Rapid recalibration of speech perception after experiencing the McGurk illusion

The human brain can quickly adapt to changes in the environment. One example is phonetic recalibration: a speech sound is interpreted differently depending on the visual speech and this interpretation persists in the absence of visual information. Here, we examined the mechanisms of phonetic recalibration. Participants categorized the auditory syllables /aba/ and /ada/, which were sometimes preceded by the so-called McGurk stimuli (in which an /aba/ sound, due to visual /aga/ input, is often perceived as 'ada'). We found that only one trial of exposure to the McGurk illusion was sufficient to induce a recalibration effect, i.e. an auditory /aba/ stimulus was subsequently more often perceived as 'ada'. Furthermore, phonetic recalibration took place only when auditory and visual inputs were integrated to 'ada' (McGurk illusion). Moreover, this recalibration depended on the sensory similarity between the preceding and current auditory stimulus. Finally, signal detection theoretical analysis showed that McGurk-induced phonetic recalibration resulted in both a criterion shift towards /ada/ and a reduced sensitivity to distinguish between /aba/ and /ada/ sounds. The current study shows that phonetic recalibration is dependent on the perceptual integration of audiovisual information and leads to a perceptual shift in phoneme categorization

Circumstellar Dust Shells of Pulsating Red Giants as Dynamical Systems

Miras and long-period variables (LPVs) are highly evolved, pulsating stars on the Asymptotic Giant Branch (AGB) with massive outflows and prominent circumstellar dust shells (CDSs). A CDS, driven by the stellar pulsation, can be considered as a dynamical system which reveals various kinds of complex phenomena like spatio-temporal instabilities, bifurcations, multiperiodicity and transition to chaos. In order to analyze the temporal behavior of the CDS standard methods known from the theory of non-linear dynamical systems are applied. We have developed a spherical symmetric, multi-zone description for the CDS which includes the important physical interactions by means of non-linear coupling terms. The corresponding Hamiltonians are derived. We present Poincaré maps for several models with a different number of zones in order to characterize their dynamical stability. The role of pulsation and dust formation for the development of the dynamical structure of the CDS is investigated. In addition, the linearized approximation of an one-zone model is discussed with respect to the Kolmogorov-Arnold-Moser and the Poincaré-Birkhoff theorems

Supplemental Information: Rapid recalibration of speech perception after experiencing the McGurk illusion

Supplemental results, figure, tabl

Supplemental Information: Rapid recalibration of speech perception after experiencing the McGurk illusion

Supplemental results, figure, tabl