There's a name of a psychological condition/behavior/phenomenon to describe the fact that a small increase in the difficulty of a task will prevent a person from doing the task at all. It stems from psychology and behavioral analysis, and it's often referred to by experimenters. It has implications in Computer Science with regards to users and the amount of effort required to complete a task in a program.
I can't recall what it is, and I'm having no luck with DDG.
I believe its 2 or 3 words together, and when I last read about it, it was on Wikipedia; I just can't recall its name. It's a specific name of a thing. I believe I've also seen it referenced in the SE communities on various meta.SE's.
Some scientists running an experiment would take note of how test subjects would choose between a set of things. If one of the things was slightly more difficult to obtain, often that slight increase in difficulty would be sufficient to prevent the test subjects from choosing that thing, and would instead choose the less difficult thing.
More concrete example
In more concrete terms, if the test subjects were supposed to pick up cards, then most test subjects would pick up cards off of the table because bending down to the floor would be slightly more difficult.