Why do people leave their dog poo bags anywhere and everywhere?

[Dean Resident]

Hi Everyone,

I am doing some research into the psychology of littering, and would like to hear views specifically about why people leave dog poo bags in the countryside.  On the face of it, it seems odd to go to effort of bagging the poop, but then deciding to leave it, often in plain sight.  This implies that an owner recognises the need to clean up after one's pet, but does not feel compelled to dispose of the bag complete with contents.. 

This is an un-scientific survey, but some reasons could be:
1. Expect someone else to pick it up (the council, national trust, woodland trust..)
2. Forgot to pick it up whilst on a circular walk
3. Have 'bio-degradable' bags (which don't actually degrade in the open countryside)
4. other reasons..
 
Would appreciate your views.