On the Functional Significance of the P1 and N1 Effects to Illusory Figures in the Notch Mode of Presentation

The processing of Kanizsa figures have classically been studied by flashing the full “pacmen” inducers at stimulus onset. A recent study, however, has shown that it is advantageous to present illusory figures in the “notch” mode of presentation, that is by leaving the round inducers on screen at all times and by removing the inward-oriented notches delineating the illusory figure at stimulus onset. Indeed, using the notch mode of presentation, novel P1and N1 effects have been found when comparing visual potentials (VEPs) evoked by an illusory figure and the VEPs to a control figure whose onset corresponds to the removal of outward-oriented notches, which prevents their integration into one delineated form. In Experiment 1, we replicated these findings, the illusory figure was found to evoke a larger P1 and a smaller N1 than its control. In Experiment 2, real grey squares were placed over the notches so that one condition, that with inward-oriented notches, shows a large central grey square and the other condition, that with outward-oriented notches, shows four unconnected smaller grey squares. In response to these “real” figures, no P1 effect was found but a N1 effect comparable to the one obtained with illusory figures was observed. Taken together, these results suggest that the P1 effect observed with illusory figures is likely specific to the processing of the illusory features of the figures. Conversely, the fact that the N1 effect was also obtained with real figures indicates that this effect may be due to more global processes related to depth segmentation or surface/object perception

Geophysical Techniques for Plant, Soil, and Root Research Related to Sustainability

The sustainable management of human activities, from production to waste dis-posal and the cycling of finite resources is one of the great challenges of research for the coming decades, stemming from societal needs and the growing awareness of environmental mechanisms. Research on geophysical methods provides an inter-disciplinary approach to such challenges by addressing the need for techniques to assist in designing and moni-toring strategies for sustainability in agriculture and other environment-related sciences. In the past few decades technological advances have produced new tools or have improved existing techniques for near-surface geophysical investigation in a ro-bust, cost-effective and non-invasive way. Experimental results have proved that soil physical properties thus detected and mapped can be used as a proxy of physical, chemical and biological features relevant for the appropriate management of soils, based on their behavior, spatial variability and time-dynamics.. This chapter reviews principles of the techniques and reports selected research re-sults on environmental and agronomic research