Sign languages employ iconic strategies in their morphology in expressing spatial relations. These strategies, while iconic, are incorporated into the grammatical system and follow certain linguistic rules. One environment where we see an extensive use of iconic morphology is the instrumental classifier predicate. The three sign languages studied in this dissertation, American Sign Language (ASL), Hong Kong Sign Language (HKSL) and Turkish Sign Language (TiD), although unrelated, use the same two iconic morphological strategies as their main means to encode instrumental classifier predicates: (i) Handling iconicity, where the linguistic articulator hand represents the body part hand, and (ii) Object iconicity, where the linguistic articulator hand represents some physical property of an object other than the body part hand. While these two strategies are available to the morphologies of all three sign languages, they use them in different quantities and in different ways. I argue that these differences are a result of typological differences among the three languages.The main purposes of this dissertation are to describe the environments in which these two strategies are observed and to offer an explanation to why one type of iconic strategy is more strongly associated with certain environments than the other. I do this by investigating a controlled set of experiments with the help of analytical tools from Information Theory, psychology, and statistics. My findings show that, with respect to classifier predicates, HKSL and TiD behave more similarly to one another than ASL does to either language. I call the former two languages ‘Iconic Agreement’ languages, and ASL a ‘Grammatical Agreement’ language. Iconic Agreement languages are typically highly sensitive to the perceptually salient components of an event in choosing the suitable iconic type for its description. In these languages, Handling and Object strategies have a more diffuse distribution than Grammatical Agreement languages such as ASL, where the two strategies have a more clearly defined set of grammatical duties than the ones in Iconic Agreement languages. These grammatical duties include marking agency (Handling iconicity) and unaccusativity (Object iconicity). Iconic Agreement languages, on the other hand, follow a series of filters in determining the morphological strategy in the classifier predicate. These filters include lexical conventionalization, typicality, and event semantics. Moreover, my findings show that while the tendencies point to a typological distinction, in the two proposed language types we can still see the effects of the other, albeit at a lesser degree. This has implications for the interlacing status of the gestural modality with the language faculty. This dissertation offers ways in which this stochastic nature of the two types of grammar can be exploited to offer insightful explanations to the forces that shape them.