Mugs and Plants: Object Semantic Knowledge Alters Perceptual Processing with Behavioral Ramifications

Abstract

Neural processing of objects with action associations recruits dorsal visual regions more than objects without such associations. We hypothesized that because the dorsal and ventral visual pathways have differing proportions of magno- and parvo-cellular input, there should be behavioral differences in perceptual tasks between manipulable and non-manipulable objects. This hypothesis was tested in adults across five experiments (Ns = 26, 26, 30, 25, 25) using a gap detection task, suited to the spatial resolution of parvocellular processing, and an object flicker discrimination task, suited to the temporal resolution of magnocellular processing. Directly predicted from the cellular composition of each pathway, a strong non-manipulable object advantage was observed in gap detection, and a small manipulable object advantage in flicker discrimination. Additionally, these effects are modulated by reducing object recognition through inversion and by suppressing magnocellular processing using red light. These results establish perceptual differences between objects dependent on semantic knowledge. Statement of RelevanceWhen we perceive an object, our knowledge of that object is brought to mind. Previous work has shown specifically that knowledge of object manipulability biases neural processing to areas of the brain in the parietal lobe which are relevant to motor processing. In this study we show that this neural bias, caused by knowledge of the object, has an effect on object perception. Using behavioral paradigms designed to take advantage of the specific response properties of neurons in the parietal and temporal object processing areas, we found that manipulable objects are perceived with higher temporal resolution while non-manipulable objects are perceived with higher spatial resolution. Our results demonstrate a specific neural mechanism by which prior knowledge affects current perception.