[Functions are available on the surface of the problem is the perception, essentially implies that the derivation of the problem: the irrationality of inductive reasoning. Perhaps because of this, it makes little children can easily produce many incredible ideas, while adults but this often baffling, puzzling, because their study, they assume that probably stems from inductive / deductive science of now! ]
Functional availability is perceived in the field of a new concept, the availability of psychological significance (affordance) that human perception of things is to provide the content may behave rather than the nature of things, and this behavior might provide things It is called availability. In simple terms, we can be functional availability of roughly understood as a possible meanings of things, it describes the process of environmental attributes and ontogenetic connections. American psychologist James Gibson (James Jerome Gibson) in 1977 first proposed the concept of functions are available. Gibson believes that availability is independent from the attributes of the human body, but is closely related to the ability of each person. In 1998, the cognitive scientist Donald Norman (Donald Arthur Norman) the concept of availability is applied to the field of human-computer interaction, compared to Gibson, Norman more emphasis may be perceived availability of (perceived under certain situations affordance) meaning, it is not only about the actual ability of individuals, will be influenced by psychology.
事物的属性往往是很丰富的，其中就有功能可供性。例如钥匙，就具有两类基本的功能可供性：权力上的可供性和物理属性带来的可供性。权力上的可供性是指钥匙可以打开和锁上我们的房间，这个可供性来源于钥匙和锁的匹配。物理属性带来的可供性指钥匙的形状、重量等物理属性带来的可供性，比如我们会将钥匙作为锯齿刀使用来划开包裹，会预先称好钥匙的重量以便判断电子称是否缺斤短两。而事物的何种属性会被我们知觉成可供性则与物理能力密切相关。这说明，事物的可供性，与人有着紧密的关系。布朗大学威廉姆·沃伦（William H. Warren）在1984年的研究中为解释这一点提供了一个经典例子：爬楼梯[1]。同样高度的楼梯，对于成年人来说，楼梯有着供其爬上去的功能可供性；然而，对于只会在地上爬的婴儿来说，这种功能可供性并不存在。相类似的，对于一个无法将钥匙插入钥匙孔中的婴儿来说，钥匙并不具备开锁的功能。而个体的目标、期望、计划、价值观等心理属性也会影响到我们对可供性的知觉。只有当我们需要拆包裹的时候，我们才会将钥匙作为锯齿刀来使用；同样的，假如市场中不存在缺斤短两，没有什么人会意识到可以用钥匙的重量来衡量电子秤。在一些更极端的情况下，我们可能仅仅知觉到事物的一个可供性，这个可供性往往是最常用的并且是被设计者预设的可供性，这时候就会发生我们心理学上所说的“功能固着”[2]。比如对一些没有开包裹的经验的人来讲，可能他们就难以想到可以将钥匙当小刀用而只能对着包裹干着急。
[1]Warren, W. H. (1984). Perceiving affordances: Visual guidance of stair climbing. Journal of Experimental Psychology: Human Perception and Performance, 10, 683–703.
[2] Ye, L., Cardwell, W., & Mark, L. S. (2009). Perceiving multiple affordances for objects. Ecological Psychology, 21 , 185-217.