Abstract
Previous experiments have shown that conceptual information can be readily extracted from rapid serial visual presentations (RSVPs) of pictures (Potter, 1976; Potter et al., in press). Bar et al. (2006) hypothesized that a coarse, rapid magnocellular pathway transmitting low spatial frequencies (LSFs) to the orbitofrontal cortex provides possible identities for objects that are fed back to lower levels in the visual system, enabling such rapid perception. To test this hypothesis viewers detected named targets (e.g., smiling couple, harbor) in RSVP sequences of six grayscale pictures that were either unfiltered or filtered to provide only low spatial frequencies (LSFs). The pictures were new to the participants and were never repeated. The six pictures in each trial were presented for 13, 27, 53, or 80 ms each. When the target was named before the sequence, unfiltered pictures were detected more accurately than LSF pictures but both gave above-chance detection results at all durations. When the name was given afterward only the unfiltered pictures were detected above chance (except at 80 ms), suggesting that the LSF image was not able to activate the relevant concept without advance target information. Overall, the results raise critical questions about Bar et al.'s magnocellular feedback hypothesis, suggesting instead that feedforward processing (e.g., Serre et al., 2007) can be sufficient to activate conceptual representations without cortical feedback or prior knowledge of the target.
Meeting abstract presented at VSS 2014