Passion or Perseveration?

"Building on your child's passions" sounds like a wonderful idea.  Why not teach a train-loving child using books about trains, train-related math, history of trains, drawing trains, train music, and so forth?  Why not visit train museums, take rides on trains, practice social skills in train stations?

All of these ideas are terrific - provided your child's interest in trains (or legos or Pokeman or football stats or anything else) is truly a passion and not simply a perseveration.

What's the difference?

A person with a passion is interested in their subject.  They want to know all there is to know about, say, baseball or astronomy or legos or Manga.  A person who is passionate about trains may specialize in collecting N-gauge historic engines - but that same person will likely want to visit a local garden layout...  experience a ride on narrow gauge railway...  take in a train museum...  explore Grand Central Station.  The passion is a sort of portal into a whole world of possibilities related to the topic of interest.

A person with a perseveration simply wants to have the same train-related experience over and over again.  The interest is not in trains, but in repetition and familiarity.  Thus, a child with a Thomas the Tank Engine perseveration may be willing go to a train museum where Thomas will appear, but he's there for just one reason: Thomas.  He is unlikely to engage with the museum or the other trains, and even less likely to engage with the people at the museum.  In fact, he may have a very tough time indeed waiting for his turn to ride on Thomas - and an even tougher time leaving the ride.

Is it a good idea to support a perseverative interest?

The answer to that question is very personal.  From my own experience, I can say that supporting a perseverative interest in a limited fashion has been helpful - because even limited play is better than no play, and even limited exploration of the wide world is better than none. 

And I have found that, over time, perseverative interests can and do expand.  For example, where once Tom was interested only in collecting, piling and fingering legos, today he builds entire lego world and creates elaborate lego-based stories.  He's made his own purchases in lego stores, used his own library card to borrow lego books, and has begun to collaborate on lego creations with other kids.

On the other hand, I've heard from parents and therapists who feel that perseverations are simply distracting - and serve no really meaningful purpose.  And many people have found it best to set aside the perseverative object or topic for at least some period of time.

What's your experience with passions and perseverations?