Spatial warping by oriented line detectors can counteract neural delays
- 1Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- 2Department of Psychiatry, Baylor College of Medicine, Houston, TX, USA
The slow speed of neural transmission necessitates that cortical visual information from dynamic scenes will lag reality. The “perceiving the present” (PTP) hypothesis suggests that the visual system can mitigate the effect of such delays by spatially warping scenes to look as they will in ~100 ms from now (Changizi, 2001). We here show that the Hering illusion, in which straight lines appear bowed, can be induced by a background of optic flow, consistent with the PTP hypothesis. However, importantly, the bowing direction is the same whether the flow is inward or outward. This suggests that if the warping is meant to counteract latencies, it is accomplished by a simple strategy that is insensitive to motion direction, and that works only under typical (forward-moving) circumstances. We also find that the illusion strengthens with longer pulses of optic flow, demonstrating motion integration over ~80 ms. The illusion is identical whether optic flow precedes or follows the flashing of bars, exposing the spatial warping to be equally postdictive and predictive, i.e., peri-dictive. Additionally, the illusion is diminished by cues which suggest the bars are independent of the background movement. Collectively, our findings are consistent with a role for networks of visual orientation-tuned neurons (e.g., simple cells in primary visual cortex) in spatial warping. We conclude that under the common condition of forward ego-motion, spatial warping counteracts the disadvantage of neural latencies. It is not possible to prove that this is the purpose of spatial warping, but our findings at minimum place constraints on the PTP hypothesis, demonstrating that any spatial warping for the purpose of counteracting neural delays is not a precise, on-the-fly computation, but instead a heuristic achieved by a simple mechanism that succeeds under normal circumstances.
Keywords: neural delays, neural latency, orientation tuning, prediction, postdiction, hering illusion, spatial cognition, time and motion studies
Citation: Vaughn DA and Eagleman DM (2013) Spatial warping by oriented line detectors can counteract neural delays. Front. Psychol. 4:794. doi: 10.3389/fpsyg.2013.00794
Received: 29 April 2013; Accepted: 08 October 2013;
Published online: 01 November 2013.
Copyright © 2013 Vaughn and Eagleman. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: David M. Eagleman, Departments of Neuroscience and Psychiatry, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA e-mail: firstname.lastname@example.org