Much of my work as a scientist was theoretical in nature; but I published quite a few empirical (i.e. experimental and observational or statistical) papers as well.
One particular favourite of mine, and which seems to have been somewhat influential too, was done with a student called Florence Walston who was intercalating a bachelor of science degree into her medical studies, and who did the actual "leg-work" and analysis; and Richard Blennerhasset - a clinical psychiatrist, who provided access to the subjects studied.
I liked this paper because it was as clear an example of "Black Swan"-type - Karl Popper-esque - research as one is likely to find in medicine.
So, what do I mean by "Black Swan" in relation to science?
Well, to state the matter more "softly" than did Popper (who wrongly regarded it as logically definitive of "science"); the idea is that it is not possible to "prove" positively the "hypothesis" that "all Swans are White" by gathering observations of White Swans - no matter how many examples of White Swans that we discovered and counted...
But it may be possible to dis-prove negatively the "hypothesis" that "All Swans are White" - by finding even just a single example of a Black Swan.
In other words, if there is one Black Swan, then all Swans cannot be White*.
The asymmetry of this logic, the power of that single necessary observation, is recognized by using the definite article "the", in referring to The Black Swan whom we ought to be seeking.
In this research, we aimed to refute the theory that persecutory (also called "paranoid") delusions are caused by defective "theory of mind" (ToM) ability.
In other words that when someone falsely and firmly believed that he was being persecuted by some person or group of people; this was caused by a fault in his ability to infer the thought and intentions of those other.
The "hypothesis" was implicitly that all people with persecutory delusions, must exhibit defective "theory of mind ability.
All we needed to do was find a single clear and un-ambiguous example of a person with persecutory delusions but with normal ToM; and we had found our Black Swan and refuted the hypothesis.
So, to refute this theory, we sought-out examples of people who did have definite persecutory delusions, but did not have anything wrong with their "theory of mind" ability...
On the basis that if someone actually suffered persecutory delusions yet also displayed normal theory of mind functioning, then the delusions couldn't be caused by defective ToM.
“Theory of mind”, persecutory delusions and the somatic marker mechanism. Florence Walston, Richard C Blennerhasset, Bruce G Charlton. Cognitive Neuropsychiatry. 2000; 5: 161-174.
Introduction: Pure cases of persecutory delusions can be interpreted as “theory of mind delusions”; using a model that equates the theory of mind mechanism with the “somatic marker mechanism” as described by Damasio and colleagues. Three predictions were tested in a case study design: that pure cases of persecutory delusions could be found, that such cases would retain normal theory of mind reasoning abilities, and that delusions would be encapsulated to a specific group of persecutors with hostile intentions.
Method: The caseload of 17 psychiatrists and 4 community psychiatric nurses was surveyed for “pure cases” of persecutory delusions. Cases were excluded when there was evidence of other psychopathology, intellectual impairment, abnormal reasoning, “psychotic” features, or diagnostic syndromes. Selected cases were evaluated for the scope of their delusional beliefs and the nature of their social relationships using a detailed semistructured interview that was transcribed verbatim, and putative “theory of mind tests” as devised by Corcoran and Frith.
Results: Thirty-four potential cases were referred among which four pure cases of encapsulated persecutory delusions were eligible for the study. All were men, aged between 32 and 43. Apart from their persecutory delusions, cases were free from other detectable pathology in their reasoning processes, affect, or social interactions - and scored highly on the putative “theory of mind tests”. Identified persecutors were males, and delusions involved false beliefs concerning the threat of violence from gangs of strangers.
Conclusions: Pure cases of severe but encapsulated persecutory delusions can be found, and such cases demonstrate intact theory of mind reasoning ability. The nature of persecutory delusions is understandable in terms of the somatic marker mechanism, and the content of delusions is consistent with the nature of hostile threats to men in the ancestral human environment.
In sum, Florence found, interviewed and tested not one but four "Black Swans" (actually five, but one withdrew consent to being included in the write-up); the Black Swans being men had such severe persecutory delusions as to have required admission to a psychiatric ward; yet who passed the Theory of Mind tests "with flying colours".
That is: five men with severe persecutory delusions who demonstrated no measurable (or indeed inter-personal, conversational) evidence of impairment in their ability to infer the motivations of other people.
In simple terms; outside of the specific subject of their severe delusion; these men thought and reasoned normally - so far as we could judge.
From which it seems reasonable to infer "negatively" that all persecutory delusions are not caused by defective theory of mind abilities -- although, of course, some persecutory delusions might nonetheless have this cause.
*Note. In practice, a single observation will very seldom have this power; usually argued on the basis that the Black Swan is either not-really Black, or else not-really a Swan.
