Abstract
Neuroimaging studies of object recognition have revealed that object processing is largely a result of computations within the dorsal and ventral visual streams. Each stream is differentially recruited depending on object identity. Objects with strong action associations (e.g., tools) recruit dorsal regions more than non-tool objects, which are more reliant on ventral processing. We hypothesized that if this differential functional recruitment is indeed meaningful, it should have behavioral consequences. Due to the relative proportions of magno- and parvo-cellular input to each stream, processing along the dorsal stream, such as when a tool is seen, should have higher temporal sensitivity, while processing along the ventral stream, such as when a non-tool is seen, should have higher spatial sensitivity. We test this hypothesis using two tasks: gap detection, testing the spatial resolution of the ventral parvocellular processing, and object flicker discrimination, testing the temporal resolution of the dorsal magnocellular processing. Across several experiments we show (1) a non-tool advantage in spatial resolution, (2) a tool advantage in temporal discrimination, (3) that this advantage is reduced by impeding object recognition through inversion, and (4) that this advantage diminishes when suppressing magnocellular processing with red light. Lastly, if these effects are due to expectation of object use, then the spatial and temporal resolution differences observed between tools and non-tools should be modulated by reachability. In virtual reality (VR), tools and non-tools are presented at variable depths, with the prediction that the perceptual differences should diminish with distance from the observer. These results demonstrate perceptual differences in object processing arising from differential recruitment of the two processing streams, such that tools, which recruit the more magnocellular dorsal stream regions have higher temporal resolution, and non-tools, which are reliant on the more parvocellular ventral stream regions, have higher spatial resolution.