Abstract
It has been demonstrated that a decrease in stimulus visibility causes apparent time underestimation mediated by transient signals (1). Therefore, time compression should increase in peripheral vision as consequence of a decrease in stimulus visibility. We used parvocellular (P) and magnocellular (M)-biased flashes to test time perception in the range of milliseconds of a variable flash interval (VFI) at different eccentricities (0–48°). We found for both (M and P-biased flashes) an increase in time compression with eccentricity. Nevertheless, when stimulus visibility was “equalized” across the visual field, an increase in time compression was only found for M-biased stimuli. A second task was performed using the same P and M-biased flashes and VFI. Subjects reported if they perceived one or two successive stimuli. Results showed that the minimum VFI to avoid that the second flash was masked by the first one increased with eccentricity for the M-biased but not for the P-biased flashes in both -"standard” and “equalized"- conditions. Then we hypothesize that M pathway accounts for time underestimation and that its increasing with eccentricity could be an inherent property of the M system more than a result of a decrease in stimulus visibility. These results allow a better understanding of the temporal dynamics of conscious perception across the visual field and gives new clues about the role of M pathway in awareness.
Terao, M., et al. (2008). Reduction of stimulus visibility compresses apparent time intervals. Nat. Neurosci., 11(5), 541–542 (May).