use a touch gesture during the first trial of testing and were able to learn to use point and gaze (eyes and head alternation) cues after a limited number of trials. This study is the first to test a non-social corvid on the object-choice task. The performance of non-social nutcrackers is similar to that of more social and related corvids, suggesting that species with different evolutionary histories can utilize gestural information.     

Cognitive maps not used by humans (Homo sapiens) during a dynamic navigational task

To account for the impressive navigational ability of animals, some researchers have suggested that animals might use a cognitive map. Two groups of human participants (Homo sapiens) were tested for cognitive mapping using procedures similar to those used by B. M. Gibson and A. C. Kamil (2001). Participants who had to acquire spatial information about a hidden goal from the experimental contingencies alone showed patterns of search most like nutcrackers in the companion study (B. M. Gibson & A. C. Kamil, 2001). Surprisingly, postexperimental questionnaires revealed that most participants used an alternative strategy of vector integration rather than cognitive mapping during search for the hidden goal. The current study and its companion indicate that some simpler mechanisms of navigation are flexible enough to account for what appears to be map-based behavior in human and nonhuman species.     

Reorienting in images of a three-dimensional environment

Adult humans searched for a hidden goal in images depicting 3-dimensional rooms. Images contained either featural cues, geometric cues, or both, which could be used to determine the correct location of the goal. In Experiment 1, participants learned to use featural and geometric information equally well. However, men and women showed significant differences in their use of distant featural cues and the spontaneous encoding of geometric information when trained with features present. Transformation tests showed that participants could use either the color or the shape of the features independently to locate the goal. Experiment 2 showed that participants could use either configural or surface geometry when searching for the goal. However, their weighing of these geometric cues was dependent on initial training experience.     

Interference effects in the memory for serially presented locations in Clark's nutcrackers, Nucifraga columbiana

The authors tested the spatial memory of serially presented locations in Clark's nutcrackers (Nucifraga columbiana). Birds were serially presented with locations in an open room. The authors buried a seed in a sand-filled cup at each location and then tested nutcrackers for their memory for each location in the list by using the cluster method. For each item in the list, the authors opened a cluster of 6 holes. Accuracy was measured by how many tries were required for the bird to find the correct location within each cluster. In Experiments 1 and 2, the authors presented 2 lists of locations and found evidence for proactive and retroactive interference. Nutcrackers made errors by visiting the interfering list of locations during recovery of the target list. This finding demonstrates that nutcrackers are susceptible to proactive and retroactive interference during the recall of spatial information.     

Reorientation in a two-dimensional environment: I. Do adults encode the featural and geometric properties of a two-dimensional schematic of a room?

Adults searched for a goal in images of a rectangular environment. The goal's position was constant relative to featural and geometric cues, but the absolute position changed across trials. Participants easily learned to use the featural cues to find the target, but learning to use only geometric information was difficult. Transformation tests revealed that participants used the color and shape of distinct features to encode the goal's position. When the features at the correct and geometrically equivalent corners were removed, participants could use distant features to locate the goal. Accuracy remained above chance when a single distant feature was present, but the feature farthest from the goal yielded lower accuracy than one closer. Participants trained with features spontaneously encoded the geometric information. However, this representation did not withstand orientation transformations.     

Spatial memory of domestic dogs (Canis familiaris) for hidden objects in a detour task

Spatial memory of domestic dogs (Canis familiaris) for hidden objects was investigated via a visible displacement problem of object permanence with a detour paradigm. Experiment 1 showed that dogs were able to spontaneously locate a disappearing object in a detour situation. In Experiments 2 and 3, dead reckoning and allocentric spatial information were put in conflict. Results revealed that dogs simultaneously encoded both sources of information when they had to bypass an obstacle to locate a hidden object. Experiment 3 also revealed that, over the course of testing, dogs gradually learned to rely predominantly on allocentric cues when the detour involved several reorientations. The current study reveals that spatial memory of dogs for hidden objects in a detour task was guided by flexibility in processing spatial information. Dogs could simultaneously encode dead reckoning and allocentric information to locate a disappearing object and used them hierarchically according to the complexity of the detour they encountered in the environment.     

A comparative study of geometric rule learning by nutcrackers (Nucifraga columbiana), pigeons (Columba livia), and jackdaws (Corvus monedula)

Three avian species, a seed-caching corvid (Clark's nutcrackers; Nucifraga columbiana), a non-seed-caching corvid (jackdaws; Corvus monedula), and a non-seed-caching columbid (pigeons; Columba livia), were tested for ability to learn to find a goal halfway between 2 landmarks when distance between the landmarks varied during training. All 3 species learned, but jackdaws took much longer than either pigeons or nutcrackers. The nutcrackers searched more accurately than either pigeons or jackdaws. Both nutcrackers and pigeons showed good transfer to novel landmark arrays in which interlandmark distances were novel, but inconclusive results were obtained from jackdaws. Species differences in this spatial task appear quantitative rather than qualitative and are associated with differences in natural history rather than phylogeny.     

Use of visual, acoustic, and olfactory information during embedded invertebrate foraging in brown capuchins (Cebus apella)

Experiments were conducted to investigate which sensory cues are used by brown capuchins (Cebus apella) in embedded invertebrate foraging. The importance of visual, olfactory, and acoustic cues in such foraging was determined by presenting subjects with a stimulus log modified to block out given sensory cues. Experiment 1 was designed to investigate whether subjects could locate an invertebrate embedded in wood when only visual, acoustic, or olfactory information was available. Experiments 2 and 3 were designed to investigate extractive foraging behavior when two sensory cues were provided. It was hypothesized that the combination of visual and acoustic information would be necessary for subjects to successfully locate embedded invertebrates. Results indicated that subjects' performance was most successful when both visual and acoustic information was available.     

Rhesus monkeys use geometric and nongeometric information during a reorientation task

Rhesus monkeys (Macaca mulata) were subjected to a place finding task in a rectangular room perfectly homogeneous and without distinctive featural information. Results of Experiment 1 show that monkeys rely on the large-scale geometry of the room to retrieve a food reward. Experiments 2 and 3 indicate that subjects use also nongeometric information (colored wall) to reorient. Data of Experiments 4 and 5 suggest that monkeys do not use small angular cues but that they are sensitive to the size of the cues (Experiments 6, 7, and 8). Our findings strengthen the idea that a mechanism based on the geometry of the environment is at work in several mammalian species. In addition, the present data offer new perspectives on spatial cognition in animals that are phylogenetically close to humans. Specifically, the joint use of both geometric and landmark-based cues by rhesus monkeys tends to demonstrate that spatial processing became more flexible with evolution.     

Reorientation in a two-dimensional environment: II. Do pigeons (Columba livia) encode the featural and geometric properties of a two-dimensional schematic of a room?

Pigeons (Columba livia) searched for a hidden target area in images showing a schematic rectangular environment. The absolute position of the goal varied across trials but was constant relative to distinctive featural cues and geometric properties of the environment. Pigeons learned to use both of these properties to locate the goal. Transformation tests showed that pigeons could use either the color or shape of the features, but performance was better with color cues present. Pigeons could also use a single featural cue at an incorrect corner to distinguish between the correct corner and the geometrically equivalent corner; this indicates that they did not simply use the feature at the correct corner as a beacon. Interestingly, pigeons that were trained with features spontaneously encoded geometry. The encoded geometric information withstood vertical translations but not orientation transformations.     

Influence of distal and proximal cues in encoding geometric information

Vertebrates use geometric and featural information for spatial navigation. When both geometric and featural cues are available, animals can use a variety of spatial strategies based on this information. To examine the nature of these strategies, we manipulated the spatial relationship between a conspicuous cue and the position of the goal when goldfish (Carassius auratus) were searching for the exit of a rectangular environment with one distinctive wall. Two groups of fish were used, one with the distinctive wall close to the goal and the other with the distinctive wall on the other end of the enclosure. Results showed that fish encoded featural and geometric information in both conditions but the spatial relationship between the goal and the distinctive wall influences the characteristics of the encoding of the spatial cues and the strategy used to locate the goal. These results suggest that fish in both procedures use the local featural cues associated with the goal instead of the whole set of spatial cues as previous studies propose.     

An assessment of response, direction and place learning by rats in a water T-maze

Behavioral data suggest that distinguishable orientations may be necessary for place learning even when distal cues define different start points in the room and a unique goal location. We examined whether changes in orientation are also important in place learning and navigation in a water T-maze. In Experiment 1, rats were trained to locate a hidden platform and given a no-platform probe trial after 16 and 64 trials with the maze moved to a new position. Direction and response strategies were more prevalent than a place strategy. In Experiment 2, acquisition of place, response and direction strategies was assessed in a water T-maze that was moved between two locations during training. Rats were impaired on the place task when the maze was translated (moved to the L or R) but were successful when the maze was rotated across trials. These data are consistent with findings from appetitive tasks.     

Reorientation in diamond-shaped environments: encoding of features and angles in enclosures versus arrays by adult humans and pigeons (Columbia livia)

Although geometric reorientation has been extensively studied in numerous species, most research has been conducted in enclosed environments and has focused on use of the geometric property of relative wall length. The current studies investigated how angular information is used by adult humans and pigeons to orient and find a goal in enclosures or arrays that did not provide relative wall length information. In enclosed conditions, the angles formed a diamond shape connected by walls, whereas in array conditions, free-standing angles defined the diamond shape. Adult humans and pigeons were trained to locate two geometrically equivalent corners, either the 60° or 120° angles. Blue feature panels were located in the goal corners so that participants could use either the features or the local angular information to orient. Subsequent tests in manipulated environments isolated the individual cues from training or placed them in conflict with one another. In both enclosed and array environments, humans and pigeons were able to orient when either the angles or the features from training were removed. On conflict tests, female, but not male, adult humans weighted features more heavily than angular geometry. For pigeons, angles were weighted more heavily than features for birds that were trained to go to acute corners, but no difference in weighting was seen for birds trained to go to obtuse corners. These conflict test results were not affected by environment type. A subsequent test with pigeons ruled out an interpretation based on exclusive use of a principal axis rather than angle. Overall, the results indicate that, for both adult humans and pigeons, angular amplitude is a salient orientation cue in both enclosures and arrays of free-standing angles.     

Exploitation of pointing as a referential gesture in young children, but not adolescent chimpanzees

The ability of adolescent chimpanzees and 2- and 3-year-old children to use pointing gestures to locate hidden surprises was examined in two experiments. The results revealed that although young 2-year-old children appeared to have no difficulty extracting referential information from a pointing gesture (independent of gaze or distance cues) and spontaneously using it to search in specific locations, adolescent chimpanzees appeared to rely on cueconfiguration and distance-based rules. Thus, although these chimpanzees were trained to respond appropriately to the pointing gestures of a human by searching in a particular location, this ability did not easily generalize to situations in which the distance between the pointing hand and the location were more distal. Furthermore, even those chimpanzees that were able to generalize in this fashion appeared to use distance-based cues, not ones based on an appreciation of the internal attentional focus or mental referent of the experimenter as indicated by his pointing gesture.     

How rats perform spatial working memory tasks: Limitations in the use of egocentric and idiothetic working memory

Rats of the Dark Agouti strain were trained on delayed alternation under conditions that should encourage egocentric working memory. In two experiments a T-maze was set within a cross-maze so that different arms could be used for the sample and test runs. The maze had high opaque side-walls, and testing was conducted in low light levels so that distal visual cues might be eliminated. By rotating the maze 90° between the sample and choice run and by using two identical mazes set side by side it was possible to nullify other spatial strategies. Experiments 1 and 2 showed that rats preferentially used place information, intramaze cues, and direction cues, even though only egocentric or idiothetic (nonmatch-to-turn) working memory could successfully solve every trial. Rats were able to maintain an accurate sense of location within the maze even though distal cues were not visible and the animal was moved between the sample and choice runs. Experiment 2 confirmed that another rat strain (Long-Evans) shows the same learning profiles. Both experiments indicate that rats are very poor at using either egocentric or idiothetic information to alternate, and that retention delays as short as 10 s can eliminate the use of these forms of memory.     

How rats perform spatial working memory tasks: limitations in the use of egocentric and idiothetic working memory

Rats of the Dark Agouti strain were trained on delayed alternation under conditions that should encourage egocentric working memory. In two experiments a T-maze was set within a cross-maze so that different arms could be used for the sample and test runs. The maze had high opaque side-walls, and testing was conducted in low light levels so that distal visual cues might be eliminated. By rotating the maze 90° between the sample and choice run and by using two identical mazes set side by side it was possible to nullify other spatial strategies. Experiments 1 and 2 showed that rats preferentially used place information, intramaze cues, and direction cues, even though only egocentric or idiothetic (nonmatch-to-turn) working memory could successfully solve every trial. Rats were able to maintain an accurate sense of location within the maze even though distal cues were not visible and the animal was moved between the sample and choice runs. Experiment 2 confirmed that another rat strain (Long-Evans) shows the same learning profiles. Both experiments indicate that rats are very poor at using either egocentric or idiothetic information to alternate, and that retention delays as short as 10 s can eliminate the use of these forms of memory.     

Developmental Differences in Cognitive Control: Goal Representation and Maintenance During a Continuous Performance Task

The present study examined whether younger and older children differ in the use of the goal-related information in a continuous performance task (AX-CPT), and if so, whether those age differences are due to the ability to represent and/or maintain goal information. Experiment 1 compared third- and sixth-grade children in their ability to transform the identity of letter cues into goal representations, as well as to sustain those goal representations during a long (5,500 ms) cue-probe delay in the AX-CPT. Experiment 2 used a short cue-probe delay (1,000 ms) and thereby eliminated the demands of maintaining goal representations in working memory. In addition, Experiment 2 varied the level of demand that was placed on the ability to represent context information by varying the features of letter cues. The combined results of these experiments indicated that sixth graders were superior to third graders in cognitive control under conditions that placed demands on either the ability to represent or maintain goal-related information.     

Solving spatial tasks with unaligned layouts: the difficulty of dealing with conflicting information

Previous research has shown that preschool children have difficulty using relational information in spatial tasks. The present study investigates whether this difficulty is due, in part, to children's inability to deal with situations of conflict where both objective and egocentric cues are available and point to different responses. Two studies were conducted to compare performance in the presence versus absence of conflicting cues. In Study 1, 40 four-year-olds had to locate an object in a single layout presented from different perspectives. In Study 2, 39 four-year-olds had to transfer locational information between two unaligned layouts. The presence of conflict significantly affected children's performance in both studies. The results are discussed in the context of similar findings in other cognitive domains.