This is the question investigated by Kane & Engle, in a series of experiments with the Stroop task.
Although it may seem more parsimonious to suggest that a single mechanism - active maintenance of goal-relevant information - is responsible for Stroop performance, Kane & Engle have presented an abundance of evidence suggesting that two pieces of active maintenance may be dissociable: momentary failures to maintain the goal, and the time-consuming process of resolving competition between representations by biasing.
There are two prominent theories as to how recognition memory operates.
One theory proposes that there are two distinct processes involved in the recognition of a stimulus, called recollection and familiarity1.
And other work shows that those with low-span are more likely to succumb to the "cocktail party effect," in which a participant notices their name in an unattended stream of speach.
Those with high-span are also more able to succeed at the anti-saccade task, in which subjects must quickly look away from a sudden-onset visual stimulus.