  Words shift in meaning for many reasons, including cultural factors like new
technologies and regular linguistic processes like subjectification.
Understanding the evolution of language and culture requires disentangling
these underlying causes. Here we show how two different distributional measures
can be used to detect two different types of semantic change. The first
measure, which has been used in many previous works, analyzes global shifts in
a word's distributional semantics, it is sensitive to changes due to regular
processes of linguistic drift, such as the semantic generalization of promise
("I promise." -> "It promised to be exciting."). The second measure, which we
develop here, focuses on local changes to a word's nearest semantic neighbors;
it is more sensitive to cultural shifts, such as the change in the meaning of
cell ("prison cell" -> "cell phone"). Comparing measurements made by these two
methods allows researchers to determine whether changes are more cultural or
linguistic in nature, a distinction that is essential for work in the digital
humanities and historical linguistics.
