Eric L G Legge

Publications (4)7.61 Total impact

• Source

  Available from: Patrick Schultheiss

  Article: Information content of visual scenes influences systematic search of desert ants.

  Patrick Schultheiss, Antoine Wystrach, Eric L G Legge, Ken Cheng
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  ABSTRACT: Many animals - including insects - navigate visually through their environment. Solitary foraging desert ants are known to acquire visual information from the surrounding panorama and use it to navigate along habitual routes or to pinpoint a goal like the nest. Returning foragers that fail to find the nest entrance engage in searching behaviour, during which they continue to use vision. The characteristics of searching behaviour have typically been investigated in unfamiliar environments. Here we investigated in detail the nest searching behaviour of Melophorus bagoti foragers within the familiar visual environment of their nest. First, by relating search behaviour to the information content of panoramic (360°) images, we found that searches were more accurate in visually cluttered environments. Second, as observed in unfamiliar visual surrounds, searches were dynamic and gradually expanded with time, showing that nest-pinpointing is not rigidly controlled by vision. Third, contrary to searches displayed in unfamiliar environments, searches observed here could be modelled as a single exponential search strategy, which is similar to a Brownian walk, and there was no evidence of a Lévy walk. Overall, our results revealed that searching behaviour is remarkably flexible and varies according to the relevance of information provided by the surrounding visual scenery.
  Journal of Experimental Biology 01/2013; 216(4):742-749. · 3.00 Impact Factor
• Article: Not using the obvious: desert ants, Melophorus bagoti, learn local vectors but not beacons in an arena.

  Eric L G Legge, Marcia L Spetch, Ken Cheng
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  ABSTRACT: Many ant species travel large distances to find food, sometimes covering distances that are up to one million times their body length. Even when these foraging trips follow convoluted paths, the ants usually find their way back to their nest with precision (Wehner et al. in J Exp Biol 199:129-140, 1996). Ants have been shown to use both compass cues in the sky (pattern of polarised light) and landmarks on Earth to return to their nest. We present two experiments conducted on a solitary foraging ant: Melophorus bagoti in their natural habitat in the central Australian desert. Ants were trained and tested in situ. We tested foragers' ability to exit a circular arena which provided an undifferentiated panorama. Artificial visual landmarks were located near a small exit. On tests in which path integration information was not available, foragers did not use artificial landmarks as beacons. Instead, they oriented in the learned exit direction, whether or not it pointed to the nest. We suggest that M. bagoti foragers learned a context-specific local vector when cued by the context of the circular arena. Our findings present the first evidence that M. bagoti foragers learn context-specific compass directions to chart their initial path home.
  Animal Cognition 11/2010; 13(6):849-60. · 3.09 Impact Factor
• Article: Pigeons' (Columba livia) hierarchical organization of local and global cues in touch screen tasks.

  Eric L G Legge, Marcia L Spetch, Emily R Batty
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  ABSTRACT: Redundant encoding of local and global spatial cues is a common occurrence in many species. However, preferential use of the each type of cue seems to vary across species and tasks. In the current study, pigeons (Columba livia) were trained in three experiments on a touch screen task which included redundant local positional cues and global spatial cues. Specifically, pigeons were required to choose the middle out of three choice squares, such that the position within the array provided local information and the location on the screen provided global information. In Experiment 1, pigeons were trained and tested on vertically aligned arrays. In Experiment 2, pigeons were trained and tested on horizontally aligned arrays, and in Experiment 3, pigeons were trained and tested with vertical, horizontal and diagonally aligned arrays. The results indicate that preference for cue type depends upon the type of spatial information being encoded. Specifically, on vertical and diagonally aligned arrays, pigeons preferred global cues, whereas on horizontally aligned arrays, pigeons preferred local cues.
  Behavioural processes 11/2008; 80(2):128-39. · 1.53 Impact Factor
• Article: The differential outcomes effect (DOE) in spatial localization: An investigation with adults

  Eric L.G. Legge, Marcia L. Spetch
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  ABSTRACT: We investigated whether search accuracy of adult humans could be enhanced using differential reward contingencies in landmark-based spatial tasks conducted on a computer screen. We found that search accuracy was significantly enhanced by differential outcomes in a conditional spatial search task, in which the landmark-to-goal relationship depended on a previously presented sample object (Experiment 4). In contrast, no significant differential outcomes effect (DOE) was seen in several other variations of spatial search tasks. We interpret the pattern of significant and non-significant results in terms of the information value of outcome expectancies. To our knowledge this is the first report of a DOE in a landmark-based spatial localization task and is one of only a few demonstrations that differential outcomes can enhance memory performance in normal functioning adults.
  Learning and Motivation.