The Emergence of Flexible Spatial Strategies in Young Children

The development of spatial navigation in children depends not only on remembering which landmarks lead to a goal location but also on developing strategies to deal with changes in the environment or imperfections in memory. Using cue combination methods, the authors examined 3-and 4-year-old children's memory for different types of spatial cues and the spatial strategies that they use when those cues are in conflict. Children were taught to search for a toy in 1 of 4 possible hiding locations. Children were then tested on transformations of the array of locations. The transformations dissociated the different types of cues by putting them in conflict with one another. The authors were especially interested in the use of a majority strategy, by which children choose to search in the location indicated by the greatest number of cue types rather than relying on a preferred cue type. Children's memory for spatial cues and their strategies varied both by age and by experimental setup. In Experiment 1, both 3-and 4-year-old children preferred to use the distinct landmarks coincident with the hiding locations over any other types of cues and showed no use of a majority strategy. However, in Experiment 2, when the coincident landmarks were moved adjacent to the hiding locations, both 3-and 4-year-old children preferred to search in the position of the hiding location relative to the array. Furthermore, 4-year-old children in Experiment 2 showed better memory for individual types of cues and the emergence of a majority strategy

Hierarchical Use of Cues in the Missing Object Recognition Task by Rats (Rattus norvegicus)

This study investigated rats’ preferences for using non-spatial and spatial cues in a missing-object recognition task. Rats were trained to find a sunflower seed under any one of four previously missing adjacent objects, the test array of a trial, after having found seeds under three of them in the ‘study’ array of that trial. On some trials the study and test arrays consisted of a different object at each baited food site and on other trials, of identical objects. A previously missing object\u27s position and orientation within its array and its global position within the large foraging chamber varied over trials but not within trials. Following training, rats received interspersed non- or partially rewarded probe trials with transformed test arrays of dissociated non-spatial (object-specific) and spatial cues on test array feeders. Results from these probe trials revealed that rats preferred to search for a missing object based first on its specific non-spatial features before searching for it based on its local spatial features; that is, its local position followed by its orientation, and finally based on its global position. This hierarchical sequence for using spatial cues was preserved under the identical-objects cueing condition. Rats reversed their preferences between object-specific and local position cues, however, when novel objects replaced the same four different objects in a supplementary experiment. We discussed the implications of these findings in terms of the influence of ecological- and context-dependent factors on information use or retrieval from animals’ visuo-spatial working memory

Innate heuristics and fast learning support escape route selection in mice

When faced with imminent danger, animals must rapidly take defensive actions to reach safety. Mice can react to threatening stimuli in ∼250 milliseconds and, in simple environments, use spatial memory to quickly escape to shelter. Natural habitats, however, often offer multiple routes to safety that animals must identify and choose from. This is challenging because although rodents can learn to navigate complex mazes, learning the value of different routes through trial and error during escape could be deadly. Here, we investigated how mice learn to choose between different escape routes. Using environments with paths to shelter of varying length and geometry, we find that mice prefer options that minimize path distance and angle relative to the shelter. This strategy is already present during the first threat encounter and after only ∼10 minutes of exploration in a novel environment, indicating that route selection does not require experience of escaping. Instead, an innate heuristic assigns survival value to each path after rapidly learning the spatial environment. This route selection process is flexible and allows quick adaptation to arenas with dynamic geometries. Computational modeling shows that model-based reinforcement learning agents replicate the observed behavior in environments where the shelter location is rewarding during exploration. These results show that mice combine fast spatial learning with innate heuristics to choose escape routes with the highest survival value. The results further suggest that integrating prior knowledge acquired through evolution with knowledge learned from experience supports adaptation to changing environments and minimizes the need for trial and error when the errors are costly

Morphological and Behavioral Traits Associated with Locomotion in Lizards

Morphology, locomotion, and behavior are co-adapted to optimize performance and ultimately fitness. Successfully navigating a complex environment is dictated by an animal’s locomotor behavior, and for some behaviors, its locomotor performance. The locomotor performance of an organism is directly related to the form and function of the structures involved in locomotion such that movement is efficient – that is, minimal loss of energy. The first chapter of this thesis focuses on the effects of obstacle placement and forelimb position on facultative bipedalism. Placing an obstacle beyond a lizard’s acceleration threshold did not affect the frequency of bipedal posture. Furthermore, the forelimb position of streamlined species is stereotyped during bipedal running, whereas the forelimb positions are varied in short stocky species. The second chapter investigates shape variation in the scapula among Phrynosomatid lizards across a gradient of species that vary in the use of horizontal to vertical locomotor planes. I determined that while global scapula shape is relatively conserved among lizards, localized changes occur at the muscle attachment sites used in vertical vs. horizontal locomotion. Furthermore, scapular shape in relation to habitat use is phylogenetically conserved with the exception of some Sceloporus species which diverged independently towards terrestrial locomotion

Foraging Fidelity as a Recipe for a Long Life: Foraging Strategy and Longevity in Male Southern Elephant Seals

Identifying individual factors affecting life-span has long been of interest for biologists and demographers: how do some individuals manage to dodge the forces of mortality when the vast majority does not? Answering this question is not straightforward, partly because of the arduous task of accurately estimating longevity in wild animals, and of the statistical difficulties in correlating time-varying ecological covariables with a single number (time-to-event). Here we investigated the relationship between foraging strategy and life-span in an elusive and large marine predator: the Southern Elephant Seal (Mirounga leonina). Using teeth recovered from dead males on îles Kerguelen, Southern Ocean, we first aged specimens. Then we used stable isotopic measurements of carbon () in dentin to study the effect of foraging location on individual life-span. Using a joint change-point/survival modelling approach which enabled us to describe the ontogenetic trajectory of foraging, we unveiled how a stable foraging strategy developed early in life positively covaried with longevity in male Southern Elephant Seals. Coupled with an appropriate statistical analysis, stable isotopes have the potential to tackle ecological questions of long standing interest but whose answer has been hampered by logistic constraints

Individual Confidence-Weighting and Group Decision-Making

Group-living species frequently pool individual information so as to reach consensus decisions such as when and where to move, or whether a predator is present. Such opinion-pooling has been demonstrated empirically, and theoretical models have been proposed to explain why group decisions are more reliable than individual decisions. Behavioural ecology theory frequently assumes that all individuals have equal decision-making abilities, but decision theory relaxes this assumption and has been tested in human groups. We summarise relevant theory and argue for its applicability to collective animal decisions. We consider selective pressure on confidence-weighting in groups of related and unrelated individuals. We also consider which species and behaviours may provide evidence of confidence-weighting, paying particular attention to the sophisticated vocal communication of cooperative breeders