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Mechanisms of object recognition: what we have learned from pigeons.

Soto FA, Wasserman EA - Front Neural Circuits (2014)

Bottom Line: The outcome is that pigeons are likely to be the non-primate species for which the computational mechanisms of object recognition are best understood.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA.

ABSTRACT
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.

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Schematic layout of a basic-level categorization trial (A) and a superordinate-level categorization trial (B) in experiments studying pigeons’ ability to flexibly categorize the same object at different hierarchical levels.
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Figure 2: Schematic layout of a basic-level categorization trial (A) and a superordinate-level categorization trial (B) in experiments studying pigeons’ ability to flexibly categorize the same object at different hierarchical levels.

Mentions: An important aspect of human categorization is that the same object can be flexibly categorized at several different hierarchical levels. For example, the photograph of a human can be categorized at the so-called “basic” level as a person, at the “superordinate” level as an animal, and at the “subordinate” level as “John”. Pigeons, too, have shown the ability to flexibly categorize the same objects (cars, chairs, flowers, and people) at different levels, depending on task demands (Figure 1D; Lazareva et al., 2004). The procedure used to train such flexible categories is illustrated in Figure 2. When the photograph of a human is presented together with four response keys, the pigeons learn to classify it at the basic level (Figure 2A), whereas when the photograph is presented together with two different response keys, the pigeons learn to classify it at the superordinate level of “natural object” (Figure 2B), comprising both people and flowers.


Mechanisms of object recognition: what we have learned from pigeons.

Soto FA, Wasserman EA - Front Neural Circuits (2014)

Schematic layout of a basic-level categorization trial (A) and a superordinate-level categorization trial (B) in experiments studying pigeons’ ability to flexibly categorize the same object at different hierarchical levels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4195317&req=5

Figure 2: Schematic layout of a basic-level categorization trial (A) and a superordinate-level categorization trial (B) in experiments studying pigeons’ ability to flexibly categorize the same object at different hierarchical levels.
Mentions: An important aspect of human categorization is that the same object can be flexibly categorized at several different hierarchical levels. For example, the photograph of a human can be categorized at the so-called “basic” level as a person, at the “superordinate” level as an animal, and at the “subordinate” level as “John”. Pigeons, too, have shown the ability to flexibly categorize the same objects (cars, chairs, flowers, and people) at different levels, depending on task demands (Figure 1D; Lazareva et al., 2004). The procedure used to train such flexible categories is illustrated in Figure 2. When the photograph of a human is presented together with four response keys, the pigeons learn to classify it at the basic level (Figure 2A), whereas when the photograph is presented together with two different response keys, the pigeons learn to classify it at the superordinate level of “natural object” (Figure 2B), comprising both people and flowers.

Bottom Line: The outcome is that pigeons are likely to be the non-primate species for which the computational mechanisms of object recognition are best understood.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus