... this study is rubbish. (a vibe I am sensing you all agree with)
As a biologist who has done studies, the pool was too small. The hypothesis was far too open.
Of COURSE the population all experiences intrusive thoughts. That is common knowledge among those with OCD. Many people without the disorder part of OCD speak of intrusive thinking. This is a natural battle within the human brain.
This would be like asking 50 able-NT people; "Do you sometimes feel scared being alone?" of course, the overwhelming answer would be "yes". This does not at all equate passing natural anxiety with an anxiety disorder.
That being said, this study also buys into the stigmatization of mental illness by trivializing it. Quote, “People with OCD and related problems are very much like everyone else.”. This is a tactic used by able people (meaning they are neurotypical, non-disabled). It is a way to trivialize a sometimes life consuming illness to lessen the severity of a mental illness. I have seen OCD literally (yes, literally) take a life. There is no comparison here between a random intrusive thought and a disorder.
That is why there is a difference between an Obsession Compulsion and Obsessive Compulsive DISORDER. Discorded thinking is not a normal occurrence. When thoughts such as "Did I lock the door?" turn into you checking your doors, 12 times, in a certain rotation at 9pm before bed and starting over if you messed up is disordered. Not just simply "thinking".
A person with OCD has different regions of the mind being active in different regions. As you all know.
Now, a person with passing obsessive thoughts will have the same regions "light up" (the frontal lobe). A major part of OCD is frontal lobe dysfunction. Which Gus pointed out, is usually handed down through genetics. Having dysfunction in the frontal lobe leads to attention difficulties, cognitive difficulties, and aids in spontaneous behavior (acting on compulsions).
The reason us people with OCD cannot process a compulsive thought like abled NT people is because we have a disorder, and from that disorder, we act. We don't have the choice to ignore an urge. Usually, we are brought into a panic thanks to Fight or Flight.
Assuming that a human with a DISORDER can just simply figure out how to apply these dysfunctional thoughts is an ableist, lame assumption.
TL;DR; if you're going to do a study, make sure your pool is bigger than 777 of mostly university students that aren't on disability/SSI/facing mental health treatment.