Experience Once we have evaluated an idea and come to certain conclusions, it is much harder to go back and reevaluate the same idea. Sometimes having very bad experiences can especially curtail our willingness to learn.Some [real] examples:
A person tries object-oriented programming. However, he still uses the procedural paradigm. As a consequence, he finds that encapsulation gets in the way, etc., and that it's much faster to do it the procedural way. Trying to get this person to reevaluate OOP was like pulling teeth. He thought he had already tried OOP.
A person learns a particular style of MartialArts? and then discovers that to learn a new one he/she has to unlearn all that ClassicalConditioning (AKA reflexes) to learn a new one. Learning programming skills can be similar enough - reflexive styles can be hard to unlearn.
please add your own
Fear hindering us from trying newer, riskier ideas and staying with tried-and-true "safe" ideas.
Force by people telling us that we must learn, especially if in doing so they tell us that what we have long believed is wrong.
Laziness it takes more effort to learn something new than to just keep using your already-learned skills.
Time-constraints can blind you to the usefulness of learning a new/better tool. This is typified by the WoodsmanParable.
Physical effects you wont learn much if you are sleepy, or distracted by some other stimulus.
Emotional effects just been dumped? you probably aren't in the right mood to learn.