Not surprisingly, most of us act as if we are dealing with logical, rational thinking co-workers, be they colleagues or managers. Yet when we remember that every decision we make is taken at an emotional level first and only then rationalised and supported by logic, it stands to reason that they behave for at least some of the time in an illogical way.
Putting a visual framework on that, it's as if they are each two beings in one. Much as their 'emotionally' driven old-brains are inter-linked in many ways to the higher level cortex (which by its size alone makes us uniquely human), they often act as if they were distinct entities.
I find it helps to imagine people as double-brained beings when I interact with them; a rational thinking part which we all pretend to be and a strangely predictable instinctive part which can bring on emotions as varied as being loving and caring to being spiteful and dishonest.
Try imagining your office colleagues as horses and riders; the horse representing their instinctive older brain and their persona as a rider being the rational 'in-control' part we'd all like to think that we are. It would lead to a crowded office but it might explain some of the daily misunderstandings! More at: http://www.lazyhorses.com/the-horse-and-rider.html

If we were really rational beings… ?

Much of what we do is arguable rational, and the way governments and economists see us is as rational thinking machines. To them we are (or should behave) all like Mr Spock clones in a Startrek remake. 
Even HR departments try to build as much rationality into their departments as possible… the Head of Finance is often asked to only see the world in those terms. And the fact is that if Mr.Spock were to run any department, it would be as Finance Director that he would have the best chance for success… at least if he never had to take a risk or deal with staffing issues.

But I think it’s pretty obvious to most of us that we are not first and foremost rational beings. Indeed, today’s financial led crisis probably would not have happened if the bankers testosterone fueled decisions had not been grounded in so-called rationality. Yet logic and value are trusted and we still mistrust emotion.