The obsessional process may be akin to the generation of antibodies by the immune system. Whether or not an antibody increases in concentration will depend upon the subsequent feedback. While antibodies have the function of protecting the body from invisible dangers within the body, obsessional thoughts are designed to protect the individual primarily from external dangers within the environment. It is suggested that both operate through a selectionist process - that is, the better fit antibody or thought survives. Some authors have suggested that a similar process, involving the selection of random and spontaneously generated thoughts, lies at the heart of all human thinking (Blackmore, 1999;Gazzaniga, 1992; Plotkin, 1994 & 1997).
Bickerton (1996) has proposed that there are two fundamental modes of thinking: on and off-line. On-line thinking is common to many complex organisms and involves mental activity designed to solve a problem directly faced by an individual. Off-line thinking involves mental activity aimed at solving problems that the organism may face at some time in the future. Bickerton contends that off-line thinking is language-based and, therefore, unique to the human species. Within this framework, obsessional thinking could be considered as a primitive variant of off-line thinking, albeit of a non-voluntary type. Although the idea that human thought is language based is not universally accepted ( Pinker, 1994), there may be grounds to suggest that obsessional phenomena could have been the evolutionary precursor to voluntary conscious thinking. This would raise the interesting question as to whether obsessions, as conceptualised in this paper, exist in other species. The main obstacle in studying such a system in non-humans is, of course, the inaccessibility of their subjective states and, at least at present, the question can only be investigated indirectly through determining if something akin to obsessions could be implicated in learning in other species.
First, we must take a moment to define independent and dependent variables. Simply put, an independent variable is the cause and the dependent variable is the effect. The independent variable can be changed whereas the dependent variable is what you're watching for change. For example: How does the amount of makeup one applies affect how clear their skin is? Here, the independent variable is the makeup and the dependent variable is the skin.
A simple hypothesis is a prediction of the relationship between two variables: the independent variable and the dependent variable.
Overweight adults who 1) value longevity and 2) seek happiness are more likely than other adults to 1) lose their excess weight and 2) feel a more regular sense of joy.
The present hypothesis is compatible with a range of other proposals and theories dealing with the proximate level of causation, i.e. genetic, neurochemical and environmental factors, in OCD. Psychological theories that emphasise an acquired environmental causation (e.g. Salkovskis, 1985) as well as findings pointing to a biological aetiology of OCD (Rosenberg & Keshavan, 1998) are both consistent with the present Darwinian formulation. Whereas the present hypothesis describes the adaptive function of a putative neurobiological system, addressing the question of 'why' it exists, it is compatible with theories that explain 'how' it works.
It is contended, therefore, that anxiety and panic are on-line emotional states, designed to generate risk avoidance behaviour as a direct response to the exposure to immediate (real or imagined) dangers, whereas the obsessional system is an off-line process primarily designed to generate harm avoidance behaviour in response to dangers that may be encountered at some time in the future.
Hence, the present hypothesis presents a novel formulation to explain the ultimate causation of OCD, thus attempting to integrate this condition into the now well-established field of evolutionary psychology and psychiatry. An important feature of the current hypothesis is the proposal of a putative mental module (IRSGS) that is charged with the generation of risk scenarios without voluntary intervention which, in turn, give rise to a range of risk prevention behaviours described as compulsions. This proposal uniquely contends that overactivity of the IRSGS will lead, in certain circumstances, to OCD or PTSD while underactivity of this module may be associated with APD or other manifestations of persistent high risk-taking behaviour. Furthermore, the current hypothesis clearly proposes that obsessional phenomena are examples of a mental adaptation that has evolved through a process of selection and that OCD is, therefore, the result of the malfunctioning or dysregulation of this system.
The phenomenological similarities between OCD and post-traumatic stress disorder (PTSD) have been noted by a number of authors (e.g. Lipinski & Pope, 1994). According to the proposed hypothesis, the frequency of obsessional thoughts would be expected to increase following traumatic or threatening situations, whether involving physical danger or distressing social situations. Such events should therefore activate the IRSGS by presenting the subject with a range of novel risk situations and provide a potential explanation for at least some of the clinical features of PTSD e.g. recurrent intrusive thoughts and images as well as recurrent dreams. Therefore, from an evolutionary perspective PTSD, could be considered as a pathological accentuation of an adaptive response that previously led to the modification of an individual’s behaviour and future risk reduction (i.e. learning). In addition to thoughts and images during the waking state, the IRSGS may also utilise dreams as a mechanism for risk avoidance, thus accounting for the increased frequency of vivid dreams and nightmares characteristic of PTSD. However, it is clear that these two disorders, ie. OCD and PTSD, also differ in some important respects. For example the absence of compulsive rituals in PTSD cannot be explained within the present hypothesis.
Thus, conceptualising obsessions as risk scenarios and compulsions as risk prevention routines will help to clarify the clinical observation that while obsessions increase anxiety, compulsive rituals reduce anxiety (at least temporarily) (Rachman & Shafran, 1998).
If obsessive-compulsive phenomena relate to risk scenarios to self and close kin, it should be possible to predict an increase in the frequency and intensity of risk scenarios and harm avoidance rituals at biologically critical times, e.g. following childbirth or around puberty . Current evidence supports the claim that pregnancy and childbirth are associated with significantly increased risk of OCD for women (Buttolph, Peets & Holland, 1998).
Epidemiological surveys of OCD have found a small preponderance of female subjects (Weissman, 1998). As females would be expected to engage less frequently than males in risk taking behaviour (Daly & Wilson, 1983; Browne, 1998) such a finding would be consistent with the present hypothesis. Also there is evidence that gender differences vary according to the age of onset of OCD with males showing a higher prevalence prepubertally and females more commonly affected post-pubertally (Penn, March & Leonard, 1997). It is possible that the increased risks that females were exposed to following puberty within the ancestral environment could have led to the increased activity of the IRSGS leading to the greater incidence of OCD.