Pigeons concurrently categorize photographs at both basic and superordinate levels (original) (raw)
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Categorical discrimination of objects and pictures by pigeons
Animal Learning & Behavior, 1992
With a three-choice instrumental discrimination procedure, pigeons were taught to distinguish small spherical objects from nonspherical objects. Spherical objects were defined as positive, nonspherical objects as negative. A device allowing an automatic presentation of the stimuli was employed. The subjects actually pecked the objects, and grain rewards were presented directly beside the correct objects. Acquisition was rapid, with the birds reaching a criterion of 80% correct choices within less than 150 trials. There was evidence that more than 200 objects were remembered individually over 3 months. Pigeons transferred the discrimination of sphericalJnonspherical objects to novel objects. The criteria by which the birds judged the sphericity of objects seemed to be similar to those applied by humans. They could apply the categorization in a relational manner and generalize it to apply to photographs and drawings of objects. The categorization competence was retained for at least 3 months.
Journal of Experimental Psychology: Animal Behavior Processes, 2012
A model proposing error-driven learning of associations between representations of stimulus properties and responses can account for many findings in the literature on object categorization by nonhuman animals. Furthermore, the model generates predictions that have been confirmed in both pigeons and people, suggesting that these learning processes are widespread across distantly related species. The present work reports evidence of a category-overshadowing effect in pigeons' categorization of natural objects, a novel behavioral phenomenon predicted by the model. Object categorization learning was impaired when a second category of objects provided redundant information about correct responses. The same impairment was not observed when single objects provided redundant information, but the category to which they belonged was uninformative, suggesting that this effect is different from simple overshadowing, arising from competition among stimulus categories rather than individual stimuli during learning.
Object recognition and object categorization in animals
Primate origins of human cognition and behavior, 2001
One of the most important attributes of cognitive activities in both human and nonhuman animals is the ability to recognize individual objects and to categorize a variety of objects that share some properties. Wild-living spider monkeys, for example, individually recognize their partners and a large number of other conspecifics quickly and accurately regardless of their highly variable spatial attitudes and also discriminate them from other species (T. Delius, personal observation). Object recognition and object categorization are both equally vital for most of the advanced animals. The retinal image of an object varies as a function of orientations, distances, lighting conditions, background scenes, and so forth at the time of viewing. Invariance operations are required for animals to identify objects despite variability of retinal stimulation. Observers may recognize the differences in orientation, location, size, and other aspects, but these differences do not obscure the identity of the objects. On the other hand, animals categorize a large number of individual objects into the same classes. There is little or no doubt that animals categorize natural objects sharing some properties, such as edible, water-offering, mateable, threatening, and so forth. The ability for animals to categorize objects enables them to learn about their environments economically with a drastic decrease in the stimulus information that they have to cope with. The processes that underlie object recognition and object categorization may well differ, but both require a common response to a variety of visual inputs. Pooling of a plurality of sensory inputs into fewer but more comprehensive signals is of great ecological relevance for animals. How and to what extent is such information pooling accomplished by animals?
Effects of stimulus manipulations on visual categorization in pigeons
Behavioural Processes, 2006
Four pigeons were previously trained . Pigeons concurrently categorize photographs at both basic and superordinate levels. Psychon. Bull. Rev. 11, 1111-1117 to classify color photographs into either their proper basic-level category (cars, chairs, flowers, or people) or a superordinate-level category (nominally natural or artificial). In Experiment 1, the same pigeons were shown either reflected or inverted versions of the training stimuli. Reflection had no effect on pigeons' classification behavior, whereas inversion impaired discrimination of all stimulus categories, except flowers, on the basic-level and superordinate-level tasks. Pixel matching analysis revealed that pattern matching played at most a minor role in the birds' categorization behavior. In Experiment 2, the pigeons were shown test stimuli that were either blurred or quartered and scrambled. Blurring impaired discrimination of cars, but had no effect on discrimination of people and flowers; scrambling impaired discrimination of people and flowers leaving discrimination of cars and chairs unaffected. These results suggest that categorization of flowers and people may be controlled primarily by the overall shape of the object rather than by local features, whereas categorization of cars and chairs may rely primarily on local features rather than the overall shape of the object.
Labeling and family resemblance in the discrimination of polymorphous categories by pigeons
Animal Cognition, 2011
Two experiments examined whether pigeons discriminate polymorphous categories on the basis of a single highly predictive feature or overall similarity. In the first experiment, pigeons were trained to discriminate between categories of photographs of complex real objects. Within these pictures, single features had been manipulated to produce a highly salient texture cue. Either the picture or the texture provided a reliable cue for discrimination during training, but in probe tests, the picture and texture cues were put into conflict. Some pigeons showed a significant tendency to discriminate on the basis of the picture cue (overall similarity or family resemblance), whereas others appeared to rely on the manipulated texture cue. The second experiment used artificial polymorphous categories in which one dimension of the stimulus provided a completely reliable cue to category membership, whereas three other dimensions provided cues that were individually unreliable but collectively provided a completely reliable basis for discrimination. Most pigeons came under the control of the reliable cue rather than the unreliable cues. A minority, however, came under the control of single dimensions from the unreliable set. We conclude that cue salience can be more important than cue reliability in determining what features will control behaviour when multiple cues are available.
Pigeons’ categorization may be exclusively nonanalytic
Psychonomic Bulletin & Review, 2011
Recent theoretical and empirical developments in human category learning have differentiated an analytic, rule-based system of category learning from a nonanalytic system that integrates information across stimulus dimensions. The researchers applied this theoretical distinction to pigeons' category learning. Pigeons learned to categorize stimuli varying in the tilt and width of their internal striping. The matched category problems had either a unidimensional (rule-based) or multidimensional (information-integration) solution. Whereas humans and nonhuman primates strongly dimensionalize these stimuli and learn rule-based tasks far more quickly than information-integration tasks, pigeons learned the two tasks equally quickly to the same accuracy level. Pigeons likely represent a cognitive system in which the commitment to dimensional analysis and category rules was not strongly made. Their performance suggests the character of the ancestral vertebrate categorization system from which that of primates emerged.
2012
Previous comparative work has suggested that the mechanisms of object categorization differ importantly for birds and primates. However, behavioral and neurobiological differences do not preclude the possibility that at least some of those mechanisms are shared across these evolutionarily distant groups. The present study integrates behavioral, neurobiological, and computational evidence concerning the "general processes" that are involved in object recognition in vertebrates. We start by reviewing work implicating error-driven learning in object categorization by birds and primates, and also consider neurobiological evidence suggesting that the basal ganglia might implement this process. We then turn to work with a computational model showing that principles of visual processing discovered in the primate brain can account for key behavioral findings in object recognition by pigeons, including cases in which pigeons' behavior differs from that of people. These results provide a proof of concept that the basic principles of visual shape processing are similar across distantly related vertebrate species, thereby offering important insights into the evolution of visual cognition. Keywords Object categorization. Object recognition. Error-driven learning. Hierarchical model. Feedforward processing. Comparative cognition. Avian vision. Pigeon. Computational model. Animal models. Visual cortex Many species must visually recognize and categorize objects to successfully adapt to their environments. Considerable comparative research has been conducted in object recognition, especially involving pigeons and people, whose visual systems have independently evolved from a common ancestor, from which their lineages diverged more than 300 million years ago. The results of behavioral studies have sometimes disclosed striking similarities between these species, and at other times have disclosed notable disparities, especially pointing toward a lower ability of pigeons to recognize transformed versions of familiar objects (for reviews, see Kirkpatrick, 2001; Spetch & Friedman, 2006). Similarly, the results of neurobiological studies have revealed both similarities and disparities in the structures that underlie visual object processing. The overall organization of the two visual systems is quite similar, with the most notable shared feature being their subdivision into parallel pathways. All amniotes (mammals, birds, and reptiles) have two main visual pathways from retina to telencephalon: the thalamofugal and tectofugal pathways (see Fig.
Mechanisms of object recognition: what we have learned from pigeons
Frontiers in Neural Circuits, 2014
Behavioral studies of object recognition in pigeons have been conducted for 50 years, yielding a large body of data. Recent work has been directed toward synthesizing this evidence and understanding the visual, associative, and cognitive mechanisms that are involved. The outcome is that pigeons are likely to be the non-primate species for which the computational mechanisms of object recognition are best understood. Here, we review this research and suggest that a core set of mechanisms for object recognition might be present in all vertebrates, including pigeons and people, making pigeons an excellent candidate model to study the neural mechanisms of object recognition. Behavioral and computational evidence suggests that error-driven learning participates in object category learning by pigeons and people, and recent neuroscientific research suggests that the basal ganglia, which are homologous in these species, may implement error-driven learning of stimulus-response associations. Furthermore, learning of abstract category representations can be observed in pigeons and other vertebrates. Finally, there is evidence that feedforward visual processing, a central mechanism in models of object recognition in the primate ventral stream, plays a role in object recognition by pigeons. We also highlight differences between pigeons and people in object recognition abilities, and propose candidate adaptive specializations which may explain them, such as holistic face processing and rule-based category learning in primates. From a modern comparative perspective, such specializations are to be expected regardless of the model species under study. The fact that we have a good idea of which aspects of object recognition differ in people and pigeons should be seen as an advantage over other animal models. From this perspective, we suggest that there is much to learn about human object recognition from studying the "simple" brains of pigeons.