Temporally flexible feedback signal to foveal cortex for peripheral object recognition

Significance When subjects were asked to discriminate objects in the periphery, foveal visual noise presented at precise time windows following the peripheral object onset disrupted their performance. Further, this effect of foveal noise depends on task demand and stimulus features and primarily occurs for object tasks that involve spatial details. The time window, during which the noise is effective, can be shifted based on the amount of preprocessing of the peripheral objects, revealing the operation of temporally flexible feedback processing in the foveal cortex for peripheral object recognition. Recent studies have shown that information from peripherally presented images is present in the human foveal retinotopic cortex, presumably because of feedback signals. We investigated this potential feedback signal by presenting noise in fovea at different object–noise stimulus onset asynchronies (SOAs), whereas subjects performed a discrimination task on peripheral objects. Results revealed a selective impairment of performance when foveal noise was presented at 250-ms SOA, but only for tasks that required comparing objects’ spatial details, suggesting a task- and stimulus-dependent foveal processing mechanism. Critically, the temporal window of foveal processing was shifted when mental rotation was required for the peripheral objects, indicating that the foveal retinotopic processing is not automatically engaged at a fixed time following peripheral stimulation; rather, it occurs at a stage when detailed information is required. Moreover, fMRI measurements using multivoxel pattern analysis showed that both image and object category-relevant information of peripheral objects was represented in the foveal cortex. Taken together, our results support the hypothesis of a temporally flexible feedback signal to the foveal retinotopic cortex when discriminating objects in the visual periphery.