Learning Barriers

    Six Learning Barriers in End-User Programming Systems http://www.cs.cmu.edu/~ajko/LearningBarriers.pdf

    学习在传统上被认为是人类特有的活动, 怎样降低学习的难度一直是理论上非常令人迷惑的问题, 同时它也是人类所面临的最大的实际困难之一. 在软件的世界中, 关于学习的研究也是一个非常重要的领域, 例如所谓的可用性(usability)和用户友好设计,其核心问题就是如何降低用户学习的难度. 我们目前的了解多半是一些经验的总结,例如Pane所总结的,
    . Use signaling to highlight important information.
    . Support incremental testing and feedback.
    . Choose an appropriate computational metaphor.
    . Help detect, diagnose, and recover from errors.
    . Provide guiding knowledge through online help.
    . Support recognition rather than recall.

    Andrew J. Ko等人作了更加严谨一些的研究, 试图对Learning Barriers作出一个基本的分类(classification),

1. Design barriers: I don't know what I want the computer to do, 需要mapping a desired program behavior to an
abstract description of a solution.
2. Selection barriers: I　think I know what I want the computer to do, but I don't know what to use, 需要mapping a behavior to appropriate search terms for use in help or web search engines, and interpreting the relevance of the results.
3. Coordination barriers : I think I know what things to use, but I don't know how to make them work together, 需要mapping a desired behavior to a computational pattern that obeys “invisible rules."
4. Use barriers: I think I know what to use, but I don't know how to use it, 需要mapping a desired behavior to a
programming interface’s available parameters.
5. Understatnding barriers: I thougtht I knew how to use this, but it didn't do what I expected, 需要interpreting the external behavior of a program to determine what it accomplished at runtime
6. Information barriers: I think I know why it didn't do what I expected, but I don't know how to check,需要mapping a hypothesis about a
program to the environment’s available tools, and interpreting the tool’s feedback.

    其中design, coordination和use的障碍体现了所谓的gulf of execution(the difference between users' intensions and the available actions), understanding的障碍则体现了所谓的gulf of evaluation(the effort of deciding if expectation have been met), 而selection和information的障碍则同时体现了gulf of execution和gulf of evaluation.
    
    关于以上分类的一件有趣的事情是它们之间的相互关系, 经常出现的情况是我们通过一些不正确的假定(invalid assumption)暂时克服了当前的困难,但是很快又遇上了其他不可克服的困难. 例如design barrier经常导向seletion barrier, 而coordination barrier和use barrier经常导向understanding barrier.

    对于如何克服这些学习上的障碍, Andrew J.Ko等人通过Factory的隐喻,提出了一些具体的建议, 但是实用意义不是很大.