Guest Editorial: On the Possibility of a Unifying Framework for Serial Dependencies

Guest Editorial: On the Possibility of a Unifying Framework for Serial Dependencies Guido Marco Cicchini Institute of Neuroscience, CNR, Pisa, Italy Arni Kristjansson Univerity of Iceland, Reykjavik, Iceland Serial effects in perception have been studied since the dawn of psychophysics. Color aftereffects greatly advanced the understanding of color vision in the 19th century, and motion aftereffects have intrigued perceptual scientists for centuries. Recent discoveries in visual attention and psychophysics have intensifed interest in such effects. The current consensus is that they are not curiosities but serve an important function and can be critical for understanding perception. In December 2015, a small group of vision scientists gathered for a 2-day workshop in Pisa to discuss these issues. The meeting (Serial Effects in Perception: Prediction, Priming, and Adaptation, December 11–12, 2014: www.pisavisionlab.org/sfx2014) brought together experts in varied types of serial effects: perceptual continuity, serial effects, priming, and adaptation. The abstracts of the meeting follow this introduction. The aim was to discuss the various findings in an attempt to find common features as well as distinguishing traits. In the first session, on perceptual serial dependencies, David Whitney presented evidence that both lower and higher level perceptual mechanisms utilize assimilative trial to trial information: Current perceptions are biased toward previous ones (Fischer & Whitney, 2014; Liberman, Fischer et al., 2014). Whitney also introduced the concept of a ‘‘continuity field’’: A zone in space and time where the brain looks for continuities. Although the extent of the continuity field might depend on the particular technique used for stimulus presentation and response, the concept seems useful to describe the benefits of serial effects: Things rarely change rapidly in the world so it might be beneficial to draw upon several snapshots overtime to represent the environment. Cicchini and Burr tackled a complementary issue. According to their work, a simple formula determines the optimal weight of current and past information: If two stimuli are similar, it is beneficial to give a consistent weight to past information and this reduces noise; however, if two stimuli are markedly different, the weight of the past information should be very small. In this way, one obtains an optimal mechanism that discounts sensory fluctuations, yet is responsive to abrupt changes (Burr & Cicchini, 2014). Such an adaptive Corresponding author: Guido Marco Cicchini, Institute of Neuroscience – CNR via Moruzzi, 1 56124, Pisa, Italy. Email: cicchini@in.cnr.it i-Perception