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Getting the right group size and the implications on businesses


All humans understand and interpret their world through the information that they assimilate and process from the external world.

Unfortunately humans can only handle so much information at once. If the information you are focusing on exceeds a particular threshold, some of this data decays.

Broadbent (1961) conceptualised a model to illustrate the way information is accessed, stored and sometimes lost.

Information is received through our sensory channels (predominantly the eyes and ears) and enters a short-term memory buffer. This buffer is hypothesised to only be able to store a limited amount of information.

5 to 7 pieces of independent information seem to be the average amount that can be stored in this short term buffer. The long-term memory store then processes and assimilates the most salient and important information contained in short term memory buffer, locking it away for future retrieval.

You can observe the Broadbent Information Processing model below:

Information --> Short term memory (buffer) --> Long term memory

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Social Implications

Your ability to process finite amounts of data is also relevant to the social information that you have to process in order to function within a society.

Just as you start to overload when raw information exceeds 7 pieces at one given time, it is argued that your processing capacity also overloads when the number of close human relationships you have reaches a certain threshold.

In his international best seller ‘The Tipping Point,’ Gladwell postulates that holding meaningful relationships with over 15 people causes overloading in much the same way as if you were asked to recall a string of random digits that exceeds 7 in length.

Human relationships are often very complicated, requiring sensitivity, empathy, intelligence, and most of all a significant amount of your time. If the 15 point threshold is exceeded, it can become very difficult to keep track of and sustain a certain level of quality within each relationship.

All close relationships require a certain level of emotional commitment, and it is understandable that the more relationships that you have the greater demand you place on yourself to maintain them.

The British anthropologist Robin Dunbar also observed limits within our social channel capacity. Dunbar identified a part of the brain called the neo-cortex that he hypothesised was responsible for complex thought and reasoning, particularly relevant for the intricacies that are involved in human relationships.

Dunbar argued that over time, as social groups and interactions within the Homo sapiens species have become increasingly complex, the brain has had to grow and evolve, to accommodate these greater social pressures.

Dunbar explained why group interactions are so intricate by pointing out that you are not only keeping track of your interactions with others, but also the relationships between other group members. Therefore if you have a group of 8 individuals, you are not only paying attention to your interactions with these 7 individuals, but also with the other 49 two way relationships between the others.

Within the group dynamic you need to understand all of the relationships between its members in order to function effectively within it.

The whole is greater than the sum of its parts; Gestalt Psychology

Within the animal kingdom humans socialise in the largest groups of all primates. This is because we are the only animals that have brains large enough to cope with the complexities of large social groups.

By observing group sizes of other primates in relation to humans, Dunbar developed an equation that calculated the expected maximum group size for that animal. What he calls the neo-cortex ratio Dunbar hypothesised that this localised region of the brain is directly proportional to the size of the animal’s largest functional group.

Using his equation he computed that ‘150 homo sapiens seems to represent the maximum number of individuals’ that we can have a social relationship with. Usually these are grouped as individuals that we would recognise and get along with.

After extrapolating this figure from his extensive research, Dunbar began noticing the regular occurrence of this number throughout past and present human societies. Here are some of the 150 group ceiling effects that have been observed:

  • Overtime military units have never exceeded 200 men
  • Some documented hunter gatherer societies have around a maximum of 150 people in their villages.
  • Some business organisations maintain a 150 maximum number of workers within each department.
  • Some religious organisations also keep within the 150 power law.
  • Why it works – A psychological explanation?

    There are a number of psychological effects at work that explain why the 150 group law is so pervasive through human culture, and why groups that exceed this threshold no longer function effectively.


    Accountability is a significant factor in determining the behaviours of others. Within a functioning group, whether it is a business organisation, a military group, or even in within a religious sect, pro-social group behaviour is often maintained by its members because of a fear of letting other group members down.

    This sense of responsibility for the well-being of others within the group is fuelled by the accountability effect:

    Small groups are essentially a kind of peer pressure: its knowing people well enough that what they think of you matters, Gladwell (2000) 

    It can be argued that any group size below the 150 ceiling point, allows the accountability effect to function successfully.

    However as groups grow beyond the 150 threshold, do these levels of accountability remain or are they weakened?

    Latene and Darley (1969) in their work examining the nature of group dynamics conceptualised; ‘that each person is only responsible for an equal proportion of effort based on the number of people in the group.’

    They observed that as group sizes grow a ‘diffusion of responsibility’ is observed within the group.

    There research supported this claim showing that individuals put less effort in, as the group size significantly increased.

    Perhaps moving beyond the 150 threshold is a tipping point that catalyses the diffusion of responsibility, causing the group to no longer function effectively as a unit.

    Arguably, group sizes that exceed 150 create a loss for the common cause that the group holds.

    In Olson’s book (1965), ‘The Logic of Collective Action’, it is argued that “the larger a group is the farther it will fall short of providing supply of any collective good.”

    Implications for businesses

    Within institutions it is important that group sizes do not exceed the 150 threshold. When accountability effects lose their strength you increase the likelihood that the workers will develop a number of the following characteristics:

  • A reduced work-ethic effort.
  • A sense of apathy towards the collective goal.
  • An increased likelihood of committing anti-social behaviour.
  • A lack of empathy and understanding towards other group members.
  • The cultivation of a self-serving mindset.
  • The bigger the group grows the less accountable individuals become to one another, creating a breeding ground for anti social and irresponsible behaviour:

    When group sizes become relatively large there is a danger that group members lose touch with their personal morals and values.

    There are many documented instances from around the world where members of a group have often been reported to lose their personal identity in replacement of a group identity.

    When group sizes grow beyond the 150 mark, there is an increased likelihood that personal choice and control is lost in favour of the groups intentions and wishes.

    Whether or not the group identity is harnessed in a positive or negative way depends very much on the nature of the group. Certainly in professional settings, having a team that exceeds the 150 level is ill advised because the group’s functioning can become unpredictable and uncontrollable.

    Example of a company that abides by the 150 principle

    In ‘The Tipping Point’ Gladwell highlights how the privately held multi million pound high-tech company ‘Gore Associates,’ applies the 150 group size rule with great effectiveness.

    Through trial and error the company realised the organisation became less efficient when working groups exceeded the 150 mark:

    We found again and again that things get clumsy when group numbers exceed hundred and fifty, Bill Gore cited in ‘The Tipping Point’ (2000).

    The moment that one of the company’s plants exceeded 150 employees, Gore knew it was time to build a new plant. The plant was no more than 20 miles away from one another, but far away enough for each plant to cultivate its own identity and independence.

    By keeping within the 150 mark, everyone within each plant knew everyone else. Gore had cultivated such a strong community spirit with every group member creating a well defined sense of responsibility and accountability within the company.

    When enterprises share strong common personal relationships within their organisation, you not only learn about the ideas, beliefs, and facts that the company has, but you also develop a strong understanding of what your colleagues know or don’t know.

    Through knowing the beliefs, preferences, and the predispositions of others you build an efficient working relationship that plays to the individual’s strengths.

    For example if you need a strong negotiator to close a deal, and you have a group of employees to chose from holding an explicit understanding of each member's strengths and weaknesses you can get the right person for the job.

    Daniel Wegener labels the phenomena as “transactive memory,” where people are not just aware of what they know, but also what other people know.

    When group sizes exceed 150 it can be argued that transactive memory becomes increasingly difficult to utilise because it almost becomes impossible to maintain a current inventory of everyone’s skill sets.

    Here are some of the benefits of transactive memory:

  • Faster response time to deal with customers.
  • Greater level of cooperation within the group.
  • Stronger relationships, creating a more understanding and enjoyable working environment.
  • Greater ability to overcome obstacles as a team.
  • Increased ability to innovate.
  • Onto Part Two

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