Deriving auditory features from triadic comparisons

A feature-based representation of auditory stimuli is proposed and tested experimentally. Within a measurement-theoretical framework, it is possible to decide whether a representation of subjective judgments with a set of auditory features is possible and how unique such a representation is. Furthermore, the method avoids confounding listeners' perceptual and verbal abilities, in that it strictly separates the process of identifying auditory features from labeling them. The approach was applied to simple synthetic sounds with well-defined physical properties (narrow-band noises and complex tones). For each stimulus triad, listeners had to judge whether the first two sounds displayed a common feature that was not shared by the third, by responding with a simple "yes" or "no." Because of the high degree of consistency in the responses, feature structures could be obtained for most of the subjects. In summary, the proposed procedure constitutes a supplement to the arsenal of psychometric methods with the main focus of identifying the type of sensation itself, rather than of measuring its threshold or magnitude.     

Exploiting redundancy for flexible behavior: unsupervised learning in a modular sensorimotor control architecture

Autonomously developing organisms face several challenges when learning reaching movements. First, motor control is learned unsupervised or self-supervised. Second, knowledge of sensorimotor contingencies is acquired in contexts in which action consequences unfold in time. Third, motor redundancies must be resolved. To solve all 3 of these problems, the authors propose a sensorimotor, unsupervised, redundancy-resolving control architecture (SURE_REACH), based on the ideomotor principle. Given a 3-degrees-of-freedom arm in a 2-dimensional environment, SURE_REACH encodes 2 spatial arm representations with neural population codes: a hand end-point coordinate space and an angular arm posture space. A posture memory solves the inverse kinematics problem by associating hand end-point neurons with neurons in posture space. An inverse sensorimotor model associates posture neurons with each other action-dependently. Together, population encoding, redundant posture memory, and the inverse sensorimotor model enable SURE_REACH to learn and represent sensorimotor grounded distance measures and to use dynamic programming to reach goals efficiently. The architecture not only solves the redundancy problem but also increases goal reaching flexibility, accounting for additional task constraints or realizing obstacle avoidance. While the spatial population codes resemble neurophysiological structures, the simulations confirm the flexibility and plausibility of the model by mimicking previously published data in arm-reaching tasks.     

What might philosophy of science look like if chemists built it?

Had more philosophers of science come from chemistry, their thinking would have been different. I begin by looking at a typical chemical paper, in which making something is the leitmotif, and conjecture/refutation is pretty much irrelevant. What in fact might have been, might be, different? The realism of chemists is reinforced by their remarkable ability to transform matter; they buy into reductionism where it serves them, but make no real use of it. Incommensurability is taken without a blink, and actually serves. The preeminence of synthesis in chemistry could have led philosophers of science to take more seriously questions of aesthetics within science, and to find a place in aesthetics for utility. The necessary motion twixt macroscopic and microscopic views of matter in modern chemistry leads to the coexistence of symbolic and iconic representations. And in another way to the deliberate, creative violation of categories.