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Factors affecting spatial association learning by hummingbirds

University of British Columbia

Numerous studies of learning in the laboratory have led to the general conclusion that animals associate cues and locations of response that are contiguous much more rapidly than ones that are spatially separated. Despite the fact that numerous animals readily use both contiguous and discontiguous cues to guide choices of good foraging locations in nature, there is no adequate explanation for the common observation of slow learning with discontiguous cues in standard laboratory learning tasks. Consequently, littl e is known about the process of spatial association learning. This thesis examined spatial association learning by rufous hummingbirds (Selasphorus rufus) in a series of six experiments. The first two experiments served to demonstrate that hummingbirds learn associations between red light cues and spatially separated feeders at virtually the same rate as they learn associations between cues contiguous with feeders. The spatial separation (2.5 cm) was small in those experiments but similar to separations between floral cues and locations of nectar in natural hummingbird- visited flowers. Later experiments, however, showed that hummingbirds can learn with considerably greater separations between cues and feeders (at least 12 cm). Rapid learning by the hummingbirds was likely due to the experimental situation, which imitated certain characteristics of their natural foraging environment, and to the experimental procedures, which allowed them much of their natural foraging behavior. These results with hummingbirds suggest that other animals should show improved learning with discontiguous cues if tested with learning problems analogous to those they encounter in their natural environments. The major goal of the rest of the thesis was to develop a theoretical framework for studying spatial association learning. The Gestalt principles of perceptual grouping were adopted as a candidate framework and experiments 3 and 4 tested hypotheses predicting specific responses to particular spatial arrangements of cues and response locations. The assumption underlying these hypotheses was that any factor which produced visual grouping of cues and their corresponding response locations should result in faster learning of the relationship between them. Experiment 3, based on the principle of spatial proximity, showed that birds performed well on three treatments in which strong visual grouping was predicted due to the proximity of cues and their feeders relative to the proximity of other cues and other feeders. They performed significantly less well on the treatment which predicted disruption of vi sual associations between cues and feeders due to relative proximity of other cues and other feeders. Experiment 4, based on the principles of connectedness and closure, showed that birds performed well on two treatments in which strong visual grouping within cue-feeder pairs was predicted due to the placement of visible features between each cue and its feeder. Complete lines linked cues with their feeders in one treatment and partial connections linked them on another, much as 'nectar guides' link the external surface cues of natural flowers with the nectar rewards that flowers contain . As predicted, birds learned faster on both of these arrays compared to one with no features between cues and feeders. Principles of Gestalt theory suggested the hypotheses and successfully predicted the results for each experiment whereas associative learning theory did not. Consequently, Gestalt theory should be considered as a useful framework for the study of spatial association learning. The final two experiments (5 and 6) each provided evidence that hummingbirds learned geometric spatial relationships as they foraged from the cue-feeder arrays. Other non-spatial learning mechanisms could have explained their success in the experiments of this study, but successful learning of a diagonal cue-feeder relationship and good performance following removal of visible connections between cues and feeders were consistent with the possibility that they learned spatial relationships.

Thesis/Dissertation

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2009-01-08

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http://hdl.handle.net/2429/3400

Zoology

University of British Columbia

UBCV

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