Browsing by Author "Pavan, A."
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Item Open Access A comparison of equivalent noise methods in investigating local and global form and motion integration(Springer New York LLC, 2022-11-15) Pavan, A.; Contillo, A.; Koç, Şeyma; Kafalıgönül, Hulusi; Donato, R.; O’Hare, L.Static and dynamic cues within certain spatiotemporal proximity are used to evoke respective global percepts of form and motion. The limiting factors in this process are, first, internal noise, which indexes local orientation/direction detection, and, second, sampling efficiency, which relates to the processing and the representation of global orientation/direction. These parameters are quantified using the equivalent noise (EN) paradigm. EN has been implemented with just two levels: high and low noise. However, when using this simplified version, one must assume the shape of the overall noise dependence, as the intermediate points are missing. Here, we investigated whether two distinct EN methods, the 8-point and the simplified 2-point version, reveal comparable parameter estimates. This was performed for three different types of stimuli: random dot kinematograms, and static and dynamic translational Glass patterns, to investigate how constant internal noise estimates are, and how sampling efficiency might vary over tasks. The results indicated substantial compatibility between estimates over a wide range of external noise levels sampled with eight data points, and a simplified version producing two highly informative data points. Our findings support the use of a simplified procedure to estimate essential form-motion integration parameters, paving the way for rapid and critical applications to populations that cannot tolerate protracted measurements.Item Open Access Short-and long-term forms of neural adaptation: an ERP investigation of dynamic motion aftereffects(Elsevier, 2020) Akyüz, Sibel; Pavan, A.; Kaya, Utku; Kafalıgönül, HulusiAdaptation is essential to interact with a dynamic and changing environment, and can be observed on different timescales. Previous studies on a motion paradigm called dynamic motion aftereffect (dMAE) showed that neural adaptation can establish even in very short timescales. However, the neural mechanisms underlying such rapid form of neural plasticity is still debated. In the present study, short- and long-term forms of neural plasticity were investigated using dynamic motion aftereffect combined with EEG (Electroencephalogram). Participants were adapted to directional drifting gratings for either short (640 msec) or long (6.4 sec) durations. Both adaptation durations led to motion aftereffects on the perceived direction of a dynamic and directionally ambiguous test pattern, but the long adaptation produced stronger dMAE. In line with behavioral results, we found robust changes in the event-related potentials elicited by the dynamic test pattern within 64 e112 msec time range. These changes were mainly clustered over occipital and parietooccipital scalp sites. Within this time range, the aftereffects induced by long adaptation were stronger than those by short adaptation. Moreover, the aftereffects by each adaptation duration were in the opposite direction. Overall, these EEG findings suggest that dMAEs reflect changes in cortical areas mediating low- and mid-level visual motion processing. They further provide evidence that short- and long-term forms of motion adaptation lead to distinct changes in neural activity, and hence support the view that adaptation is an active time-dependent process which involves different neural mechanisms.