Perception of pictorial depth cues by pigeons

Abstract

Pigeons were trained to discriminate pictures of intact objects from pictures of objects in which both depth from shading and depth from perspective cues were manipulated. Depth from shading was manipulated either by scrambling or by removing three-dimensional shading cues. Depth from perspective was manipulated either by presenting pictures of objects with a two-dimensional outline (l.e., a square) or with a three-dimensional outline (Le., a cube). Transfer tests with novel images suggest that pigeons perceive and utilize both types of pictorial depth cues. The implications ofthese results for our understanding of picture perception in pigeons are discussed.Numerous studies in which the perceptual and cognitive abilities of pigeons were investigated have used pictorial displays (categorization: Edwards & Honig, 1987;Hernstein & Loveland, 1964;Wasserman, Kiedinger, & Bhatt;1988; object recognition: Kirkpatrick-Steger, Wasserman, & Biederman, 1996;Wasserman et al., 1996;White, Alsop, & Williams, 1993; and spatial relations: Spetch, Kelly, & Lechelt, 1998;Spetch & Wilkie, 1994;Wilkie, Willson, & MacDonald, 1992). Much of this research is predicated on the assumption that similar cognitive processes underlie responding to both two-dimensional (2-D) and three-dimensional (3-D) stimuli and that the third dimension is adequately represented by pictorial depth cues. However, the question of whether pictorial stimuli do in fact adequately represent 3-D objects and scenes for nonhuman animals has received comparatively little empirical investigation.Evidence from object-picture equivalence studies suggests that pigeons perceive pictures as representations of real objects. Pigeons trained to discriminate simple geometric objects transfer responding to photographs oftraining objects (Cabe, 1976;Lumsden, 1977), and pigeons trained to categorize real objects (food and junk items) transfer categorical responding to photographs of both training and novel objects (Deli us, 1992;Watanabe, 1993Watanabe, , 1997. Furthermore, birds have been shown to recognize pictures of conspecifics (Trillmich, 1976). Together, these studies suggest that, under certain conditions, nonhuman animals are capable of recognizing the equivalence between 3-D objects and their 2-D pictorial representations.Although object-picture equivalence studies are able to demonstrate transfer between objects and pictures, it is not certain to what extent these findings reflect a capacityThe research presented in this paper was also presented at the International Conference on Comparative Cognition in Melbourne, FL (March 1997). This research was supported by an operating grant from the Natural Sciences and Engineering Research Council of Canada to M.L.S. We thank D. Kelly for assistance with the research. Correspondence concerning this article should be addressed to M. L. Spetch, Department of Psychology, University of Alberta, Edmonton, AB, T6G 2E9 Canada (e-mail: mspetch@psych.ualberta.ca).to perceive three-dimensionality in 2-D displays, as compared with 2-D fe...

Recognition of static and dynamic images of depth-rotated human faces by pigeons

“…They concluded that the ability of these avian species to recognize equivalence between pictures and real objects is severely limited when a behavioral task requires a relatively precise correspondence. Although there is evidence that pigeons transfer discrimination from objects to pictures (e.g., Cabe, 1976;Delius, 1992;Watanabe, 1993) and that pigeons may have the ability to use 2-D cues to perceive three dimensionality (Cook & Katz, 1999;Reid & Spetch, 1998;Spetch, Kelly, & Lechelt, 1998), little is known about avian recognition of 2-D images of complex natural objects. In Experiments 2 and 3, we explored this issue.…”

Shape from shading in starlings (Sturnus vulgaris).

“…Because similar tests have not done with the pigeons, it is difficult to know if the starlings are similar or differ in this aspect. In general, experiments looking at the effects of shadows with pigeons have generally not found a strong contribution of this factor to shape perception (Cavoto & Cook, 2006; Reid & Spetch, 1998). Previous research in humans has shown that cast shadows are more important in identifying global spatial relationships of objects in a scene than making any contribution to shape perception (Mamassian, Knill, & Kersten, 1998), although that investigation focused on the perception of extrinsic cast shadows, instead of intrinsic cast shadows as tested here.…”

“…While prior studies with birds have employed a variety of methods, making generalization difficult, they suggest that some of these lighting cues are used in both natural and laboratory settings (Cavoto & Cook, 2006; Hershberger, 1970; Hess, 1950; Reid & Spetch, 1998; Rowland, Cuthill, Harvey, Speed, & Ruxton, 2008; Young, Peissig, Wasserman, & Biederman, 2001). …”

Discrimination of geons by pigeons: The effects of variations in surface depiction

“…The most surprising result in our study was the large decrement in accuracy that was caused by changes in the direction of lighting (in our personal observations of the program as it was presenting the stimuli, we usually failed to notice that the light-changed stimuli were not the original training stimuli). In another study exemplifying sensitivity to internal surface features, Reid and Spetch (1998) tested the pigeon's ability to use surface features to discriminate which of two two-dimensional images was a valid representation of a three-dimensional object. They found that pigeons can use internal surface variations in a way that is consistent with the classification of images as valid representations of three-dimensional objects, thus evidencing sensitivity to the configuration of these internal surface features.…”