How does groupthink negatively impact decision-making?

Groupthink negatively impacts decision-making primarily by suppressing dissenting viewpoints in favor of achieving consensus within a group. In this phenomenon, the desire for harmony and conformity among group members can lead to a deterioration in mental efficiency, reality testing, and moral judgment. When individuals feel pressured to agree with the majority, they may withhold their own opinions or concerns, resulting in a lack of critical evaluation of the ideas presented. This can lead to poor decision-making, as critical insights or alternative solutions may be overlooked, and the group may proceed with a flawed plan without fully considering potential risks or downsides.

The other choices illustrate elements that do not reflect the nature of groupthink. Increasing the quality of discussions, facilitating open critique of ideas, and ensuring all voices are heard equally are characteristics of healthy group dynamics, rather than the conformist tendencies that define groupthink. In fact, those characteristics are typically diminished in a groupthink scenario, highlighting why the selected answer accurately captures the detrimental effects of this phenomenon on decision-making processes.