What if social behavior could be boiled down to four distinct styles? That's sometimes the conclusion drawn from the work of industrial psychologists David W. Merrill and Roger Reid. If the conclusion were valid, that would make interpersonal relations pretty straightforward. You'd have only four personality types to deal with. But the reality isn't so simple. The work of Merrill and Reid is all the more useful for being more detailed and complex.

Merrill and Reid provide a useful way of analyzing and describing different social styles. Psychiatrists deal with the full complexity of the mind, including historical factors like childhood trauma, that shapes an individual personality. Industrial psychologists are less concerned with the inner mind and more concerned with behavior. In the workplace, it doesn't really matter so much why a given person is an effective leader. What's more useful is an analysis of individual behavior – how, rather than why, that leader is effective.

Merrill and Reid begin by describing two behavioral characteristics: assertiveness and responsiveness. They evaluate each characteristic on a scale from low to high. Highly assertive personalities tell rather than ask; they often make good leaders. Individuals who rank low on assertiveness scale on the other hand tend to avoid risk and are more inclined to ask than to demand. They tend to be team players. Overall, the assertiveness scale describes how the individual communicates with others.

Where an individual ranks in the responsiveness scale describes how an individual responds to communications from others, particularly their requests and demands. Individuals who rank high on the responsiveness scale are "people persons" who get along well with others. Those who rank low tend to be less sociable and more occupied with tasks than engaged with coworkers. They're focused, but not necessarily people persons.

Merrill and Reid combine these two scales of assertiveness and responsiveness to create four behavioral areas. Here's how this works:

An individual who scores low on both the responsiveness scale and assertiveness scales is analytic. He may not respond easily to suggestions, but keeps his opinion to himself. He can be a bit of a loner. This is the guy who comes to the neighborhood meeting, offers no suggestions and pretty much ignores whatever the group decides. In the workplace, he's more likely to be a programmer or a tech than a leader. The weak spot for analytics is that they can get a little scratchy if their opinions are challenged.

Someone who scores high on the responsiveness scale and low on the assertiveness scale is expressive – the artistic type. In the workplace, such a person may be a "creative" who neither asserts her own opinion nor is greatly influenced by the opinions of others. She "does her own thing," concentrating on her own creative output and leaving the big decisions to the suits. She's the neighbor who paints her house a vibrant purple with orange trim and is a little surprised that her neighbors don't like it. Impulsiveness is the weak spot for expressives.

A person who scores low on the assertiveness scale and high on the responsiveness is amiable. Someone exhibiting amiable social behavior is likely to "go along to get along" and may hesitate to put forth his own opinion if it differs from the opinion of the group. As the name suggests, amiables are easy to get along with, but they're not going to stick their necks out. They'll let someone else decide.

Someone who scores high on the assertiveness scale and low on the responsiveness scale is a driver, the take-charge kind of person who can make a good leader. Drivers come up with great ideas and push them to a conclusion. They enjoy leading; just don't get in their way. From all accounts, Steve Jobs may be the archetypal driver.

Because each of these variables weighs differently in a given personality, the Merrill and Reid social styles analysis can be used to describe a nearly infinite number of social types.