Although the characteristics of the group members themselves are critical, they represent only the person part of the equation. To fully understand group performance, we must also consider the particulars of the group’s situation—for instance, the task that the group needs to accomplish. Let’s now consider some of the different types of tasks that might be performed by groups and how they might influence performance (Hackman & Morris, 1975; Straus, 1999).
One basic distinction concerns whether the task can be divided into smaller subtasks or has to be done as a whole. Building a car on an assembly line or painting a house is a divisible task, because each of the group members working on the job can do a separate part of the job at the same time. Groups are likely to be particularly productive on divisible tasks when the division of the work allows the group members to specialize in those tasks that they are best at performing. Writing a group term paper is facilitated if one group member is an expert typist, another is an expert at library research, and so forth. Climbing a mountain or moving a piano, on the other hand, is a unitary task, because it has to be done all at once and cannot be divided up. In this case, specialization among group members is less useful, because each group member has to work on the same task at the same time.
Another way of classifying tasks is by the way the contributions of the group members are combined. On an additive task, the inputs of each group member are added together to create the group performance, and the expected performance of the group is the sum of group members’ individual inputs. A tug of war is a good example of an additive task because the total performance of a team is expected to be the sum of all the team members’ individual efforts.
On a compensatory (averaging) task, however, the group input is combined such that the performance of the individuals is averaged rather than added. Imagine that you wanted to estimate the current temperature in your classroom, but you had no thermometer. One approach to getting an estimate would be to have each of the individuals in your class make his or her estimate of the temperature and then average the estimates together to create a group judgment. On decisions such as this, the average group judgment is likely to be more accurate than that made by most individuals (Armstrong, 2001; Surowiecki, 2004).
Another task classification involves comparing tasks in which the group performance is dependent upon the abilities of the best member or members of the group with tasks in which the group performance is dependent upon the abilities of the worst member or members of the group. When the group’s performance is determined by the best group member, we call it a disjunctive task. Consider what might happen when a group is given a complicated problem to solve, such as this horse-trading problem:
A man buys a horse for $50. He later decides he wants to sell his horse and he gets $60. He then decides to buy it back and pays $70. However, he can no longer keep it, and he sells it for $80. Did he make money, lose money, or break even? Explain why.
The correct answer to the problem is not immediately apparent, and each group member will attempt to solve the problem. With some luck, one or more of the members will discover the correct solution, and when that happens, the other members will be able to see that it is indeed the correct answer. At this point, the group as a whole has correctly solved the problem, and the performance of the group is thus determined by the ability of the best member of the group.
In contrast, on a conjunctive task, the group performance is determined by the ability of the group member who performs most poorly. Imagine an assembly line in which each individual working on the line has to insert one screw into the part being made and that the parts move down the line at a constant speed. If any one individual is substantially slower than the others, the speed of the entire line will need to be slowed down to match the capability of that individual. As another example, hiking up a mountain in a group is also conjunctive because the group must wait for the slowest hiker to catch up.
Still another distinction among tasks concerns the specific product that the group is creating and how that group output is measured. An intellective task involves the ability of the group to make a decision or a judgment and is measured by studying either the processes that the group uses to make the decision (such as how a jury arrives at a verdict) or the quality of the decision (such as whether the group is able to solve a complicated problem). A maximizing task, on the other hand, is one that involves performance that is measured by how rapidly the group works or how much of a product they are able to make (e.g., how many computer chips are manufactured on an assembly line, how many creative ideas are generated by a brainstorming group, how fast a construction crew can build a house).
Finally, we can differentiate intellective task problems for which there is an objectively correct decision from those in which there is not a clear best decision. On a criterion task, the group can see that there is a clearly correct answer to the problem that is being posed. Some examples would be finding solutions to mathematics or logic problems, such as the horse-trading problem.
On some criterion tasks, the correct answer is immediately seen as the correct one once it is found. For instance, what is the next letter in each of the following two patterns of letters?
J F M A M _
O T T F F _
In criterion problems such as this one, as soon as one of the group members finds the correct answer, the problem is solved because all the group members can see that it is correct. Criterion tasks in which the correct answer is obvious once it is found are known as “Eureka!” or “Aha!” tasks (Lorge, Fox, Davitz, & Brenner, 1958), named for the response that we have when we see the correct solution.
In other types of criterion-based tasks, there is an objectively correct answer, although that answer is not immediately obvious. For instance, consider again the horse-trading problem. In this case, there is a correct answer, but it may not be apparent to the group members even when it is proposed by one or more of them (for this reason, we might call this a “non-Eureka” task). In fact, in one study using the horse-trading problem, only 80% of the groups in which the correct answer was considered actually decided upon that answer as the correct one after the members had discussed it together.
In still other criterion-based tasks, experts must be used to assess the quality or creativity of the group’s performance. Einhorn, Hogarth, and Klempner (1977) asked groups of individuals to imagine themselves as a group of astronauts who are exploring the moon but who have become stranded from their base. The problem is to determine which of the available pieces of equipment (e.g., oxygen bottles, a rope, a knife) they should take with them as they attempt to reach the base. To assess group performance, experts on the difficulties of living in space made judgments about the quality of the group decisions. Non-Eureka tasks represent an interesting challenge for groups because even when they have found what they think is a good answer, they may still need to continue their discussion to convince themselves that their answer is the best they can do and that they can therefore stop their deliberation.
In contrast to a criterion task, in a judgmental task there is no clearly correct answer to the problem. Judgmental tasks involve such decisions as determining the innocence or guilt of an accused person in a jury or making an appropriate business decision. Because there is no objectively correct answer on judgmental tasks, the research approach usually involves studying the processes that the group uses to make the decision rather than measuring the outcome of the decision itself. Thus the question of interest on judgmental tasks is not “Did the group get the right answer?” but rather “How did the group reach its decision?” Evaluating the quality of how the decision was reached, compared with the decision itself, can be particularly challenging (Johnson & Johnson, 2012).
So, clearly the nature of the task will influence group performance and whether people perform better together, as opposed to alone. One phenomenon that dramatically illustrates these points is that of social loafing.