Benchmarking the Basic Object Invariance Capacities of Pigeons and Jackdaws

A key challenge in visual object recognition is to generate stable recognition performance under changing viewing conditions. Past attempts to decipher the neural foundation of this ability have mainly focused on the primate ventral stream which creates a risk of confounding general mechanistic insights with layout-specific correlates of object invariance. To promote a synthesis of data beyond the mammalian clade, this study will explore neuronal correlates of object invariance in of pigeons (Columba livia) and jackdaws (Corvus monedula). The visual system of birds offers ideal conditions to explore the generality of neuronal principles as it displays an organization radically different from the ventral stream. In line with the behavioral protocol of a previous study in rats (Zoccolan et al., 2009), subjects will have to discriminate between two simple artificial 3D objects across identity-preserving transformations of viewing angle, viewing distance, and lighting condition. We expect pigeons will classify transformed objects at above-chance levels but also to display significant recognition costs in the face of transformations, based on previous literature and similar to performance patterns found in rats. In jackdaws, we predict a primate-like level of object invariance with substantially reduced transformation costs, as jackdaws likely utilize robust object representations for causal reasoning and advanced object manipulations in foraging or social contexts. Neuronally, we expect those species differences to be reflected in differential increases of object selectivity and tolerance from early to late stages of processing (ENTO, MVL, NI, NCL) as well as from distinct object-specific population activation patterns.