Twin mechanisms: Rapid scene recognition involves both feedforward and feedback processing.

The low spatial frequency (LSF) component of visual information rapidly conveyed coarse information for global perception, while the high spatial frequency (HSF) component delivered fine-grained information for detailed analyses. The feedforward theorists deemed that a coarse-to-fine process was sufficient for a rapid scene recognition. Based on the response priming paradigm, the present study aimed to deeply explore how different spatial frequency interacted with each other during rapid scene recognition. The response priming paradigm posited that as long as the prime slide could be rapidly recognized, the prime-target system was behaviorally equivalent to a feedforward system. Adopting broad spatial frequency images, experiment 1 revealed a typical response priming effect. But in experiment 2, when the HSF and the LSF components of the same pictures were separately presented, neither the LSF-to-HSF sequence nor the HSF-to-LSF sequence reproduced the response priming effect. These results demonstrated that LSF or HSF component alone was not sufficient for rapid scene recognition and, further, that the integration of different spatial frequency needed some early feedback loops. These findings supported that the local recurrent processing loops among early visual cortex was involved during rapid scene recognition.