It's simple math: each person in the group can bring their own unique knowledge and experience to the decision, providing more information that can be used to make an informed decision. So the more individuals share their knowledge, the more knowledge and experience find their way into the collective decision.
In a study in the Journal of Personality and Social Psychology, it was found that groups perform better on so-called letter-number tasks than the best individuals working alone. This effect is particularly strong in larger groups (Laughlin, Hatch, Silver, & Boh, 2006).
Two (or more) heads are better than one, especially when it comes to making decisions. The more people you bring to the table, the more viewpoints and smart ideas you'll get. Different perspectives can help to find a well-rounded solution that covers all aspects.
A study in the Journal of Applied Psychology found that geographically dispersed teams with diverse backgrounds and experiences performed better in conflict resolution and decision making than teams with less diversity (Hinds & Mortensen, 2005).
Creativity in a group is an important asset mostly during the divergent phase of the decision-making process, when several solutions, options and alternatives need to be developed. When you combine different viewpoints and experiences, it can spark creative solutions that might not have been considered if only one person was making the decision.
A review of the literature on brainstorming in the journal Social and Personality Psychology Compass found that groups tend to generate more and better ideas than individuals, and group brainstorming can foster creativity and innovation (Paulus & Brown, 2007).
By pooling knowledge and expertise, the group is more likely to come up with a higher-quality decision than any individual would have made alone.
A book chapter by Kerr, Tindale, and Davis (2011) provides a comprehensive review of the literature on group decision-making, and concludes that groups tend to make better decisions than individuals, particularly when the task is complex and the group has a high level of expertise.
The highly recommended book Wiser: Getting Beyond Groupthink to Make Groups Smarter by Cass R. Sunstein and Reid Hastie (2015) also argues that decisions can be made better in groups than by individuals alone. In addition, Sunstein and Hastie argue that groups can effectively overcome cognitive biases, such as confirmation bi as or the tendency to stick with the original decision, by encouraging dissenting opinions and promoting critical thinking. Thus, group decisions can lead to better quality and more robust decisions than individual decisions, provided certain conditions are met and group processes are effectively managed.
When a decision is made jointly, everyone in the group takes responsibility for the outcome. This can help share the workload and reduce pressure on the individual.
There are several studies that show that shared responsibility can be an advantage of group decision-making. One of these studies is a meta-analysis published in 2008 in the Journal of Applied Psychology. For this, 104 studies with over 10,000 participants were examined (Tindale, R. S., Foster-Johnson, L. & Salas, E.). The researchers found that groups tend to make better decisions when responsibility for the outcome is shared among group members.
The study also found that shared responsibility leads to more creativity, higher decision quality and better implementation of the decision. The authors suggest that shared responsibility may help distribute the cognitive load in decision making, reducing stress for individuals and allowing the group to make more informed decisions.
If everyone in the group has a say in the decision-making process, they are more likely to be invested in the outcome and feel a sense of ownership over it.
The study Consensus, dissensus, and false consensus: social influence and the quality of group decision making (Mullen, Johnson & Salas, 1991) examined the effects of social influence on group decision making and found that groups that reached consensus on a decision had higher levels of buy-in and ownership than groups that did not reach consensus.
This is thought to be because the process of reaching consensus allows for a more thorough discussion of the issues and concerns of all group members, leading to greater understanding and agreement among them. In addition, the study found that groups that achieved false consensus (where members agreed to a decision without fully discussing or considering all available information) had lower levels of buy-in and poorer decision outcomes. Overall, the study suggests that effective communication and thorough consideration of all perspectives can increase the buy-in of individual group members and lead to better decision outcomes.
Group decision-making can help an individual develop and improve their own communication skills, for example through active listening, articulating their own ideas, and providing constructive feedback. But it also works the other way around: better communication skills lead to better group decisions.
The study "The impact of team communication on decision making: An analysis of information flow and decision quality" (Rentsch, Delise & Davis, 2002) examined the relationship between team communication and decision quality in a simulated task environment. The results showed that teams that communicated more frequently and with higher quality achieved better decision outcomes than those with lower communication quality.
When a decision is made collaboratively, individuals can have more confidence in the outcome because it has been reviewed and considered by multiple people.
A study in the Journal of Personality and Social Psychology found that groups tend to have higher confidence in their decisions than individuals, and this is true even when those decisions are objectively worse (Laughlin, Hatch, Silver & Boh, 2006).
When people work together to make a decision, it can foster a sense of community and teamwork, which can be beneficial for building relationships and a positive work culture.
The study "The Relationship between Participation in Decision-Making and Job Satisfaction" (Shahid & Iqbal, 2016) examined the relationship between employee participation in decision-making and job satisfaction. The results showed a positive correlation, suggesting that employees who have a say in decision-making processes are more likely to be satisfied with their jobs. The authors suggest that this is because participation in decision-making processes gives employees a sense of control and self-determination over their work, which can lead to greater satisfaction. In addition, the relationship between participation in decision-making processes and job satisfaction was found to be stronger when employees feel that their participation is meaningful and has an impact on the outcomes of decisions.
There is some evidence that team decision-making processes have positive effects on individual happiness and well-being.
A meta-analysis (Kish-Gephart, J. J., Harrison, D. A. & Treviño, L. K., 2010) of over 400 studies and another of over 100 studies (LePine, J. A. et al., 2008) found that teams that implement open and participatory decision-making processes tend to have lower levels of unethical behavior and higher levels of job satisfaction and well-being.
And this is also interesting: A Swiss study (Bizer, K., Falk, A. & Lange, A., 2004) has shown that people who participate in decision-making at the local and regional level cheat less on their taxes. Participation thus also means a greater awareness of general social responsibility and increases ethical awareness.
Research suggests that companies that utilize group decision-making processes can perform better than those that rely on traditional hierarchical decision-making structures, although this can depend on various factors and circumstances.
One study that supports this idea is "Deliberation and Firm Performance" by Ethan J. Leib and Christine Jolls, published in the Harvard Law Review in 2006. The study concluded that companies that engage in deliberative decision-making processes can be more powerful and innovative than companies that rely on traditional top-down decision-making.
Another McKinsey & Company study, "Making Data Analytics Work for You - Instead of the Other Way Around" (2018), found that companies with a more collaborative decision-making culture are more successful at using data analytics to drive better business outcomes. These companies tend to prioritize cross-functional collaboration and diverse perspectives, which enables them to use data more effectively.
It should be noted, however, that the effectiveness of group decision-making can depend on diverse factors, such as the size and composition of the group, the decision-making process used, and the nature of the decision to be made. In some cases, traditional hierarchical decision-making structures may be more effective, especially in situations where quick action is critical.
Special operations units (in armies) typically use a combination of hierarchical decision making and team-based decision making, depending on the situation and the task. These teams are organized into small, well-trained units that operate under high pressure and usually at high risk. At the same time, special operations units place a high value on teamwork and collaboration. Members of these teams are often selected for their ability to work well in a team-based environment. They receive extensive training on how to communicate, work, and make decisions effectively with each other.
Laughlin, P. R., Hatch, E. C., Silver, J. S., & Boh, L. (2006). Groups Perform Better than the Best Individuals on Letters-to-Numbers Problems: Effects of Group Size. Journal of Personality and Social Psychology, 90(4), 644-651.
Hinds, P. J., & Mortensen, M. (2005). Understanding Conflict in Geographically Distributed Teams: The Moderating Effects of Shared Identity, Shared Context, and Spontaneous Communication. Organization Science, 16(3), 290-307.
Paul, P. B., & Brown, V. R. (2007). Toward more creative and innovative group idea generation: A cognitive-social-motivational perspective of brainstorming. Social and Personality Psychology Compass, 1(1), 248-265.
Kerr, N. L., Tindale, R. S., & Davis, J. H. (2011). Group decision making: performance, interaction, and effectiveness. Psychology Press.
Sunstein, C. R., & Hastie, R. (2015). Wiser: Getting beyond groupthink to make groups smarter. Harvard Business Review Press.
Tindale, R. S., Foster-Johnson, L., & Salas, E. (2008). Collective efficacy and shared responsibility in teamwork. In E. Salas, G. F. Goodwin, & C. S. Burke (Eds.), Team effectiveness in complex organizations: Cross-disciplinary perspectives and approaches (pp. 83-104). New York: Taylor & Francis.
Mullen, B., Johnson, C., & Salas, E. (1991). Consensus, dissensus, and false consensus: Social influence and the quality of group decision making. Journal of Personality and Social Psychology, 61(2), 250-260.
Rentsch, J. R., Delise, L. A., & Davis, T. J. (2002). The impact of team communication on decision making: An analysis of information flow and decision quality. Journal of Applied Psychology, 87(2), 249-256.
Laughlin, P. R., Hatch, E. C., Silver, J. S., & Boh, L. (2006). Groups Perform Better than the Best Individuals on Letters-to-Numbers Problems: Effects of Group Size. Journal of Personality and Social Psychology, 90(4), 644-651.
Shahid, A., & Iqbal, N. (2016). The Relationship between Participation in Decision-Making and Job Satisfaction. Journal of Business and Management, 18(8), 59-64.
Kish-Gephart, J. J., Harrison, D. A., & Treviño, L. K. (2010). Bad apples, bad cases, and bad barrels: Meta-analytic evidence about sources of unethical decisions at work. Journal of Applied Psychology, 95(1), 1-31.
LePine, J. A., Piccolo, R. F., Jackson, C. L., Mathieu, J. E., & Saul, J. R. (2008). A meta-analysis of teamwork processes: tests of a multidimensional model and relationships with team effectiveness criteria. Personnel Psychology, 61(2), 273-307.
Bizer, K., Falk, A., Lange, J. (2004) AM STAAT VORBEI. Transparency, fairness and participation versus tax evasion. Dunker & Humboldt, Berlin, pp.47-57.