Final answer:
Machiavellianism has a negative relationship with leadership effectiveness due to its manipulative characteristics, which are contrary to follower-oriented and altruistic leadership styles.
Step-by-step explanation:
The interpersonal trait that has research showing a negative relationship with leadership effectiveness is Machiavellianism. This trait is often characterized by manipulation and exploitation of others, a lack of morality, and a focus on self-interest rather than mutual benefit or organizational goals.
Such characteristics contradict the principles of socialized charismatic leadership, which tends to be altruistic and follower-oriented.
Leaders with Machiavellian tendencies tend to have difficulties in forming positive, effective leadership relationships because they may value personal gain over collective interests and utilize power for personal ends, therefore hindering organizational cohesiveness and trust within their teams.