The role of posterior ventral stream areas for viewpoint-invariant object recognition

Object constancy is one of the most crucial mechanisms of the human visual system enabling viewpoint invariant object recognition. However, the neuronal foundations of object constancy are widely unknown. Research has shown that the ventral visual stream is involved in processing of various kinds of object stimuli and that several regions along the ventral stream are possibly sensitive to the orientation of an object in space. To systematically address the question of viewpoint sensitive object perception, we conducted a study with stroke patients as well as an fMRI experiment with healthy participants applying object stimuli in several spatial orientations, for example in typical and atypical viewing conditions. In the fMRI experiment, we found stronger BOLD signals and above-chance classification accuracies for objects presented in atypical viewing conditions in fusiform face sensitive and lateral occipito-temporal object preferring areas. In the behavioral patient study, we observed that lesions of the right fusiform gyrus were associated with lower performance in object recognition for atypical views. The complementary results from both experiments emphasize the contributions of fusiform and lateral-occipital areas to visual object constancy and indicate that visual object constancy is particularly enabled through increased neuronal activity and specific activation patterns for objects in demanding viewing conditions.

Functions of Same-Tracking

There are non-uniceptual same-tracking mechanisms, mechanisms that same-track not in order to implement storage of information about their targets, but merely as an aid to the identification of further things. Examples are the various mechanisms of perceptual constancy, self-relative location trackers, object-constancy mechanisms, and same-trackers for real categories. There are also several kinds of unicepts, hence, of unitrackers, procedural, substantive, attributive. What begins as a non-uniceptual same-tracker might or might not be redeployed to serve also as a procedural unitracker, or a procedural unitracker might be redeployed to serve also as a substance unitracker or an attribute unitracker. This is possible because the difference between affordances, substances, and attributes is not a basic ontological distinction but is relative to cognitive use.