An alternative account of the locus equation phenomenon based on recent theories of speech movement planning is provided. It is similar to Sussman et al.'s account in positing that our productions are tuned to satisfy auditory constraints. It differs by suggesting that the locus equation effect may be an epiphenomenon of a planning process that satisfies simpler auditory constraints.

BackgroundReflexive pitch perturbation experiments are commonly used to investigate the neural mechanisms underlying vocal motor control. In these experiments, the fundamental frequency–the acoustic correlate of pitch–of a speech signal is shifted unexpectedly and played back to the speaker via headphones in near real-time. In response to the shift, speakers increase or decrease their fundamental frequency in the direction opposing the shift so that their perceived pitch is closer to what they intended. The goal of the current work is to develop (...) a quantitative model of responses to reflexive perturbations that can be interpreted in terms of the physiological mechanisms underlying the response and that captures both group-mean data and individual subject responses.MethodsA model framework was established that allowed the specification of several models based on Proportional-Integral-Derivative and State-Space/Directions Into Velocities of Articulators (DIVA) model classes. The performance of 19 models was compared in fitting experimental data from two published studies. The models were evaluated in terms of their ability to capture both population-level responses and individual differences in sensorimotor control processes.ResultsA three-parameter DIVA model performed best when fitting group-mean data from both studies; this model is equivalent to a single-rate state-space model and a first-order low pass filter model. The same model also provided stable estimates of parameters across samples from individual subject data and performed among the best models to differentiate between subjects. The three parameters correspond to gains in the auditory feedback controller’s response to a perceived error, the delay of this response, and the gain of the somatosensory feedback controller’s “resistance” to this correction. Excellent fits were also obtained from a four-parameter model with an additional auditory velocity error term; this model was better able to capture multi-component reflexive responses seen in some individual subjects.ConclusionOur results demonstrate the stereotyped nature of an individual’s responses to pitch perturbations. Further, we identified a model that captures population responses to pitch perturbations and characterizes individual differences in a stable manner with parameters that relate to underlying motor control capabilities. Future work will evaluate the model in characterizing responses from individuals with communication disorders. (shrink)

This commentary focuses on the importance of auditory object processing for producing and comprehending human language, the relative lack of development of this capability in nonhuman primates, and the consequent need for hominid neurobiological evolution to enhance this capability in making the transition from protosign to protospeech to language.

Role of the entrepreneur in a distinct role of profit.

Corporate social policy can be viewed as three legs of a tripod: efficient production, stable employment, and a social and political environment that promotes high performance of both workers and managers.Social policy process consists of achieving a balance of corporate interest with other interests in the society. Each policy position taken by the firm alters its relationships with all other interests and creates a new balance. This entails the risk of creating unfriendly interests and losing the support of others, depending (...) on the issue and shift in power. (shrink)

The mid-1880s, like the mid-1870s, were a time of considerable turmoil for American workers. Unemployment and wage cuts were widespread and workers responded with strikes, boycotts, union organizing, local labor tickets, and a bewildering variety of reform schemes and ideologies. Perhaps the central event of the 1880s was the Haymarket incident. The bomb and subsequent trial had a broad historical impact, sparking a red scare, blunting the eight-hour movement, establishing the stereotype of anarchists as wildeyed, foreign bombthrowers, and intensifying calls (...) for immigration restriction. (shrink)

The temporal granularity of consciousness may be far less fine than the real-time information processing mechanisms that underlie our sensitivity to small temporal differences. It is suggested that conscious time perception, like space perception, is subject to errors that belie a unitary underlying representation. E. R. Clay's concept of the “specious present,” an extended moment represented in consciousness, is suggested as an alternative to the more common notion of instantaneous experience that underlies much reasoning based on the “time of arrival” (...) in consciousness. (shrink)

The major tenets of the recent hypothesis of punctuated equilibrium are explicit in Darwin's writing. His notes from 1837–1838 contain references to stasis and rapid change. In the first edition of the Origin (1859), Darwin described the importance of isolation of local varieties in the process of speciation. His views on the tempo of speciation were influenced by Hugh Falconer and also, perhaps, by Edward Suess (1831–1914). It is paradoxical that, although both topics were recorded in his unpublished notes of (...) 1837–1838, the second was not explicitly and fully discussed until the fourth edition of the Origin (1866). While no wholly satisfactory explanation of this paradox suggests itself, it seems probable that Falconer's work on the persistence of fossil species of elephant helped Darwin to see the wider significance of the tempo of evolution for his general theory. (shrink)

Increasing complexities facing physicians negotiating the bedside decision continue to fuel the debate over who is the appropriate party to offer ethics consults, should one be needed, during the decision-making process. Some very good arguments have been put forth on behalf of clinical ethicists as being the proper and best party to engage in ethics consultations. However, serious questions remain about the role of the clinical ethicist and his ability to provide the necessary level of objectivity called for in an (...) ethics consult.I argue that the clinician's professional psyche, or mode of thinking as a professional, leaves him little room to maneuver as an objective and detached third party ethics consultant. Several factors are cited and discussed that greatly influence the analyses applied to a case problem by physicians. The most formidable of these factors are habits and the practice of defensive medicine. I conclude that clinical ethicists are less suited for the overall tasks required of an objective consultant in medical cases that appear to involve insurmountable ethical issues. (shrink)

A new motion illusion is discussed in relation to the idea of vision as a Grand Illusion. An experiment shows that this 'Tinkerbell effect' is a good example of a visual illusion supported by low-level stimulus information, but resulting from integration principles probably necessary for normal perception.

There are problems with both the theoretical logic and the interpretation of data in Christie and Barresi's interesting article. The general pattern of results is easily incorporated into an information-processing framework compatible with Dennett's analysis. In particular, different aspects of the illusory motion event are queried at different times and these aspects are not in conflict, so no revision of conscious content is necessary. Second, too much interpretive weight is placed on an anomalous pair of data points that do not (...) seem fully interpretable within the author's framework and are probably susceptible to one of several alternative interpretations proposed here, though further investigation is necessary. (shrink)

Although Pessoa et al. imply that many aspects of the filling-in debate may be displaced by a regard for active vision, they remain loyal to naive neural reductionist explanations of certain pieces of psychophysical evidence. Alternative interpretations are provided for two specific examples and a new category of filling-in (of visual detail) is proposed.

Medicine and Money explores the role of beneficence and cost control in health-care systems. The book's primary concern of morally improving medicine is achieved by dividing the argument into two parts. The first defines the crisis in health-care and justifies beneficence. The second part offers practical suggestions on implementing beneficence into the system. Medicine and Money is one of the few books to provide concrete suggestions on improving the health-care system from the micro level for addressing cost concerns in a (...) morally acceptable manner. (shrink)

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From Heidegger's letters to Elisabeth Blochmann in 1932, it is apparent that he is on the verge of crossing the Rubicon into the political arena. On December 19, 1932, Heidegger tells her.