1,720,986 research outputs found
Automatic audiovisual integration in speech perception.
No full textTwo experiments aimed to determine whether features of both the visual and acoustical inputs are always merged into the perceived representation of speech and whether this audiovisual integration is based on either cross-modal binding functions or on imitation. In a McGurk paradigm, observers were required to repeat aloud a string of phonemes uttered by an actor (acoustical presentation of phonemic string) whose mouth, in contrast, mimicked pronunciation of a different string (visual presentation). In a control experiment participants read the same printed strings of letters. This condition aimed to analyze the pattern of voice and the lip kinematics controlling for imitation. In the control experiment and in the congruent audiovisual presentation, i.e. when the articulation mouth gestures were congruent with the emission of the string of phones, the voice spectrum and the lip kinematics varied according to the pronounced strings of phonemes. In the McGurk paradigm the participants were unaware of the incongruence between visual and acoustical stimuli. The acoustical analysis of the participants' spoken responses showed three distinct patterns: the fusion of the two stimuli (the McGurk effect), repetition of the acoustically presented string of phonemes, and, less frequently, of the string of phonemes corresponding to the mouth gestures mimicked by the actor. However, the analysis of the latter two responses showed that the formant 2 of the participants' voice spectra always differed from the value recorded in the congruent audiovisual presentation. It approached the value of the formant 2 of the string of phonemes presented in the other modality, which was apparently ignored. The lip kinematics of the participants repeating the string of phonemes acoustically presented were influenced by the observation of the lip movements mimicked by the actor, but only when pronouncing a labial consonant. The data are discussed in favor of the hypothesis that features of both the visual and acoustical inputs always contribute to the representation of a string of phonemes and that cross-modal integration occurs by extracting mouth articulation features peculiar for the pronunciation of that string of phoneme
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Impaired control of an action after supplementary motor area lesion: A case study
No full textThe kinematics of the action formed by reaching±grasping an object and placing it on a second target was studied in a patient
who su ered from an acute vascular left brain lesion, which a ected the Supplementary Motor Area proper (SMA-proper)
(Matelli M, Luppino G. Thalamic input to mesial and superior area 6 in the macaque monkey. Journal of Comparative
Neurology 1996;372:59±87, Matelli M, Luppino G, Fogassi L, Rizzolatti G. Thalamic input to inferior area 6 and area 4 in the
macaque monkey. Journal of Comparative Neurology 1989;280:468±488), and in ®ve healthy control subjects. The reach kinematics of the controls was a ected by the positions of both the reaching±grasping and the placing targets (Gentilucci M,
Negrotti A, Gangitano M. Planning an action. Experimental Brain Research 1997;115:116±28). In contrast, the reach kinematics
of the patient was a ected only by the position of the reaching±grasping target. By comparing these results with those
previously found in Parkinson's disease patients executing the same action (Gentilucci M, Negrotti A. Planning and executing an
action in Parkinson's disease patients. Movement Disorders 1999;1:69±79, Gentilucci M, Negrotti A. The control of an action in
Parkinson's disease. Experimental Brain Research 1999;129:269±277), we suggest that the anatomical ``motor'' circuit formed by SMA-proper (see above), Basal Ganglia (BG) and Thalamus (Alexander GE, Crutcher MD. Functional architecture of basal ganglia circuits: neural substrates of parallel processing. Trends in the Neurosciences 1990;13:266±271, Hoover JE, Strick PL.
Multiple output channels in the basal ganglia. Nature 1993;259:819±821) may be involved in the control of actions: SMA-proper assembles the sequence of the action, whereas BG updates its parameters and stores them
Recognising a hand by grasp
No full textThe present study aimed to demonstrate that motor representations are used to recognise biological stimuli. In three experiments subjects were required to judge laterality of hands and forearms presented by pictures. The postures of the hands were those assumed when holding a small, medium and large sphere. In experiment 1, the sphere held in hand was presented, whereas in experiment 2 it was absent. In experiment 3, the same images, showing holding-a-sphere hands, as in experiment 1 were presented, but without forearm. In all experiments one finger of each hand could be absent. In experiment 1 recognition time was longer for those hand postures for which the corresponding grasping motor acts required more accuracy. This was confirmed by a control experiment (experiment 4), in which subjects actually grasped the spheres. Absence of fingers did not influence right–left hand recognition. However, the absence of target object in experiment 2, and of forearm in experiment 3 reduced the effects of the type of holding on hand laterality recognition. The results of the present study indicate that grasp representations are used to recognise hand laterality. In particular, the visual description of how hand and object interact in space (the opposition space [M.A. Arbib, Programs, schemas and neural networks for control of hand movement: beyond the RS frameworks, in: M. Jeannerod (Ed.), Attention and Performance XIII: Motor Representation and Control, Lawrence Erlbaum, Hillsdale, NJ, 1990, 111–138; M.A. Arbib, T. Iberall, D. Lyons, Coordinated control programs for movements of the hand, in: A.W. Goodman, I. Darian-Smith (Eds.), Hand function and the neocortex, Springer, Berlin, 1985, pp. 135–170]) and the anchoring of the hand to the agent are the features of the grasp representations used in hand-recognition processes. The data are discussed according to the more general notion that motor representations are automatically extracted in the process of intuiting situations, or people's intentions. These motor representations, which are compared with those of other people, contain concrete information on the actions (the motor program) by which a situation is created and on the aim of the agents executing those actions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
On the tip of the tongue: modulation of the primary motor cortex during audiovisual speech perception
No full textRecent neurophysiological studies show that cortical brain regions involved in the planning and execution of speech gestures are also activated in processing speech sounds. These findings suggest that speech perception is in part mediated by reference to the motor actions afforded in the speech signal. Since interactions between auditory and visual modalities are beneficial in speech perception and face-to-face communication, we used single-pulse transcranial magnetic stimulation (TMS) to investigate whether audiovisual speech perception might induce excitability changes in the left tongue-related primary motor cortex and whether acoustic and visual speech inputs might differentially modulate motor excitability. To this aim, motor-evoked potentials obtained with focal TMS applied over the left tongue primary motor cortex were recorded from participants’ tongue muscles during the perception of matching and conflicting audiovisual syllables incorporating tongue- and/or lip-related phonemes (i.e. visual and acoustic /ba/, /ga/ and /da/, visual /ba/ and acoustic /ga/, visual /ga/ and acoustic /ba/). Compared to the presentation of congruent /ba/ syllable, which primarily involves lip movements when pronounced, exposure to syllables incorporating visual and/or acoustic tongue-related phonemes induced a greater excitability of the left tongue primary motor cortex as early as 100–200 ms after the consonantal onset of the acoustically presented syllable. These results provide evidence that both visual and auditory modalities specifically modulate activity in the tongue primary motor cortex at an early stage during audiovisual speech perception. Because no interaction between the two modalities was observed, these results suggest that information from each sensory channel is recoded separately in the primary motor cortex at that point of time. These findings are discussed in relation to theories assuming a link between perception and action in the human speech processing system and theoretical models of audiovisual interaction
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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