It is difficult to chart “normal movements” in atypical populations, such as those with Parkinson's disease, because there is great variability in the pattern of motor changes, both within and between patients. However, the potential clinical implications of Latash & Anson's theme are positive and powerful.

We outline some ways in which motor neglect (the underutilization of a limb despite adequate strength) and hysterical paralysis (failure to move a limb despite no relevant structural damage or disease) may throw light on the pathophysiology of catatonia. We also comment on the manifold inadequacies of distinguishing too firmly between symptoms of “neurologic origin” and of “psychiatric origin.”

Wynn's claims are, in principle, entirely reasonable; although, as always, the devil is in the details. With respect to Wynn's discussion of the cultural evolution of artifactual symmetry, we provide a few more arguments for the utility of mirror symmetry and extend the enquiry into the tacit and explicit processing of natural and artifactual symmetry.

Parkinson's Disease (PD) is a neurological disorder which appears to be increasing in prevalence in the Asia-Pacific region among the elderly. Although PD is considered by many as a motor syndrome, its physiological basis in dopaminergic pathways has recently been associated with cognitive and neurolinguistic changes. This paper attempts to synthesise the common threads running through clinical and empirical work which has supported a specific cognitive word-finding deficit in PD. Recent computational accounts of the observed deficits are also reviewed as one way of testing theories of PD-like lexical-semantic errors, and generating empirically-testable hypotheses.