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Fragment-based learning of visual object categories in non-human primates.

Kromrey S, Maestri M, Hauffen K, Bart E, Hegdé J - PLoS ONE (2010)

Bottom Line: Recent research has shown that the visual system can use local, informative image fragments of a given object, rather than the whole object, to classify it into a familiar category.We have previously reported, using human psychophysical studies, that when subjects learn new object categories using whole objects, they incidentally learn informative fragments, even when not required to do so.However, the neuronal mechanisms by which we acquire and use informative fragments, as well as category knowledge itself, have remained unclear.

View Article: PubMed Central - PubMed

Affiliation: Brain and Behavior Discovery Institute, Medical College of Georgia, Augusta, Georgia, USA.

ABSTRACT
When we perceive a visual object, we implicitly or explicitly associate it with an object category we know. Recent research has shown that the visual system can use local, informative image fragments of a given object, rather than the whole object, to classify it into a familiar category. We have previously reported, using human psychophysical studies, that when subjects learn new object categories using whole objects, they incidentally learn informative fragments, even when not required to do so. However, the neuronal mechanisms by which we acquire and use informative fragments, as well as category knowledge itself, have remained unclear. Here we describe the methods by which we adapted the relevant human psychophysical methods to awake, behaving monkeys and replicated key previous psychophysical results. This establishes awake, behaving monkeys as a useful system for future neurophysiological studies not only of informative fragments in particular, but also of object categorization and category learning in general.

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Effect of M-scaling on categorization performance in Experiment 3.The animals performed a fragment-based categorization task where the sample stimulus in each trial was a fragment and the test stimulus was a whole object. All stimuli were presented at an eccentricity of 5° in the lower right quadrant. The performance of the animals for Main fragments is shown as a function of the fragment size. The performance for the Control fragments was at chance levels, as expected (not shown). For any given size, all stimuli, including all whole objects and fragments, were magnified by the same scaling factor. See Materials and Methods for details. The open arrow denotes the original size of the fragment (i.e., without magnification). The filled blue arrow denotes the M-scaled size appropriate for 5°. The dotted horizontal lines denote the performance of either animal when the stimuli were viewed foveally at their original, unmagnified size. Typical objects from the Main class and Control class are shown in the bottom right inset, with three selected Main fragments highlighted by blue squares on the object from the Main class.
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pone-0015444-g009: Effect of M-scaling on categorization performance in Experiment 3.The animals performed a fragment-based categorization task where the sample stimulus in each trial was a fragment and the test stimulus was a whole object. All stimuli were presented at an eccentricity of 5° in the lower right quadrant. The performance of the animals for Main fragments is shown as a function of the fragment size. The performance for the Control fragments was at chance levels, as expected (not shown). For any given size, all stimuli, including all whole objects and fragments, were magnified by the same scaling factor. See Materials and Methods for details. The open arrow denotes the original size of the fragment (i.e., without magnification). The filled blue arrow denotes the M-scaled size appropriate for 5°. The dotted horizontal lines denote the performance of either animal when the stimuli were viewed foveally at their original, unmagnified size. Typical objects from the Main class and Control class are shown in the bottom right inset, with three selected Main fragments highlighted by blue squares on the object from the Main class.

Mentions: To determine whether M-scaling can have a measurable ameliorative effect in such cases, we carried out Experiment 3 using a different, randomly chosen trio of categories in which the informative fragments were 20×20 pixels (or 0.36°×0.36°; Fig. 9). We essentially repeated Experiments 1 and 2 using these fragments. The dotted lines in Figure 9 denote the average performance of either animal for the Main fragments when the animals carried out the task foveally. Consistent with the results of Experiments 1 and 2, this performance was statistically indistinguishable from the animals' performance using whole objects (not shown).


Fragment-based learning of visual object categories in non-human primates.

Kromrey S, Maestri M, Hauffen K, Bart E, Hegdé J - PLoS ONE (2010)

Effect of M-scaling on categorization performance in Experiment 3.The animals performed a fragment-based categorization task where the sample stimulus in each trial was a fragment and the test stimulus was a whole object. All stimuli were presented at an eccentricity of 5° in the lower right quadrant. The performance of the animals for Main fragments is shown as a function of the fragment size. The performance for the Control fragments was at chance levels, as expected (not shown). For any given size, all stimuli, including all whole objects and fragments, were magnified by the same scaling factor. See Materials and Methods for details. The open arrow denotes the original size of the fragment (i.e., without magnification). The filled blue arrow denotes the M-scaled size appropriate for 5°. The dotted horizontal lines denote the performance of either animal when the stimuli were viewed foveally at their original, unmagnified size. Typical objects from the Main class and Control class are shown in the bottom right inset, with three selected Main fragments highlighted by blue squares on the object from the Main class.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2991334&req=5

pone-0015444-g009: Effect of M-scaling on categorization performance in Experiment 3.The animals performed a fragment-based categorization task where the sample stimulus in each trial was a fragment and the test stimulus was a whole object. All stimuli were presented at an eccentricity of 5° in the lower right quadrant. The performance of the animals for Main fragments is shown as a function of the fragment size. The performance for the Control fragments was at chance levels, as expected (not shown). For any given size, all stimuli, including all whole objects and fragments, were magnified by the same scaling factor. See Materials and Methods for details. The open arrow denotes the original size of the fragment (i.e., without magnification). The filled blue arrow denotes the M-scaled size appropriate for 5°. The dotted horizontal lines denote the performance of either animal when the stimuli were viewed foveally at their original, unmagnified size. Typical objects from the Main class and Control class are shown in the bottom right inset, with three selected Main fragments highlighted by blue squares on the object from the Main class.
Mentions: To determine whether M-scaling can have a measurable ameliorative effect in such cases, we carried out Experiment 3 using a different, randomly chosen trio of categories in which the informative fragments were 20×20 pixels (or 0.36°×0.36°; Fig. 9). We essentially repeated Experiments 1 and 2 using these fragments. The dotted lines in Figure 9 denote the average performance of either animal for the Main fragments when the animals carried out the task foveally. Consistent with the results of Experiments 1 and 2, this performance was statistically indistinguishable from the animals' performance using whole objects (not shown).

Bottom Line: Recent research has shown that the visual system can use local, informative image fragments of a given object, rather than the whole object, to classify it into a familiar category.We have previously reported, using human psychophysical studies, that when subjects learn new object categories using whole objects, they incidentally learn informative fragments, even when not required to do so.However, the neuronal mechanisms by which we acquire and use informative fragments, as well as category knowledge itself, have remained unclear.

View Article: PubMed Central - PubMed

Affiliation: Brain and Behavior Discovery Institute, Medical College of Georgia, Augusta, Georgia, USA.

ABSTRACT
When we perceive a visual object, we implicitly or explicitly associate it with an object category we know. Recent research has shown that the visual system can use local, informative image fragments of a given object, rather than the whole object, to classify it into a familiar category. We have previously reported, using human psychophysical studies, that when subjects learn new object categories using whole objects, they incidentally learn informative fragments, even when not required to do so. However, the neuronal mechanisms by which we acquire and use informative fragments, as well as category knowledge itself, have remained unclear. Here we describe the methods by which we adapted the relevant human psychophysical methods to awake, behaving monkeys and replicated key previous psychophysical results. This establishes awake, behaving monkeys as a useful system for future neurophysiological studies not only of informative fragments in particular, but also of object categorization and category learning in general.

Show MeSH