It has been said by John Watson, as well as other 'tabula rasa'(blank slate) theorists as early as the seventeenth century, that the individual is the sum total of his past learning history(of all his interactions with the environment). I don't believe that there has, so far, been a satisfactory personality theory based on this assumption. I believe that the personality theory presented in this article is more than satisfactory, I believe it is virtually unassailable. I can only make this claim because I consider this model a hypothetical construct to be refined, and completed, rather than as an absolute. I must admit(with pride, not reticence) that this model was derived from reason, logic, conceptualization and introspection along with a heavy dose of the aforementioned "tough-minded behaviourism". This is consistent with two invaluable recent trends in psychology: a cognitive behaviourism, and the long needed merging of the humanist-behaviourist movements.

   In the last hundred years or so a number of interesting, even useful, personality theories have been offered by adherents of the various 'schools' of psychology and psychiatry. In general, these theories have shown considerable insight into the human condition, but none has ever dealt sufficiently with the full range and complexity of variables which influence human development. A theoretical construct of personality development was needed which provided a mechanism by which we could come to objectively understand the influences, both within and without, which determine the course of our development. Without this knowledge we would never be able to gain control over our own development by utilizing to its maximum the great potential of our free will.

   It is necessary to consider all of the variables in the environment influencing the development of the personality; and it appears that three sources of input include all of these variables. Of the three sources of input the first, physical environment, is largely self-explanatory. What must be explained is why interpersonal communication is considered as a separate source of input rather than as part of the physical environment. At this point it might be of benefit to diagram the three sources of input in relation to an individual personality.

Note: the physical environment impinges directly on our various sensory inputs. 

Note: Personality B can only communicate(impinge on the sensory inputs) with Personality A through the manipulation of the physical environment: but; the source self is not empirically observable, rather it is an abstract concept.

Note: inner speech originates within Personality A, becomes a conscious process through entering the perception: and, as do the other sources, affects the total past learning history(TPLH).  

     In addition to considering the affect these three sources of input have on the development of the personality, this model of personality development makes one further, all important consideration; and that is we must consider a concept of perception. In essence this says we are not effected by our environment; but instead, by our perception of the environment. As an example, consider two people who arrive at a meeting late; they both step through the doorway at the same time; all those at the meeting stop what they are doing and look at the late arrivals. One may perceive what is occurring as indicative of negative feedback(input), that the people present are critical of the late arrival; and, the other may perceive this situation as positive feedback(input), that the people present consider the late arrival to be appropriately fashionable . On the basis of this input the first may resolve never again to be late at a meeting, while the second may find himself arriving late more often. This result could be independent of the true feelings of those already present at the meeting.  Of course the reason the two persons(personalities) perceived and responded to an identical environmental situation differently is that the two individuals brought to that environment vastly different past learning histories. Not only does our past learning history affect our behaviour, but it also affects our perceptions of the environment.

     Each input, from whatever source that enters the individual's perception, has an effect greater than zero on the TPLH; and, each change in the TPLH has an effect greater than zero on the individual's perception. The effect of any perceived input while always greater than zero will have a range of effect from negligible to all pervasive. Of course many, perhaps most, of the inputs from the environment will have a negligible effect on the TPLH, but it is possible for a single input to have such great significance as to result in a major change in the course of the development of the personality. It is also the case that any change in the TPLH has the same possible range of effect on the perception of future inputs from the environment.

     I am not disclaiming the effects of our spirituality, physiology, biochemistry, or heredity; but, their effect is determined by our perception of them and how they alter our interactions with the environment. In the purest theoretical sense, with this 'tabula rasa' personality construct, we would have to say that there is a time, probably prenataly, when the first sensory input, probably from the physical environment, is perceived, processed, and stored. The early inputs would have a greater effect than the later ones since they have less past learning history to dilute their effect, and they would also have a greater effect because they would be more influential in determining the perception of future inputs from the environment. This would account for the presumption common to most personality theories that the basic personality is formed in the very early years of childhood.

     This theoretical model addresses several of the major, but simplistic, challenges to and reservations about behaviourism. One reservation is the idea that behaviourism is a tautology since we define our stimuli by their effect on the responses they are made contingent upon. This is answered in theory, although not in practice(due to the state of the technology) by the fact that it would be possible to determine 'a priori' with absolute certainty, the effect of any stimulus in any contingent relationship with a response if we fully knew the total past learning history of that individual.

     A second much asked question is how two people who grow up in a seemingly identical environment can become two very different people? Those who would ask such a question are taking a naive view of the environmental variables affecting human development; and, based on this model they have probably neglected to consider the input from source three, inner speech, Additionally, they have not considered that the inputs from the so-called 'identical' environments have been mediated by each individual's unique perception of that environment.  

     A third and very compelling reservation about behaviourism is that the practical application of the theory, while changing behaviour, does not change the 'inner' person; and, it is less than a true therapeutic agent. I think it is clear from this learning based personality theory that as we affect the individual's behaviour by a manipulation of environmental variables, we are affecting the 'inner' person, the personality. I would agree, though, that since behaviourists have largely ignored the inner being, they have not been nearly so effective as they could be in developing behavioural generalization from the therapeutic environment to the outside world.