title: Object similarity affects the perceptual strategy underlying invariant visual object recognition in rats.
abstract: In recent years, a number of studies have explored the possible use of rats as models of high-level visual functions. One central question at the root of such an investigation is to understand whether rat object vision relies on the processing of visual shape features or, rather, on lower-order image properties (e.g., overall brightness). In a recent study, we have shown that rats are capable of extracting multiple features of an object that are diagnostic of its identity, at least when those features are, structure-wise, distinct enough to be parsed by the rat visual system. In the present study, we have assessed the impact of object structure on rat perceptual strategy. We trained rats to discriminate between two structurally similar objects, and compared their recognition strategies with those reported in our previous study. We found that, under conditions of lower stimulus discriminability, rat visual discrimination strategy becomes more view-dependent and subject-dependent. Rats were still able to recognize the target objects, in a way that was largely tolerant (i.e., invariant) to object transformation; however, the larger structural and pixel-wise similarity affected the way objects were processed. Compared to the findings of our previous study, the patterns of diagnostic features were: (i) smaller and more scattered; (ii) only partially preserved across object views; and (iii) only partially reproducible across rats. On the other hand, rats were still found to adopt a multi-featural processing strategy and to make use of part of the optimal discriminatory information afforded by the two objects. Our findings suggest that, as in humans, rat invariant recognition can flexibly rely on either view-invariant representations of distinctive object features or view-specific object representations, acquired through learning.
authors: Visual Neuroscience Lab, International School for Advanced Studies (SISSA) Trieste, Italy.
authors: Federica B
authors: FB
authors: Rosselli
authors: Visual Neuroscience Lab, International School for Advanced Studies (SISSA) Trieste, Italy ; Department of Applied Science and Technology, Center for Computational Sciences, Politecnico di Torino Torino, Italy ; Human Genetics Foundation Torino, Italy.
authors: Alireza
authors: A
authors: Alemi
authors: Visual Neuroscience Lab, International School for Advanced Studies (SISSA) Trieste, Italy.
authors: Alessio
authors: A
authors: Ansuini
authors: Visual Neuroscience Lab, International School for Advanced Studies (SISSA) Trieste, Italy.
authors: Davide
authors: D
authors: Zoccolan
mesh_terms: D000818:Animals; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D051381:Rats / Q000502:physiology*; D020318:Rats, Long-Evans; D021641:Recognition, Psychology / Q000502:physiology*
keywords: invariance; object recognition; perceptual strategy; rodent vision; view-dependent; view-invariant