Proceedings of the Annual Meeting of the Cognitive Science Society

This paper proposes a Bayesian account of asymmetriesfound in speech perception: In many languages, listenersshow greater sensitivity if a non-coronal sound (/b/, /p/, /g/,/k/) is changed to coronal sounds (/d/, /t/) than vice versa. Thecurrently predominant explanation for these asymmetries isthat they reflect innate constraints from Universal Grammar.Alternatively, we propose that the asymmetries could simplyarise from optimal inference given the statistical properties ofdifferent speech categories of the listener’s native language.In the framework of Bayesian inference, we examined twostatistical parameters of coronal and non-coronal sounds:frequencies of occurrence and variance in articulation. In thelanguages in which perceptual asymmetries have been found,coronal sounds are either more frequent or more variable thannon-coronal sounds. Given such differences, an ideal observeris more likely to perceive a non-coronal speech signal as acoronal segment than vice versa. Thus, the perceptualasymmetries can be explained as a natural consequence ofprobabilistic inference. The coronal/non-coronal asymmetryis similar to asymmetries observed in many other cognitivedomains. Thus, we argue that it is more parsimonious toexplain this asymmetry as one of many similar asymmetriesfound in cognitive processing, rather than a linguistic-specific, innate constraint.