Back in the middle of the 20th century, when Claude Shannon introduced his信息theory不仅他彻底改变了信号处理的科学,而且他还深深影响了其他学科的队列,从计算机科学和人工智能开始,并以认知心理学结束。来自信息理论的一个想法是通信系统是由modules通过有限的容量通信连接channels

人体设备通信通道

该basic concept in information theory is the通讯系统。通信系统包括:

  1. modules: an information source and a destination.
  2. 一种communication channel从源将信息从源传输到目的地。

该communication channel has a certain容量that limits the amount of information that can be transmitted from source to destination. For instance, a network that connects 2 computers can be thought of as a communication system; the network bandwidth (which normally refers to the amount of data that can be transmitted between the 2 computers) is equivalent to the channel capacity. For example, if you have a 50 Mbps Internet connection, your computer can receive 50 million bits per second across the network (assuming everything is working at full speed) — that is the channel capacity.

While the clinical-sounding terminology describing these concepts may make them seem dated, nothing could be further from the truth. The idea of modules and channels is a powerful one and can and should be applied to the new art of mobile design.

当用户与技术(计算机或移动设备)交互时,它们形成具有两个模块(用户和设备)的通信系统和它们之间的通信信道。该频道的容量受到设备的组合特性和与其交互的组合特性。这些特征包括:

  • 用户的工作记忆
  • 该amount of attention that the user is able to devote to the communication
  • 该size of the device screen

We will discuss each of these characteristics separately and we will see how each of them influences mobile design.

But before doing so, we need to stress that, unlike for computers connected by a physical network, when we talk about communication capacity in this article, we're not talking about the number of bits per second a person receives, because we're not interested in raw data. Rather, we want to know how much信息the person has internalized from dealing with the数据on the screen.

用户的工作记忆限制了通信通道的容量

如果一个人听着讲座的人,他必须大多依靠他的记忆来记住发言者是指的,并将新信息连接到他的背景知识或其他想法,即发言者可能已经引用。该工作记忆听众的征税严重征税(至少如果他注意):他必须记住之前提出的部分信息,以了解稍后介绍的新概念。工作记忆是一个非常个性的变量;不同的人可能有不同的工作记忆尺寸。我们可以在我们的工作记忆中保持多大程度决定了理解的质量。良好的演讲者知道他们的观众,并节奏他们的演讲,以满足小而大的工作记忆能力。

When browsing the web, users keep information about their current goal in their working memory. For instance, they will carry information such as “I am trying to plan a vacation in France for my family during the month of July”. They also use their working memory to store contextual information about the site, about the current page, and about the site’s interface. (The concept of working memory is closely related to that ofcognitive load。因此,人体设备通信信道的容量自然受用户的工作存储器的限制。如果网站或应用程序询问用户学习过多的新信息(例如,由于呈现的内容太复杂或者是因为互动是唯一的或不寻常的),通常用户将达到他的工作内存不具有的僵局该信息不再是他需要去寻找它。有时,搜索可能很容易 - 例如,如果用户需要在那里,在同一页面上,在他的眼前。在其他情况下,用户可能需要远离当前页面(因此突起更高互动成本)找到解决他的僵局所必需的内容。

(For much more on the impact of human-memory characteristics and limitations on UX design, see our full-day course on该Human Mind and Usability。)

Screen Size Limits the Capacity of the Communication Channel

每次用户不了解网站上呈现的内容时,她都可以查看在她面前显示的其他信息。显然,屏幕的大小限制了一次可以看到多少信息,然后滚动向下或向上或向上导航到不同的页面之前。因此,在人体设备信息系统中,通信信道的容量由屏幕尺寸确定。(随着我们稍后会看到的,注意跨度和其他单独变量也可能影响信道容量。)屏幕尺寸越大,人和设备之间的通信信道的容量越大。一旦人们必须采取行动并导航到不同的视图(通过滚动页面或完全切换页面),用户将产生(1)交互成本;可能(2)额外的内存负载(无论是因为他们必须记住这个页面上的内容,也是因为他们必须记住他们在哪里可以去寻找所需的信息)。

较小的屏幕尺寸是主要原因mobile content is twice as difficult than desktop content: because the mobile screen is so much smaller, users must rely on their working memory to keep around information that exists on the page but is not visible in front of their eyes.

一种ttention Limits the Capacity of the Communication Channel

除屏幕尺寸外,影响通信信道容量的另一个变量是用户可以投入设备的注意力。更便携的设备,人们越可能使用它到处都很可能,并且在使用该设备时也要更有可能中断。具有便携式设备的注意力与桌面计算机非常不同。事实上,2011年在移动HCI中发表的一篇论文显示了average session duration on mobile was 72 seconds。虽然现在可能是几秒钟或多或少,但是移动网站或应用程序基本上略微超过一分钟,以帮助用户到达他们所需要的地方。(相比之下,平均值session size on the desktop is about twice as long- 2.5分钟。)

移动设计和通信通道的容量有限

Designing for different screen sizes needs to take into account the capacity of the communication channel. Designing for mobile is pretty much like passing a camel through the eye of a needle: it’s hard to do it through such a tiny channel. Different approaches to mobile design attempt to solve the problem in different ways, but they all need to be aware of the limited channel capacity.

Responsive design (in the most “purist” sense of the term, that insists that the identically same functionality and content will be available on all devices) solves the capacity problem by chopping up the site into cells on a fluid grid and rearranging those cells on the smaller screen in a way that takes into account the relative priorities of the cells. Basically, it delivers the same content piece by piece through a narrower communication channel. As a result, all the content is available on smaller screens. Remember, however, that the user inherently will have to work harder and keep more items in memory to get to a random piece of information on the site.

一些用户可能愿意花时间和努力,其他人会只是放弃(或由于中断而被迫放弃)如果他们在合理的时间后没有找到他们需要的东西。因为敏感的设计linearizes the content(通过降低内容网格的维度,从M行向n×m行按1列,在设计智能手机的极端情况下,它要求用户在达到任何特定之前顺序地通过内容一点信息。因此,技术facilitate direct access与反应是非常重要的设计:在做什么sure that the navigation is easily accessible and contains pointers to all chunks of information that may be potentially relevant to a user.

在桌面上的2×3电网上布置的响应网页可能会转换为智能手机上的1×6格。如果移动用户对块号4中的内容感兴趣,因此她需要通过块1-3顺序向下滚动以查看它。相比之下,在桌面(或更大的屏幕)上,块4中的内容通常会立即可见(无需滚动)。

(As an aside, the communication problem inherent in linearizing a web page is one of the main reasons for which盲人的用户比在使用网站的观点的用户慢:通过屏幕阅读器听到线性方式大声读出的信息,而不是在屏幕上的相同信息的视觉扫描的效率较低。对于盲人的用户来说,听觉渠道是他们所拥有的,设计人员可以采用像这样的伎俩Skip navigationlinksto expedite use despite the limitations of sound. For sighted users, it behooves us to expedite their use even more by exploiting the strengths of vision.)

Websites that are specifically designed for mobile start from a different assumption. They do take into account the limited channel capacity and make assumptions about what the users may be interested in. They deliver to the channel: they presume that, since content that’s buried too deeply into a site or app will be hard to find anyway and unlikely to be used, they’d better not pay the price of information overload or long load times; hence they leave out functionality and information that is deemed mobile unworthy.

Mobile sites bet on knowing what’s important to the mobile user and trim the content and functionality to fit the narrow mobile channel. The challenge is: how well can designers guess what the user needs will be on mobile? Is it better to have information out there, even if buried in a long page, under the assumption that those who need that information will be motivated enough to find it despite the higher interaction cost? This is a call that must be made from case to case.

应用程序怎么样?应用程序通常放弃通过针的眼睛通过骆驼;他们认为,在快速移动世界中,用户不会因骆驼而烦恼。移动应用程序(至少那些who don’t simply enclose a mobile site in a native app) invent a new creature altogether, better suited to the demands of the device. They usually are built around a few tasks that they often support creatively and fully.

简单的连续性

When designing for mobile we often recommend simplicity. Simplicity means taking into account the capacity of the communication channel. A simple app or website is tailored to the channel capacity and does not make users work more than necessary to attain their goal. It takes into account:

  • 用户限制(使用设备时的工作内存大小和注意),以及
  • the device limitations (the screen size)

设计师有时误解了简单性的概念 - 他们将其视为静态和独立于设备。我们看到平板电脑应用程序,这些应用程序很闪过手机应用程序,我们看到了这样的系统Windows 8.;试图在两张平板电脑和桌面上安装一个设计。什么simple and appropriate在手机上可以只是愚蠢on a tablet or on a desktop.

当Windows 8首次出来时,今天的应用程序中有一点点文本的巨大图片忽略了桌面 - 人道的大量容量,并用太少的信息浪费了它。(较新版本的Windows8已重新设计以来以便提高渠道容量。)

Not taking advantage of the channel size is bad because it makes users work unnecessarily (that is, interact more) to get to content that could have fit a single screen span. To continue our accessibility analogy, it's as if we forced everybody to have low vision and only see very little at a time.

SmartWatches位于简单性连续的另一端。在屏幕中向1.5中显示桌面网站将是荒谬的:没有人能够滚动通过所有可用内容滚动。

我们在哪里领导?

很明显,我们正朝着普通设备填充的互联世界 - 从智能恒温器,智能手表和智能眼镜,智能手机,百搭,平板电脑,笔记本电脑,台式机,智能电视和智能桌面。我们需要一个统一的理论,用于设计屏幕尺寸的连续体。该理论不能将所有这些系统减少到单个分母;为SmartWatch设计设计与平板电脑的设计不同,并且为桌面设计的设计与设计不同。虽然许多原则可能是相同的,但它们在不同的设备上以不同方式应用。我们需要更多细微差别。信息处理方法考虑了用户和设备之间的通信信道的容量,并且可以提供用于缩放用户界面的开始点。

在我们的课堂上讨论了更多关于为不同设备设计的差异和相似之处扩展用户界面

参考

M. Bohmer, B. Hecht, J. Schoning, A. Kruger, G. Bauer. Falling asleep with Angry Birds, Facebook and Kindle — A large scale study on mobile application usage.Mobile HCI 2011