How does the punctuation of “A Narrow Fellow in the Grass” affect its meaning?

Emily Dickinson was a master at utilizing punctuation to increase the ambiguity of her poems. "A Narrow Fellow in the Grass" is a perfect example of this rule, as Dickinson employs her trademark dashes to increase both the choppiness of the poem's rhythm and its ambiguity. Take, for instance, the first stanza:

A narrow Fellow in the Grass
Occasionally rides -
You may have met him? Did you not
His notice instant is - 

The dashes in this stanza encourage hard stops that dislocate the rhythm from a regular pattern. Additionally, the dashes make much of the central meaning of the excerpt hard to determine. For example, the dash at the end of the last line could be simply a hard stop ending Dickinson's statement that the "fellow" is noticed instantly. From another point of view, however, we could see the dash as an interruption that prevents Dickinson from explaining what "his notice instant" is. Indeed, we could surmise that Dickinson was about to tell us what this "notice instant" is, but she's cut off before she can finish her statement. This choppy ambiguity is a classic characteristic of Dickinson's poetry, and one of the reasons she was such a brilliant poet.