We discuss the conventionalization process in Central Taurus Sign Language (CTSL), an emerging sign language in its initial stages, and present evidence from four studies for the amount of lexical and structural variation it harbors. The four studies together portray the architecture of a young system under construction. Study 1 looks at signs for everyday objects and finds considerable variation in their degree of conventionalization. Study 2 examines modifier-head and negation-head relationships, showing substantial conventionalization. Study 3 addresses the emergence and conventionalization of various word orders as argument structure markers. It shows that conventionalization increases over successive cohorts of signers, but it decreases as argument structure becomes more complex. Study 4 demonstrates the emergence and conventionalization of distinctive morphological markers to signal the subtle semantics of symmetry and reciprocity. Finally, we raise the issue of whether CTSL presents evidence of syntactic structure, or whether its properties can be characterized in terms of a simpler “linear grammar” that maps directly between phonology and semantics.

When referring to objects, speakers are often more specific than necessary for the purpose of establishing unique reference, e.g., by producing redundant modifiers. A computational model of referring expression production that accounts for many of the key patterns in redundant adjectival modification assumes that adjectives differ in how noisy (reliable), and consequently, how useful they are for reference. Here we investigate one hypothesis about the source of the assumed adjectival noise: that it reflects the perceptual difficulty of establishing whether the property denoted by the adjective holds of the contextually relevant objects. In Exp.1, we collect perceptual difficulty norms for items that vary in color and material. In Exp. 2, we test the highest (material) and lowest (color) perceptual difficulty items in a reference game and find that material is indeed less likely to be mentioned redundantly, replicating previous work. In Exp. 3, we obtain norms for the tested items in a second perceptual difficulty measure with the aim of testing the effect of perceptual difficulty within property type. The overall results provide preliminary support for the hypothesis that the propensity to redundantly use color over material adjectives may be driven by the relative ease of assessing an object’s color, compared to the relative difficulty of assessing its material.