Many attempts have been made to carry forward, refine or break up the syndromes described by the two conceptual giants. One motive was to improve earlier formulations of the fundamental characteristics that might underlie all the others.  Berze (1914/1987), for example, drew on Griesinger’s ‘lowered mental energy’ to postulate a basic factor, described in terms of a primary insufficiency of mental activity. This negative factor was responsible for the secondary positive phenomena as in Bleuler’s theory, but without the psychic complexes. The mechanism was similar to that in Jackson’s (1869/1932) theory of a hierarchy of levels of functional organization in the nervous system.  A (negative) loss of function higher up can result in a (positive) disturbance of functions lower down. Gruhle (1929) pointed to the difficulty of applying such explanations to the phenomena of schizophrenia. He also made the unexceptionable, but rarely heeded,  comment that some experiences and behaviours in schizophrenia cannot easily be fitted into either category.

Gruhle distinguished between sets of primary negative and primary positive features, each specifiable descriptively.

Thus, issues connected with theories of ‘negative’ and ‘positive’ abnormalities have been hotly debated since at least the time of Griesinger. A more recent attempt to examine the relationships between symptoms in long-term schizophrenia used a profile of four measures:

1 flatness of affect;
2 poverty of quantity and/or content of speech;
3 incoherence of speech; and
4 specific   types   of   coherently   expressed   delusions   and hallucinations.

Affective flattening was particularly associated with poverty of speech,  less so with incoherence and least with coherently expressed delusions. There was no evidence that the three types of speech abnormality were mutually exclusive categories (Wing 1961).

In a study comparing three hospitals with different social environments, poverty of content and quantity of speech were classified together with social withdrawal, flat affect, slowness, underactivity and low motivation as a ‘negative’  syndrome.

Incoherence of speech was included with delusions, hallucinations,  overactivity and socially embarrassing behaviour as a ‘positive’ syndrome (Wing & Brown 1961).

Crow (1985) gave added point to the descriptive separation by suggesting that different neural mechanisms might underlie the two syndromes, which he designated types I and II. Whether there are two, three or more syndromes has continued to be strongly debated, but now with fresh impetus to validate such clinical constructions by demonstrating biological differences.

Crow has subsequently suggested that the ‘first-rank symptoms’ provide clues to the process of separation of the two hemispheres of the brain ‘that is the species-defining characteristic of the brain of Homo Sapiens’ (Crow 1998).