Final answer:
The presence of a single dissenter in Asch's conformity experiments would decrease the degree of conformity, as having an ally in dissent helps individuals resist group pressure. This disunity within the group significantly lowers the Asch effect.
Step-by-step explanation:
The presence of a single dissenter in a study modeled on Asch's classic investigation of conformity would likely decrease conformity. Asch's experiments found that when there was at least one dissenter, conformity rates dropped to near zero. This suggests that having an ally in dissent can greatly empower an individual to go against the majority. The factors that could lead someone to conform include the desire to be liked by the group or the belief that the group is more informed. However, the addition of a dissenter can provide social support for resisting conformity.
With a dissenter present, individuals are more inclined to express their independent judgments. The Asch effect, which describes the influence of the group majority on an individual's judgment, is significantly reduced when there is a lack of unanimity in the group.
When it comes to resisting conformity, factors like a single ally, keeping one's answer private, and the size of the majority influence an individual's likelihood to either conform or maintain their own judgment. Therefore, in the context of Asch's study, the correct answer to the initial question is B) Decrease conformity.