Visual multistability: influencing factors and analogies to auditory streaming

Sensory inputs can be ambiguous. A physically constant stimulus that induces several perceptual alternatives is called multistable. Many factors can influence perception. In this thesis I investigate factors that affect visual multistability. All presented studies use a pattern-component rivalry stimulus consisting of two gratings drifting in opposite directions (called the plaid stimulus). This induces an “integrated” perception of a moving plaid (the pattern) or a “segregated” perception of overlaid gratings (the components). One study (chapter 2) investigates parameter dependence of a plaid stimulus on perception, with particular emphasis on the first percept. Specifically, it addresses how the enclosed angle (opening angle) affects the perception at stimulus onset and during prolonged viewing. The effects that are shown persist even if the stimulus is rotated. On a more abstract level it is shown that percepts can influence each other over time (chapter 3) which emphasizes the importance of instructions and report mode. In particular, it relates to the decision which percepts are instructed to be reported at all as well as which percepts can be reported as separate entities and which are pooled into the same response option. A further abstract level (predictability of a stimulus change, chapter 5) shows that transferring effects from one modality to another modality (specifically from audition to vision) requires careful choice of stimulus parameters. In this context, we give considerations to the proposal for a wider usage of sequential stopping rules (SSR, chapter 4), especially in studies where effect sizes are hard to estimate a priori. This thesis contributes to the field of visual multistability by providing novel experimental insights into pattern-component rivalry and by linking these findings to data on sequential dependencies, to the optimization of experimental designs, and to models and results from another sensory modality.:Bibliographische Beschrei