In my last brief comment, I tried to outline a basic concept about scientific research. I talked about skepticism: a fine virtue, that can withhold us from making too ambitious inferences from results, inferences that may in the end be grounded in our everyday experiences throughout our lives.
In many cases, in daily life it is not dangerous to draw a quick conclusion from observations, and later on to correct that conclusion if necessary. We can’t assess each state of events in all minutiae, because we wouldn’t be able to go on at all. Observing, concluding, taking in new information, and making corrections in our opinions and convictions is what happens all of the time. These activities are also charactistics of the scientific process, but pure and stern skepticism is a condition sine qua non in science. That is why I highlighted this in the previous post.
And now: back to the three possibilities that are there in the relationship between changes in the brain and symptoms of OCD. To recap: the symptoms may be the effects of these changes, the changes may be the effects of OCD symptoms, or there is a third and unknown variable that causes both the symptoms and the changes.
How can we get to know more about that relationship?
Suppose that we would be able to manipulate the brain of a patient with OCD to our heart’s content. Furthermore, we would have seen in some scanning technique that in a patient, in certain brain structures there is a suspiciously high level of some natural substance present, i.e. some stuff that we all have, but the patient simply has more of that in a couple of areas.
We write down a hypothesis, a conjecture about how that substance, which we call: ‘X’, may be related to the occurrence of a certain OCD symptom, e.g. washing hands in excess. The hypothesis then may be: the higher a specific regional brain concentration of substance X is, the more severe the handwashing compulsion of a patient with OCD is.
And here is the essence: if we can manipulate, we can determine the nature of the relationship between locally specified contents of substance X and severity of the handwashing compulsion (as, for instance, expressed in minutes needed to get a feeling of having cleaned the hands properly enough).
In our fictitious situation, we have as much substance X as we need, present in nice sterile tiny bottles. We prepare a range of different dilutions of X, in a physiologically convenient solution. And we do have at our disposal: ten healthy persons who are willing to undergo a brain injection with substance X (don’t mind how such a procedure can be performed in practice – it is a thought experiment). We are able to inject X into the precise areas in which our patient with handwashing compulsions had suspiciously high contents of X.
We divide the ten persons into five groups of two – and we have taken precautions that the ten subjects are a homogeneous lot, which means: same gender, about the same age, medication-free. The first group of two, we inject with the solution we diluted substance X with, but in this case, we administer the solution only. The other four groups of two we give the substance X solution each, but in increasing concentrations of X, e.g. we double the content of X with each group.
Then, we follow the ten persons closely in a clinical setting, for one month.
At this point, I must concede that there are a myriad practical objections to be made about this experimental design. Don’t worry. Only pay attention to the broad context, not the details, and not the incompleteness and the pitfalls.
The outcome of the experiment may be: the two people who got only the physiological stock solution without X don’t show any changes in hygienic behaviour. The two with the lowest dose of X don’t either. But the two people with double the lowest dose need approximately 1.5 times as long for a handwash than they did before (they themselves barely notice this, but our registration apparatus, a clock and a water meter, surely does). The two who in turn got four times the lowest dose need 2.2 times as long. And the group of two with the highest dose of X need 3.3 times as long to wash.
This is interesting. Although the lowest dose of X may be said to be subliminal, it seems to be below a treshold where X starts to affect washing behaviour, a higher application of X can be seen to induce a longer duration of the time necessary to wash one’s hands. Moreover, it looks like a doubling of the dose of X increases the washing time with a factor of about 1.5.
What did we learn in this little, rough, and yet interesting experiment?
1. Injection with only the physiological stock solution has no effect. This means that the whole procedure of treating a subject, handling him/her, injecting, and so on, as well as keeping him/her in the clinical context for the same time as the other people, does not affect handwashing time.
2. Apparently there is a threshold, a minimum concentration, below which substance X does not alter the time needed for handwashing, even if this may be added to the natural content of X already present in the relevant brain areas.
3. Substance X, given in certain concentrations from outside, is able to induce an increase in handwashing time.
4. Also, there seems to be some quantitative relationship between the dose (concentration) of X administered, and the washing time required by the subjects, to get a certain feeling of satisfaction, of being washed properly. It is no random effect.
OK, that is the entry for today. Perhaps my readers are willing to accept this challenge: try to shoot as many holes in this story of experimental design, strange substances, Frankensteinian hubris, water-wasting and germ-fearing human guinea pigs, and brain injections as you can. Scientific knowledge is no prerequisite.