Optokinetic nystagmus (OKN) is a fundamental gaze-stabilising response in which eye movements attempt to compensate for the retinal slip caused by self-motion. The OKN response consists of a slow following movement made in the direction of stimulus motion interrupted by fast eye movements that are primarily made in the opposite direction. The timing and amplitude of these slow phases and quick phases are notably variable, but this variability is poorly understood. In this study I performed principal component analysis on OKN parameters in order to investigate how the eigenvectors and eigenvalues of the underlying components contribute to the correlation between OKN parameters over time. I found three categories of principal components that could explain the variance within each cycle of OKN, and only parameters from within a single cycle contributed highly to any given component. Differences found in the correlation matrices of OKN parameters appear to reflect changes in the eigenvalues of components, while eigenvectors remain predominantly similar across participants, and trials. I have developed a linear and stochastic model of OKN based on these results and demonstrated that OKN can be described as a 1st order Markov process, with three sources of noise affecting SP velocity, QP triggering, and QP amplitude. I have used this model to make some important predictions about the optokinetic reflex: the transient response of SP velocity, the existence of signal dependent noise in the system, the target position of QPs, and the threshold at which QPs are generated. Finally, I investigate whether the significant variability within OKN may represent adaptive control of explicit and implicit parameters. iii

INTRODUÇÃO: Os Potenciais Evocados Auditivos avaliam a atividade neuroelétrica da via auditiva desde o nervo auditivo até o córtex cerebral. A vectoeletronistagmografia permite analisar os canais semicirculares e/ou nervo vestibular inferior, verificando se existe comprometimento vestibular periférico ou central. A reabilitação vestibular é composta de exercícios físicos ativos e repetitivos de olhos, cabeça e corpo e/ou manobras específicas que visam diminuir a tontura e a instabilidade corporal, aumentar a estabilização no olhar, o controle postural e melhorar o bem-estar na realização das atividades do diaa- dia. Levando-se em conta a escassez de trabalhos na literatura que investiguem a via auditiva central em indivíduos com síndrome vestibular periférica e que sejam submetidos à reabilitação vestibular, torna-se importante conhecer o funcionamento do sistema auditivo central, desde o tronco encefálico até o córtex auditivo, em indivíduos com vestibulopatias periféricas. OBJETIVOS: caracterizar os potenciais evocados auditivos de curta, média e longa latências em indivíduos com vestibulopatias periféricas, bem como verificar a evolução destes potenciais e dos resultados obtidos no Dizziness Handicap Inventory (DHI) frente à reabilitação vestibular. MÉTODOS: Foram submetidos à avaliação eletrofisiológica da audição por meio dos potenciais evocados auditivos de tronco encefálico (PEATE), potencial evocado auditivo de média latência (PEAML) e potencial cognitivo (P300), bem como à aplicação do questionário DHI, antes e após reabilitação vestibular, 20 indivíduos com diagnóstico de Síndrome Vestibular Periférica Irritativa (SVPI) e 17 indivíduos com diagnóstico de Síndrome Vestibular Periférica Deficitária (SVPD), com idades entre 20 e 70 anos. RESULTADOS: Os resultados demonstraram que o grupo com SVPD apresentou maior porcentagem de resultados alterados no PEATE e PEAML. No que diz respeito aos tipos de alterações, pode-se observar no grupo com SVPD, alteração em tronco encefálico baixo no PEATE pré e pós RV; aumento das latências das ondas Na e Pa no PEAML pós RV, aumento da latência da onda Pa pré RV e efeito eletrodo para a amplitude Na- Pa pós RV. No grupo com SVPI, foi observada alteração do tipo outros no PEATE pré RV; aumento da latência da onda Pa no PEAML pré e pós RV e ambas as alterações para a amplitude Na-Pa pós RV. No estudo da evolução dos resultados pré e pós RV, pode-se observar maior porcentagem de resultados semelhantes para os três potenciais, em ambos os grupos avaliados. Na comparação do DHI pré e pós RV, ocorreram melhores resultados para os aspectos físico, emocional e funcional no grupo com SVPI e para os aspectos físico e emocional no grupo com SVPD. Tornam-se necessários mais estudos que avaliem a via auditiva central destes indivíduos para uma melhor caracterização dos achados eletrofisiológicos / INTRODUCTION: The auditory evoked potentials assess the neuroelectrical activity of the auditory pathway from the auditory nerve to the cerebral cortex. The vectoelectronystagmography analyzes the semicircular canals and/or inferior vestibular nerve, checking peripheral or central vestibular involvement. The vestibular rehabilitation therapy consists in active exercises and repetitive eyes exercises, head and body and/or specific maneuvers to reduce the dizziness and body instability, increase gaze stability and postural control and also improve well-being in daily activities. Taking into account the scarcity of studies in the literature that investigate the central auditory pathways in subjects who underwent vestibular rehabilitation therapy, it becames important to know the central auditory system from the brainstem to the auditory cortex, in subjects with peripheral vestibular disorders. OBJECTIVE: To characterize the auditory evoked potentials of short, middle and long latencies in subjects with peripheral vestibular disorders, as well as to evaluate the development of these potentials and the results obtained in the Dizziness Handicap Inventory (DHI) after vestibular rehabilitation therapy (VRT). METHODS: brainstem auditory evoked potential (BAEP), Auditory Middle- Latency Response (AMLR), cognitive potential (P300) and DHI were carried out in 20 subjects with Peripheral Vestibular Hyperfunction Syndrome and 17 subjects with Peripheral Vestibular Hypofunction Syndrome, aged between 20 and 70, before and after vestibular rehabilitation therapy. RESULTS: The results showed that the Peripheral Vestibular Hypofunction Syndrome group, presented higher percentage of altered results on BAEP and AMLR. Comparing the normal and altered results (qualitative analysis) between the groups in the BAEP, lower brainstem was predominantly observed in the Peripheral Vestibular Hypofunction Syndrome group before and after VRT; increased latencies of Na and Pa waves in AMLR after VRT, incresead latency of Pa wave in AMLR before VRT and electrode effect to the Na-Pa amplitude after VRT. The alteration predominantly observed in the Peripheral Vestibular Hyperfunction Syndrome group, was the other type one before VRT; increased latency of Pa wave in AMLR before and after VRT and both changes to the Na-Pa amplitude after VRT. In the study of the evolution before and after VRT, it was observed a higher percentage of similar results for the three potentials in both groups. Comparing results before and after VRT, the DHI greatest improvement occurred for the physical, emotional and functional aspects in the Peripheral Vestibular Hyperfunction Syndrome group and for the physical and emotional aspects in the Peripheral Vestibular Hypofunction Syndrome group. Further studies that evaluate the central auditory pathway of individuals with peripheral vestibular syndrome are needed to better characterize the electrophysiological findings

Made available in DSpace on 2015-07-22T20:49:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-26 / Objetivo: comparar o nistagmo pós-calórico da prova com ar a 50 e 24°C com o da prova com água a 44 e 30°C. Método: estudo transversal controlado em 40 indivíduos hígidos, sem sintomas e sinais de alteração da audição e do equilíbrio corporal e que não estavam fazendo uso de medicamentos. Os indivíduos foram instruídos quanto ao preparo do exame e submetidos à avaliação vestibular incluindo a prova calórica com ar a 50 e 24°C e com água a 44 e 30°C. Os mesmos foram distribuídos de forma aleatória em dois grupos, segundo a ordem de estimulação calórica, ora iniciando com ar, ora com água. Resultados: À comparação das provas com ar e com água, não houve diferença significante entre os valores da velocidade angular da componente lenta (VACL) do nistagmo pós-calórico quanto à ordem de realização das estimulações, entre as orelhas e entre os valores de predomínio labiríntico e de preponderância direcional. Os valores de VACL foram maiores nas estimulações com água do que com ar (p=0,008; p<0,001). A temperatura fria evocou respostas mais intensas do que a temperatura quente nas provas com ar e com água (p<0,001). Conclusão: A prova calórica com água apresenta valores de VACL maiores do que a prova calórica com ar, mas ambas as provas apresentam semelhança nos valores da VACL maiores na temperatura fria e nos resultados dos valores relativos de predomínio labiríntico e preponderância direcional do nistagmo. / Purpose: to compare the nystagmus response in air (50°C/24°C) and water (44°C/30°C) caloric tests. Method: controlled cross-sectional study in 40 healthy individuals without any symptoms or signs of either hearing or balance disorders who were not making use of any medications. The individuals underwent an otoneurological evaluation, including air (50°C/24°C) and water (44°C/30°C) caloric tests. Results: Comparing air and water caloric tests, no significant difference was found among the values of slow-phase velocity post-caloric nystagmus regarding the stimulation order, between ears and between the values of unilateral weakness and directional preponderance. Slow-phase velocity values were higher in water than in air stimulation (p=0.008, p<0.001). Cold stimulation evoked more intense responses than warm stimulation in both air and water tests (p<0.001). Conclusion: In air (50°C/24°C) and water (44°C/30°C) caloric tests, the post-caloric nystagmus is similar in terms of slow-phase velocity values in both ears, higher responses in the cold temperature, unilateral weakness and directional preponderance results but it is different with regard to slow-phase velocity values which are higher in water test. / TEDE / BV UNIFESP: Teses e dissertações

INTRODUÇÃO: Os Potenciais Evocados Auditivos avaliam a atividade neuroelétrica da via auditiva desde o nervo auditivo até o córtex cerebral. A vectoeletronistagmografia permite analisar os canais semicirculares e/ou nervo vestibular inferior, verificando se existe comprometimento vestibular periférico ou central. A reabilitação vestibular é composta de exercícios físicos ativos e repetitivos de olhos, cabeça e corpo e/ou manobras específicas que visam diminuir a tontura e a instabilidade corporal, aumentar a estabilização no olhar, o controle postural e melhorar o bem-estar na realização das atividades do diaa- dia. Levando-se em conta a escassez de trabalhos na literatura que investiguem a via auditiva central em indivíduos com síndrome vestibular periférica e que sejam submetidos à reabilitação vestibular, torna-se importante conhecer o funcionamento do sistema auditivo central, desde o tronco encefálico até o córtex auditivo, em indivíduos com vestibulopatias periféricas. OBJETIVOS: caracterizar os potenciais evocados auditivos de curta, média e longa latências em indivíduos com vestibulopatias periféricas, bem como verificar a evolução destes potenciais e dos resultados obtidos no Dizziness Handicap Inventory (DHI) frente à reabilitação vestibular. MÉTODOS: Foram submetidos à avaliação eletrofisiológica da audição por meio dos potenciais evocados auditivos de tronco encefálico (PEATE), potencial evocado auditivo de média latência (PEAML) e potencial cognitivo (P300), bem como à aplicação do questionário DHI, antes e após reabilitação vestibular, 20 indivíduos com diagnóstico de Síndrome Vestibular Periférica Irritativa (SVPI) e 17 indivíduos com diagnóstico de Síndrome Vestibular Periférica Deficitária (SVPD), com idades entre 20 e 70 anos. RESULTADOS: Os resultados demonstraram que o grupo com SVPD apresentou maior porcentagem de resultados alterados no PEATE e PEAML. No que diz respeito aos tipos de alterações, pode-se observar no grupo com SVPD, alteração em tronco encefálico baixo no PEATE pré e pós RV; aumento das latências das ondas Na e Pa no PEAML pós RV, aumento da latência da onda Pa pré RV e efeito eletrodo para a amplitude Na- Pa pós RV. No grupo com SVPI, foi observada alteração do tipo outros no PEATE pré RV; aumento da latência da onda Pa no PEAML pré e pós RV e ambas as alterações para a amplitude Na-Pa pós RV. No estudo da evolução dos resultados pré e pós RV, pode-se observar maior porcentagem de resultados semelhantes para os três potenciais, em ambos os grupos avaliados. Na comparação do DHI pré e pós RV, ocorreram melhores resultados para os aspectos físico, emocional e funcional no grupo com SVPI e para os aspectos físico e emocional no grupo com SVPD. Tornam-se necessários mais estudos que avaliem a via auditiva central destes indivíduos para uma melhor caracterização dos achados eletrofisiológicos / INTRODUCTION: The auditory evoked potentials assess the neuroelectrical activity of the auditory pathway from the auditory nerve to the cerebral cortex. The vectoelectronystagmography analyzes the semicircular canals and/or inferior vestibular nerve, checking peripheral or central vestibular involvement. The vestibular rehabilitation therapy consists in active exercises and repetitive eyes exercises, head and body and/or specific maneuvers to reduce the dizziness and body instability, increase gaze stability and postural control and also improve well-being in daily activities. Taking into account the scarcity of studies in the literature that investigate the central auditory pathways in subjects who underwent vestibular rehabilitation therapy, it becames important to know the central auditory system from the brainstem to the auditory cortex, in subjects with peripheral vestibular disorders. OBJECTIVE: To characterize the auditory evoked potentials of short, middle and long latencies in subjects with peripheral vestibular disorders, as well as to evaluate the development of these potentials and the results obtained in the Dizziness Handicap Inventory (DHI) after vestibular rehabilitation therapy (VRT). METHODS: brainstem auditory evoked potential (BAEP), Auditory Middle- Latency Response (AMLR), cognitive potential (P300) and DHI were carried out in 20 subjects with Peripheral Vestibular Hyperfunction Syndrome and 17 subjects with Peripheral Vestibular Hypofunction Syndrome, aged between 20 and 70, before and after vestibular rehabilitation therapy. RESULTS: The results showed that the Peripheral Vestibular Hypofunction Syndrome group, presented higher percentage of altered results on BAEP and AMLR. Comparing the normal and altered results (qualitative analysis) between the groups in the BAEP, lower brainstem was predominantly observed in the Peripheral Vestibular Hypofunction Syndrome group before and after VRT; increased latencies of Na and Pa waves in AMLR after VRT, incresead latency of Pa wave in AMLR before VRT and electrode effect to the Na-Pa amplitude after VRT. The alteration predominantly observed in the Peripheral Vestibular Hyperfunction Syndrome group, was the other type one before VRT; increased latency of Pa wave in AMLR before and after VRT and both changes to the Na-Pa amplitude after VRT. In the study of the evolution before and after VRT, it was observed a higher percentage of similar results for the three potentials in both groups. Comparing results before and after VRT, the DHI greatest improvement occurred for the physical, emotional and functional aspects in the Peripheral Vestibular Hyperfunction Syndrome group and for the physical and emotional aspects in the Peripheral Vestibular Hypofunction Syndrome group. Further studies that evaluate the central auditory pathway of individuals with peripheral vestibular syndrome are needed to better characterize the electrophysiological findings

Les manifestations neuro-ophtalmologiques, observées dans la sclérose en plaques sont parfaitement déterminées à l'heure actuelle. Cependant, l'aspect chronique des troubles visuels résultants n'est pas toujours précisément évalué, or de telles lacunes sont un frein à leur prise en charge. Dans une première partie, les caractéristiques des troubles visuels chroniques ont été mesurées. Il s'agissait de quantifier le pourcentage de plaintes visuelles chroniques chez des patients atteints de sclérose en plaques puis de mesurer le degré d'intensité des troubles visuels chroniques, de déterminer leurs origines physiopathologiques et de rendre compte de leur retentissement sur la qualité de vie des patients se plaignant de troubles chroniques. Les voies visuelles afférentes étaient altérées dans 68% des cas. Des troubles oculomoteurs étaient fréquemment observés (89%) dont le nystagmus pendulaire (28%), source de gêne visuelle. Dans une seconde partie, nous nous sommes donc intéressés au nystagmus pendulaire et à sa conséquence fonctionnelle, l'oscillopsie, afin de proposer une prise en charge spécifique. Néanmoins, les mécanismes de ce nystagmus ne sont pas encore bien définis. Il était donc important de développer une hypothèse explicative à partir de l'observation de deux cas particuliers de nystagmus monoculaire et de démontrer que le nystagmus pendulaire de la sclérose en plaques est à distinguer du nystagmus pendulaire du tremblement oculopalatin, souvent confondus. Enfin, nous proposons une méthode évaluant la détection du mouvement (par stimuli de contraste asservis au regard) ainsi qu'un protocole de stimulation optocinétique tentant de réduire ce symptôme

Perceptual multistability is a phenomenon that is mostly studied in all modalities separately. The phenomenon reveals fundamental principles of the perceptual system in the formation of an emerging cognitive representation in the consciousness. The momentary perceptual organizations evoked during the stimulation with ambiguous stimuli switches between several perceptual organizations or percepts: The auditory streaming stimulus in audition and the moving plaids stimulus in vision, elicit different at least two percepts that dominate awareness exclusively for a random phase or dominance duration before an inevitable switch to another percept occurs. The similarity in the perceptual experience has led to propose a global mechanism contributing to the perceptual multistability phenomena crossmodally. Contrary, the difference in the perceptual experience has led to propose a distributed mechanism that is modality-specific. The development of a hybrid model has synergized both approaches. We accumulate empirical evidence for the contribution of a global mechanism, albeit distributed mechanisms play an indispensable role in this cross-modal interplay. The overt report of the perceptual experience in our experiments is accompanied by the recording of objective, cognitive markers of the consciousness: Reflexive movements of the eyes, namely the dilation of the pupil and the optokinetic nystagmus, correlate with the unobservable perceptual switches and perceptual states respectively and have their neuronal rooting in the brainstem. We complement earlier findings on the sensitivity of the pupil to visual multistability: It was shown in two independent experiments that the pupil dilates at the time of reported perceptual switches in auditory multistability. A control condition on confounding effects from the reporting process confines the results. Endogenous, evoked internally by the unchanged stimulus ambiguity, and exogenous, evoked externally by the changes in the physical properties of the stimulus, perceptual switches could be discriminated based on the maximal amplitude of the dilation. The effect of exogenous perceptual has on the pupil were captured in a report and no-report task to detect confounding perceptual effects. In two additional studies, the moment-by-moment coupling and coupling properties of percepts between concurrent multistable processes in audition, evoked by auditory streaming, and in vision, evoked by moving plaids, were found crossmodally. In the last study, the externally induced percept in the visual multistable process was not relayed to the simultaneous auditory multistable process: Still, the observed general coupling is fragile but existent. The requirement for the investigation of a moment-by-moment coupling of the multistable perceptual processes was the application of a no-report paradigm in vision: The visual stimulus evokes an optokinetic nystagmus that has machine learnable different properties when following either of the two percepts. In combination with the manually reported auditory percept, attentional bottlenecks due to a parallel report were circumvented. The two main findings, the dilation of the pupil along reported auditory perceptual switches and the crossmodal coupling of percepts in bimodal audiovisual multistability, speak in favor of a partly global mechanism being involved in control of perceptual multistability; the global mechanism is incarcerated by the, partly independent, distributed competition of percepts on modality level. Potentially, supramodal attention-related modulations consolidate the outcome of locally distributed perceptual competition in all modalities.:COVER 1 BIBLIOGRAPHISCHE BESCHREIBUNG 2 ACKNOWLEDGEMENTS 3 CONTENTS 4 CHAPTER 1: Introduction 6 C1.1: Stability and uncertainty in perception 6 C1.2: Auditory, visual and audio-visual multistability 14 C1.3: Capturing the subjective perceptual experience 25 C1.4: Limitations of preceding studies, objectives, and outline of the Thesis 33 CHAPTER 2: Study 1 “Pupillometry in auditory multistability” 36 C2.1.1 Experiment 1: Introduction 36 C2.1.2 Experiment 1: Material and Methods 38 C2.1.3 Experiment 1: Data analysis 44 C2.1.4 Experiment 1: Results 48 C2.1.5 Experiment 1: Discussion 52 C2.2.1 Experiment 2: Introduction 54 C2.2.2 Experiment 2: Material and Methods 54 C2.2.3 Experiment 2: Data analysis 56 C2.2.4 Experiment 2: Results 57 C2.3 Experiment 1 & 2: Discussion 61 C2.4 Supplement Study 1 65 CHAPTER 3: Study 2 “Multimodal moment-by-moment coupling in perceptual bistability” 71 C3.1.1 Experiment 1: Introduction 71 C3.1.2 Experiment 1: Results 74 C3.1.3 Experiment 1: Discussion 80 C3.1.4 Experiment 1: Material and Methods 84 C3.1.5 Experiment 1: Data analysis 87 C3.2 Supplement Study 2 92 CHAPTER 4: Study 3 “Boundaries of bimodal coupling in perceptual bistability” 93 C4.1.1 Experiment 1: Introduction 93 C4.1.2 Experiment 1: Material and Methods 98 C4.1.3 Experiment 1: Data analysis 102 C4.1.4 Experiment 1: Results 108 C4.1.5 Experiment 1: Discussion 114 C4.2.1 Experiment 2: Introduction 116 C4.2.2 Experiment 2: Material and Methods 119 C4.2.3 Experiment 2: Data analysis 125 C4.2.4 Experiment 2: Results 133 C4.3 Experiment 1 & 2: Discussion 144 C4.4 Supplement Study 3 151 CHAPTER 5: General Discussion 154 C5.1 Significance for models of multistability and implications for the perceptual architecture 162 C5.2 Recommendations for future research 166 C5.3 Conclusion 168 REFERENCES 170 APPENDIX 186 A1: List of Figures 186 A2: List of Tables 188 A3: List of Abbreviations and Symbols 189

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 Beschreibung 3 Acknowledgments 4 CONTENTS 5 Collaborations 7 List of Figures 8 List of Tables 8 1. Introduction 9 1.1. Tristability 10 1.2. Two or more interpretations? 11 1.3. Multistability in different modalities 12 1.3.1. Auditory multistability 12 1.3.2. Haptic multistability 13 1.3.3. Olfactory multistability 13 1.4. multistability with several interpretations 13 1.5. Measuring multistability 14 1.5.1. The optokinetic nystagmus 14 1.5.2. Pupillometry 15 1.5.3. Measuring auditory multistability 15 1.5.4. Crossmodal multistability 16 1.6. Factors governing multistability 16 1.6.1. Manipulations that do not involve the stimulus 16 1.6.2. Manipulation of the stimulus 17 1.6.2.1. Factors affecting the plaid stimulus 17 1.6.2.2. Factors affecting the auditory streaming stimulus 18 1.7. Goals of this thesis 18 1.7.1. Overview of the thesis 18 2. Parameter dependence in visual pattern-component rivalry at onset and during prolonged viewing 21 2.1. Introduction 21 2.2. Methods 24 2.2.1. Participants 24 2.2.2. Setup 24 2.2.3. Stimuli 25 2.2.4. Procedure 26 2.2.5. Analysis 27 2.2.6. (Generalized) linear mixed-effects models 30 2.3. Results 30 2.3.1. Experiment 1 30 2.3.1.1. Relative number of integrated percepts 31 2.3.1.2. Generalized linear mixed-effects model 32 2.3.1.3. Dominance durations 33 2.3.1.4. Linear mixed-effects models 33 2.3.1.5. Control: Disambiguated trials 33 2.3.1.6. Time course of percept reports at onset 34 2.3.1.7. Eye movements 35 2.3.2. Experiment 2 36 2.3.2.1. Relative number of percepts 36 2.3.2.2. Generalized linear mixed-effects model 37 2.3.2.3. Dominance durations 38 2.3.2.4. Linear mixed-effects model 38 2.3.2.5. Control: Disambiguated trials 40 2.3.2.6. Time course of percept reports at onset 42 2.3.2.7. Eye movements 44 2.4. Discussion 45 2.5. Appendix 49 2.5.1. Appendix A 49 3. Perceptual history 51 3.1. Markov chains 52 3.1.1. Markov chains of order 1 and 2 52 3.2. Testing for Markov chains 55 3.2.1. The method of Naber and colleagues (2010) 56 3.2.1.1. The method 56 3.2.1.2. Advantages and disadvantages of the method 56 3.2.2. Further methods for testing Markov chains 57 3.3. Summary and discussion 58 4. Sequential stopping rules 60 4.1. The COAST rule 61 4.2. The CLAST rule 61 4.3. The variable criteria sequential stopping rule 61 4.4. Discussion 62 4.5. Using the vcSSR when transferring an effect from audition to vision 64 5. Predictability in visual multistability 66 5.1. Pretests 66 5.2. Predictability effects in visual pattern-component rivalry 69 5.2.1. Introduction 69 5.2.2. Methods 71 5.2.2.1. Participants 71 5.2.2.2. Setup 72 5.2.2.3. Stimuli 73 5.2.2.4. Conditions 73 5.2.2.5. Design and procedure 73 5.2.2.6. Analysis 74 5.2.3. Results 75 5.2.3.1. Valid reports 75 5.2.3.2. Verification of reports by eye movements 76 5.2.3.3. Onset latency 76 5.2.3.4. Dominance durations 78 5.2.3.5. Relative dominance of the segregated percept 78 5.2.4. Discussion 78 6. General discussion 83 6.1. Reporting percepts 83 6.1.1. Providing two versus three response options 83 6.1.2. Stimuli with more than three percepts 84 6.1.3. When to pool percepts together and when not 84 6.1.4. Leaving out percepts 87 6.1.5. Measuring (unreported) percepts 88 6.2. Comparing influencing factors on different levels 88 6.3. The use of the vcSSR 90 6.4. Valid reports 90 6.5. Conclusion 93 References 94