A role for backward transitional probabilities in word segmentation?

A number of studies have shown that people exploit transitional probabilities between successive syllables to segment a stream of artificial continuous speech into words. It is often assumed that what is actually exploited are the forward transitional probabilities (given XY, the probability that X will be followed by Y), even though the backward transitional probabilities (the probability that Y has been preceded by X) were equally informative about word structure in the languages involved in those studies. In two experiments, we showed that participants were able to learn the words from an artificial speech stream when the only available cues were the backward transitional probabilities. Learning is as good under those conditions as when the only available cues are the forward transitional probabilities. Implications for some current models of word segmentation, particularly the simple recurrent networks and PARSER models, are discussed.     

Development of children's mental representations: effects of age, sex, and school experience

In the present study mental representations in drawings by 158 young children, ages 2 1/2 to 6 yr. old were analysed. The aim was to investigate whether the accuracy of mental representations increased with age and how this development progressed. Also tested were whether the inferred mental representations differed for boys and girls and whether preschool experience affected the drawings. As expected, mental representation increased in complexity with age as measured by Goodenough's score, and girls' mental representations (drawings) were significantly more elaborate than boys. Moreover, attending school early seemed to affect mental representations of the 3-yr.-olds but not the 4-yr.-olds. Results are discussed in terms of internal and external factors in mental representation in drawing a man.     

Perceptual processing of partially and fully assimilated words in French

Models of speech perception attribute a different role to contextual information in the processing of assimilated speech. This study concerned perceptual processing of regressive voice assimilation in French. This phonological variation is asymmetric in that assimilation is partial for voiced stops and nearly complete for voiceless stops. Two auditory-visual cross-modal form priming experiments were used to examine perceptual compensation for assimilation in French words with voiceless versus voiced stop offsets. The results show that, for the former segments, assimilating context enhances underlying form recovery, whereas it does not for the latter. These results suggest that two sources of information -- contextual information and bottom-up information from the assimilated forms themselves -- are complementary and both come into play during the processing of fully or partially assimilated word forms.     

The scope and limits of enactive approaches to visual experience

I pursue here three related aims. First, I criticise some of the metaphysical claims made on behalf of the so-called 'enactive' approach to visual experience. Secondly, I explain why the enactive view of visual experience is hard to square with the evidence in favour of the two-visual-systems model of human vision. Finally, I explore one possible way to develop the 'pre-emptive perception' framework and explain why, contrary to first appearances, some of the fundamental discoveries of brain mechanisms, whose function might be to underlie pre-emptive perception, do not really support the enactive approach to visual experience.     

Shades of disengagement: high school dropouts speak out

The purpose of this study was to describe how dropouts navigate their educational journeys. Eighty dropouts participated to individual interviews which were recorded and transcribed. The data analysis yielded three broad categories in answering the research question. Setting the stage in the family and the school, the dropouts described their teetering between in and out of school contexts and proceeded to explain how they ended their educational journey. For 20 dropouts, family turmoil represented a pervasive force negatively influencing their schooling. For 24 dropouts, problems in school set the stage for dropping out. Teetering represented juggling strategies to prolongand to sabotage the journey, while the end of the journey occurred as a result of a pivotal moment (48%) or a gradual fade out (52%) from the school context.

Perceived behavioral changes in early multiple sclerosis

Acquired behavioral changes have essentially been described in advanced multiple sclerosis (MS). The present study was designed to determine whether behavioral modifications specifically related to the MS pathological process could be identified in the initial phase of the disease, as compared to control patients with chronic, relapsing and progressive inflammatory disorders not involving the central nervous system (CNS). Eighty-eight early MS patients (Expanded Disability Status Scale score 相似文献   

Clinical assessment of motor function: a processes oriented instrument based on a speed-accuracy trade-off paradigm

In this study, we developed a digitizing tablet-based instrument for the clinical assessment of human voluntary movements targeting motor processes of planning, programming and execution. The tool was used to investigate an adaptation of Fitts' reciprocal tapping task [10], comprising four conditions, each of them modulated by three indices of difficulty related to the amplitude of movement required. Temporal, spatial and sequential constraints underlying the various conditions allowed the intricate motor processes to be dissociated. Data obtained from a group of elderly healthy subjects (N=50) were in agreement with the literature on motor control, in the temporal and spatial domains. Speed constraints generated gains in the temporal domain and costs in the spatial one, while spatial constraints generated gain in the spatial domain and costs in the temporal one; finally, sequential constraints revealed the integrative nature of the cognitive operations involved in motor production. This versatile instrument proved capable of providing quantitative, accurate and sensitive measures of the various processes sustaining voluntary movement in healthy subjects. Altogether, analyses performed in this study generated a theoretical framework and reference data which could be used in the future for the clinical assessment of patients with various movement disorders, in particular Parkinson's disease.