7. The Methods of Experimental Psychology
It is plainly evident that matching the right person to the job first requires determining the mental qualities that are necessary for success at that particular job. Thus far, the methods for doing so have been largely theoretical - making assumptions and applying common sense - and that has been sufficient to lead us a few steps in the right direction, but no further.
Little experimentation is needed to determine that, for example, a person who is colorblind is ill-suited to certain positions in the railroad industry because determining whether a signal is red or green is critical. We might also conclude that a person who is colorblind is ill suited to working in a dyeing operation. But does the inability to distinguish between the red fruit and green leaves preclude such a person from being a Gardner or a farmer? This seems arguable, and in instances such as these a more objective experimental method is necessary to make an evidence-based determination.
Another flaw of the common-sense approach is that it can only consider the action and the actor as an undivided whole, which adds another layer of assumption and speculation. Instead, we should approach the examination of mental capacities in the same ways as physical: to reduce a process to its component actions and examine the manner in which a given quality can contribute to success in each of these components.
But there is much to be missed in this method of dissection if we fail to adequately identify the manner in which multiple characteristics support one another. It is much like considering the gears in a complex machine - in which each is important unto itself, but their collective performance requires more than perfection in each part, as they must work together in a system. Recall to the previous example of the ball-bearing factory that considered only manual dexterity and ignored visual acuity.
Particularly in the area of psychology, individual functions are merely segments of an entire mental profile. Capacities such as attentiveness, creativity, memory, and intelligence are interdependent, such that it is insufficient to consider the operations in a divided and independent manner, were it even possible to contrive a way to do so.
There is also the matter of causation: a man who happens to have a given capability can also happen to be efficient in a given line of work, but this is mere correlation and there may not be a causal connection between one and another. Mere correlation is particularly dangerous because it leads us to act with confidence in fallacy and dismiss a more accurate analysis.
Realizing that all of this is abstract and theoretical, Munsterberg states his intent to consider more specific examples in the next few chapters.