Signal dimensionality and the emergence of combinatorial structure

© 2017 Elsevier B.V. In language, a small number of meaningless building blocks can be combined into an unlimited set of meaningful utterances. This is known as combinatorial structure. One hypothesis for the initial emergence of combinatorial structure in language is that recombining elements of signals solves the problem of overcrowding in a signal space. Another hypothesis is that iconicity may impede the emergence of combinatorial structure. However, how these two hypotheses relate to each other is not often discussed. In this paper, we explore how signal space dimensionality relates to both overcrowding in the signal space and iconicity. We use an artificial signalling experiment to test whether a signal space and a meaning space having similar topologies will generate an iconic system and whether, when the topologies differ, the emergence of combinatorially structured signals is facilitated. In our experiments, signals are created from participants’ hand movements, which are measured using an infrared sensor. We found that participants take advantage of iconic signal-meaning mappings where possible. Further, we use trajectory predictability, measures of variance, and Hidden Markov Models to measure the use of structure within the signals produced and found that when topologies do not match, then there is more evidence of combinatorial structure. The results from these experiments are interpreted in the context of the differences between the emergence of combinatorial structure in different linguistic modalities (speech and sign)

Evolutionary Dynamics Do Not Motivate a Single-Mutant Theory of Human Language

One of the most controversial hypotheses in cognitive science is the Chomskyan evolutionary conjecture that language arose instantaneously in humans through a single mutation. Here we analyze the evolutionary dynamics implied by this hypothesis, which has never been formalized before. The hypothesis supposes the emergence and fixation of a single mutant (capable of the syntactic operation Merge) during a narrow historical window as a result of frequency-independent selection under a huge fitness advantage in a population of an effective size no larger than ~15 000 individuals. We examine this proposal by combining diffusion analysis and extreme value theory to derive a probabilistic formulation of its dynamics. We find that although a macro-mutation is much more likely to go to fixation if it occurs, it is much more unlikely a priori than multiple mutations with smaller fitness effects. The most likely scenario is therefore one where a medium number of mutations with medium fitness effects accumulate. This precise analysis of the probability of mutations occurring and going to fixation has not been done previously in the context of the evolution of language. Our results cast doubt on any suggestion that evolutionary reasoning provides an independent rationale for a single-mutant theory of language

Acoustic models of orangutan hand-assisted alarm calls

B.d.B. was funded by the European research council starting grant ABACUS project and the Innoviris ‘Brains back to Brussels’ programme. S.A.W. was funded by the Netherlands Organisation for Scientific Research NWO. A.R.L. was funded by the Menken Funds (University of Amsterdam).Orangutans produce alarm calls called kiss-squeaks, which they sometimes modify by putting a hand in front of their mouth. Through theoretical models and observational evidence, we show that using the hand when making a kiss-squeak alters the acoustics of the production in such a way that more formants per kilohertz are produced. Our theoretical models suggest that cylindrical wave propagation is created with the use of the hand and face as they act as a cylindrical extension of the lips. The use of cylindrical wave propagation in animal calls appears to be extremely rare, but is an effective way to lengthen the acoustic system; it causes the number of resonances per kilohertz to increase. This increase is associated with larger animals, and thus using the hand in kiss-squeak production may be effective in exaggerating the size of the producer. Using the hand appears to be a culturally learned behavior, and therefore orangutans may be able to associate the acoustic effect of using the hand with potentially more effective deterrence of predators.Publisher PDFPeer reviewe

The accuracy and timing of pedestrian warnings at intersections: the acceptance from drivers and their preferences

The safety of vulnerable road users at traffic intersections is critical. Driver assistance systems can improve safety but have to rely on accurate detection of hazardous situations. Given the complexity of pedestrian movement, detection of pedestrian presence and prediction of their behaviour are not always without error. Drivers' attitude towards such errors is an important issue for the effectiveness of the system. An online questionnaire survey has been carried out to investigate drivers' acceptance of the system under different reliability and accuracy configurations. The results show that safety warnings of pedestrians are generally found to be useful, although false positives and false negatives tend to reduce its pleasantness. The system is found to be most useful for right turn movement at a busy intersection, compared to through movements and quiet intersections. Drivers also find false alarms more acceptable than false negatives. In terms of timing of the warning message, drivers prefer to receive it earlier rather than later

Sustainability in Growth Models

We study the relation between sustainability and national income in a neoclassical growth model with one product, which is used both as consumption good and investment good, and one natural resource, which is used in production. We analyse the possibilities for an indicator of sustainability, looking in particular at two indicators: the change in real national wealth and the ratio between sustainable constant consumption and actual consumption. It appears that both indicators can only be computed if the sustainable path of the economy is first computed, ànd that they must be computed for the whole future path of the economy, so that it is not sufficient to compute them for a single time period. For official statistics this means that sustainability indicators can only be computed by means of an economic model, and cannot be measured with actual data only

Sustainability in Growth Models

We study the relation between sustainability and national income in a neoclassical growth model with one product, which is used both as consumption good and investment good, and one natural resource, which is used in production. We analyse the possibilities for an indicator of sustainability, looking in particular at two indicators: the change in real national wealth and the ratio between sustainable constant consumption and actual consumption. It appears that both indicators can only be computed if the sustainable path of the economy is first computed, ànd that they must be computed for the whole future path of the economy, so that it is not sufficient to compute them for a single time period. For official statistics this means that sustainability indicators can only be computed by means of an economic model, and cannot be measured with actual data only

Language: Meaning and Form. 2. Grammaticalization and Lexicalization in the System of Latvian

Krājums „Valoda: nozīme un forma. 2. Gramatizēšanās un leksikalizēšanās latviešu valodas sistēmā” iecerēts kā 2010. un 2011. gada semināros „Gramatizēšanās un leksikalizēšanās latviešu valodas sistēmā” nolasīto referātu apkopojums

Comparative in vitro evaluation of four corticosteroid metered dose inhalers:Consistency of delivered dose and particle size distribution

SummaryIntroductionRecent developments concerning pressurized metered dose inhalers (pMDIs) with inhaled corticosteroids (ICS) are the introduction of ciclesonide and the replacement of propellants. As the results of in vivo studies depend on pMDIperformance, it is necessary to evaluate pMDIs in vitro for delivered dose and particle size distributions under different conditions.MethodsFluticasone 125μg, budesonide 200μg, beclomethasone HFA100μg, and ciclesonide 160μg were compared for delivered dose and particle size using laser diffraction analysis with inspiratory flow rates of 10, 20 and 30l/s.ResultsThe volume median diameter of budesonide was 3.5μm, fluticasone 2.8μm, beclomethasone and ciclesonide both 1.9μm. The mouthpiece retention was up to 30% of the nominal dose for beclomethasone and ciclesonide, 11–19% for the other pMDIs. Lifespan, flow rate, and air humidity had no significant influence on particle size distribution. The delivered dose of beclomethasone, budesonide, and ciclesonide remained constant over the lifespan. The delivered dose of fluticasone 125 decreased from 106% to 63%; fluticasone 250 also decreased whereas fluticasone 50 remained constant.ConclusionsThere is a significant difference in median particle size distribution between the different ICS pMDIs. Air humidity and inspiratory flow rate have no significant influence on particle size distribution. Ciclesonide 160 and beclomethasone 100 deliver the largest fine particle fractions of 1.1–3.1μm. The changes in delivered dose during the lifespan for the fluticasone 125 and 250 may have implications for patient care