‘The [individual’s] early adaptation by the means of splitting [is] not an expression of cowardice, but…really his only chance of survival, to escape his fear of annihilation.’
Alice Miller, ‘The Drama Of Being A Child.’
Infants and toddlers (aged from approximately eighteen months to thirty-six months old) find it extremely hard to tolerate ambiguity and ambivalence. For this reason, their perception of features of the external world becomes polarized, or, as it is often, informally and metaphorically put, ‘black and white’. Like the BPD sufferer, they practice a mental phenomenon known as splitting.
For the infant/toddler (18 – 36 months, approx.) then, what we might call ‘grey areas’ are effectively eliminated as everything including, most significantly, the infant’s / toddler’s mother (or primary carer) is CATEGORIZED, UTILIZING THE SPLITTING PROCESS, AS EITHER ‘GOOD’ OR ‘BAD’, depending upon how she is behaving in relation to him/her at any given point in time.
When the mother fails to satisfy adequately the infant’s needs, s/he perceives her as ‘all bad” (i.e. the baby splits his perception of her). And, in stark contrast, when the mother DOES satisfy the infant’s needs (e.g. with a satisfying feed or by providing appropriate physical comfort) s/he perceives her as ‘all good. It is only as the child gets older and develops and his/her understanding of the world and of those who inhabit it becomes increasingly sophisticated that s/he is able to integrate such contrasting perceptions and come to realize that both good and bad elements can exist in the same person simultaneously.
However, the adult sufferer of borderline personality disorder (BPD) becomes stuck in this toddler-like state of seeing others as either all good or all bad and, as a result, forms extremely unstable relationships with others, particularly significant others, perpetually vacillating between idealizing them and demonising them; this phenomenon is known as SPLITTING and, in essence, is a defence mechanism serving to protect the individual with BPD from feelings of potentially overwhelming anxiety
Finally, it is worth pointing out that it is not just people with BPD who employ the defence mechanism of ‘splitting’; for example, adolescents tend to do so quite a lot. Adults who do have BPD and who are not mentally ill use it too. However, in the case of those suffering from BPD, the defence mechanism of ‘splitting’ is used abnormally frequently in comparison to the average individual and the extremes in which they perceive others vacillate more dramatically. (NB Although I employ the term ‘used’, defence mechanisms are UNCONSCIOUS processes i.e. the BPD sufferer does not deliberately choose to exercise the psychological response of ‘splitting’).
A leading treatment for BPD is, currently, dialectical behaviour therapy.