Perceptual integration of indexical information in bilingual speech

The present research examines how different types of indexical information, namely talker information and the language being spoken, are perceptually integrated in bilingual speech. Using a speeded classification paradigm (Garner, 1974), variability in characteristics of the talker (gender in Experiment 1 and specific talker in Experiment 2) and in the language being spoken (Mandarin vs. English) was manipulated. Listeners from two different language backgrounds, English monolinguals and Mandarin-English bilinguals, were asked to classify short, meaningful sentences obtained from different Mandarin-English bilingual talkers on these indexical dimensions. Results for the gender-language classification (Exp. 1) showed a significant, symmetrical interference effect for both listener groups, indicating that gender information and language are processed in an integral manner. For talker-language classification (Exp. 2), language interfered more with talker than vice versa for the English monolinguals, but symmetrical interference was found for the Mandarin-English bilinguals. These results suggest both that talker-specificity is not fully segregated from language-specificity, and that bilinguals exhibit more balanced classification along various indexical dimensions of speech. Currently, follow-up studies investigate this talker-language dependency for bilingual listeners who do not speak Mandarin in order to disentangle the role of bilingualism versus language familiarity

Illusory streaks from corners and their perceptual integration

Perceptual grouping appears both as organized forms of real figural units and as illusory or “phantom” figures. The phenomenon is visible in the Hermann grid and in configurations which generate color spreading, e.g., “neon effects.” These configurations, generally regular repetitive patterns, appear to be crossed by illusory bands filled with a brighter shade or a colored tinge connecting the various loci of illusory effects. In this work, we explore a particular new illusion showing a grouping effect. It manifests as illusory streaks irradiating from the vertexes of angular contours and connecting pairs of figures nearby. It is only clearly visible when more than one figure is shown, and takes the shape of a net crossing their corners. Although the grouping effect is vivid, the local source of the illusion is completely hidden. Theories explaining this effect as due to the irradiation of illusory streaks (mainly that of Grossberg and Mingolla, 1985a,b) do not fully explain the figural patterns presented here. Illusory effects have already been documented at the angles of various figures, causing them to alter in amplitude and brightness; however, the figure illustrated here appears to have different features and location. Phenomenological observations and an experiment were conducted to assess the role played by geometric and photometric parameters in this illusion. Results showed that sharp angles, in low contrast with the surround, are the main source of the illusion which, however, only becomes visible when at least two figures are close together. These findings are discussed with respect to theories of contour processing and perceptual grouping, and in relation to other illusions

Visualisation techniques, human perception and the built environment

Historically, architecture has a wealth of visualisation techniques that have evolved throughout the period of structural design, with Virtual Reality (VR) being a relatively recent addition to the toolbox. To date the effectiveness of VR has been demonstrated from conceptualisation through to final stages and maintenance, however, its full potential has yet to be realised (Bouchlaghem et al, 2005). According to Dewey (1934), perceptual integration was predicted to be transformational; as the observer would be able to ‘engage’ with the virtual environment. However, environmental representations are predominately focused on the area of vision, regardless of evidence stating that the experience is multi sensory. In addition, there is a marked lack of research exploring the complex interaction of environmental design and the user, such as the role of attention or conceptual interpretation. This paper identifies the potential of VR models to aid communication for the Built Environment with specific reference to human perception issues

The Effects of Category Overlap on Information-Integration and Rule-Based Category Learning

Three experiments investigate whether the amount of category overlap constrains the decision strategies used in category learning, and whether such constraints depend on the type of category structures used. Experiments 1 and 2 used a category learning task requiring perceptual integration of information from multiple dimensions (information-integration task) and Experiment 3 used a task requiring the application of an explicit strategy (rule-based task). In the information-integration task, participants used perceptual-integration strategies at moderate levels of category overlap, but explicit strategies at extreme levels of overlap – even when such strategies were sub-optimal. In contrast, in the rule-based task, participants used explicit strategies regardless of the level of category overlap. These data are consistent with a multiple systems view of category learning, and suggest that categorization strategy depends on the type of task that is used, and on the degree to which each stimulus is probabilistically associated with the contrasting categories

Why early tactile speech aids may have failed: no perceptual integration of tactile and auditory signals

Tactile speech aids, though extensively studied in the 1980s and 90s, never became a commercial success. A hypothesis to explain this failure might be that it is difficult to obtain true perceptual integration of a tactile signal with information from auditory speech: exploitation of tactile cues from a tactile aid might require cognitive effort and so prevent speech understanding at the high rates typical of everyday speech. To test this hypothesis, we attempted to create true perceptual integration of tactile with auditory information in what might be considered the simplest situation encountered by a hearing-impaired listener. We created an auditory continuum between the syllables BA and VA, and trained participants to associate BA to one tactile stimulus VA to another tactile stimulus. After training, we tested if auditory discrimination along the continuum between the two syllables could be biased by incongruent tactile stimulation. We found that such a bias occurred only when the tactile stimulus was above its previously measured tactile discrimination threshold. Such a pattern is compatible with the idea that the effect is due to a cognitive or decisional strategy, rather than to truly perceptual integration. We therefore ran a further study, where we created a tactile version of the McGurk effect. We extensively trained two Subjects over six days to associate four recorded auditory syllables with four corresponding apparent motion tactile patterns. In a subsequent test, we presented stimulation that was either congruent or incongruent with the learnt association, and asked Subjects to report the syllable they perceived. We found no analog to the McGurk effect. These findings strengthen our hypothesis according to which tactile aids failed because integration of tactile cues with auditory speech occurred at a cognitive or decisional level, rather than truly at a perceptual leve

Perceptual integration of odor mixtures

Virtually all perceptions of environmental odors are based on an integration process of many volatile components, in many cases hundreds of components. By investigating the perceptual dimensions in this perceptual integration process and how it is affected by the neurophysiology of the olfactory system we can begin to understand the nature of complex odor perception. The aim of this thesis is to describe and model the perceptual integration process by investigating how two single components integrate into an odor percept. Study I showed that the odor of an agonist, as hypothesized, was dominated by the odor of an antagonist. Study II implicated that peripheral processing plays an important role in integrating odorants into the mixture perception, with higher intensities and more stable perception of quality when bypassing this level of interaction. Electrophysiological measurements converged with these perceptual effects. Study III showed that the pleasantness of single odorants is dependent on intensity as described by a certain family of 2nd degree polynomials. The pleasantness of mixtures is dependent on the quality change and the shift in intensity that occurs when one odorant is added to another. The pleasantness of mixtures can be predicted along a quality-weighted average of the individual functions. Study IV showed that mixture quality is not tied to any particular single component, which indicates that we perceive odor mixture more or less synthetically as a unitary percept. In addition, the study showed that the perceived quality and pleasantness of combined odorants is a simple function of the component qualities such that mixture quality is intermediate to its components’ quality in perceptual space. The combined results from these studies suggest that integration of odors into a mixture percept is dependent on the interaction at the peripheral level of the olfactory system, the receptor epithelia. In addition, the quality of an odor mixture tends to be intermediate to those of its components in a perceptual space and the odor mixture percept tends to be synthesized into a unitary homogeneous percept. Finally, a psychophysical model of mixture integration describing the interplay between fundamental dimensions of the odor percept: intensity, quality, and pleasantness is developed and tested

Perceptual Integration of Acoustic Cues to Laryngeal Contrasts in Korean Fricatives

This paper provides evidence that multiple acoustic cues involving the presence of lowfrequency energy integrate in the perception of Korean coronal fricatives. This finding helps explain a surprising asymmetry between the production and perception of these fricatives found in previous studies: lower F0 onset in the following vowel leads to a response bias for plain [s] over fortis [s*], despite the fact that there is no evidence for a corresponding acoustic asymmetry in the production of [s] and [s*]. A fixed classification task using the Garner paradigm provides evidence that low F0 in a following vowel and the presence of voicing during frication perceptually integrate. This suggests that Korean listeners in previous experiments were responding to an “intermediate perceptual property” of stimuli, despite the fact that the individual acoustic components of that property are not all present in typical Korean fricative productions. The finding also broadens empirical support for the general idea of perceptual integration to a language, a different manner of consonant, and a situation where covariance of the acoustic cues under investigation is not generally present in a listener’s linguistic input