Multistabilità nell'auto-organizzazione percettiva: differenze individuali e correlati elettrocorticali

The main purpose of the present investigation was to evaluate individual differences in multistable perception in relation to electrocortical measures. Multistable figures, in fact, allow two or more equally plausible interpretations, without changes in their physical characteristics. Perceptual multistability has encountered a constant interest, over the years, from psychological researchers because it reflects the mechanisms of perceptual organization when the information from environment is vague or inconsistent. According to a constructivist view, an ambiguous figure is good investigating tool for highlighting the role of unconscious inferences, expectations, knowledge and attention in perception. Although there are many studies and researches on multistable perception, the neural mechanisms underlying the construction of the perceptual pattern are not yet completely understood. This is mainly due to the fact that the amount of experimental findings continues to bring evidence in favor of two basic theoretical hypotheses, without succeeding in fully support one or the other interpretation. One possible explanation focuses on passive bottom-up processes while another supports top-down influences. In a comprehensive and detailed review, Long and Toppino (2004) suggest a hybrid model attempting to overcome this debate. These authors, in fact, advise the investigators to consider interactions between low-level (sensory) and high-level (cognitive) processes in multistable perception. Event related potentials (ERPs) are optimal investigation tools for understanding the contribution of bottom-up and top-down mechanisms in multistability perception. In fact, these measures offer timing information that distinguish neural responses related to basic sensory features from those associated with mental representation (Eagleman, 2001). The goal of this doctoral thesis was, therefore, to investigate the relation between individual variability in perceptual switching behaviour and ERPs associated with multistable perception. These findings may provide new understanding on individual strategies in perceptual reorganization.