Non-adjacent agreement attraction
I must have seen this ad at least a dozen times before I even noticed the agreement attraction:
Studying micro-climates like this have helped me to understand if it’s gonna be a minor event, or a catastrophic one.
Partly, I didn’t notice it because it wasn’t exactly an ad that I was paying a whole lot of attention to. But partly, it was probably because the sentence is very natural to me, especially for spoken language. What is interesting about the example, beyond just its grammaticality, is the fact that the trigger for plural agreement (micro-climates) is not linearly adjacent to the verb.
In Marcel Den Dikken’s (2001) paper on pluringulars, he cites Richard Kayne for the observation that agreement attraction does not require adjacency of the trigger to the verb. Kayne’s example involved a possessor, The participants’ identity are to remain a secret.