This chapter is from the book
This chapter is from the book
This chapter is from the book
9.2 Memory Load
Callers cannot process large amounts of new information at one time and will not remember new information if it is not immediately useful to them. There are a number of techniques for creating menus, wording prompts, and providing instruction that help minimize the load on a caller's memory.
9.2.1 Menu Size
In an influential article titled "The Magical Number Seven, Plus or Minus Two," Miller (1956) described a pattern of human short-term memory in which people can store seven, plus or minus two, items. Often, designers use this as a guideline for the number of items to put in lists, menus, and so on. However, listening to sentences over the phone while trying to extract and remember information from these sentences is much more taxing than the tasks Miller used in the lab. The caller's task is more akin to the listening task in which subjects are asked to listen to a series of sentences and remember the last word of each sentence (Daneman and Carpenter 1980). In experiments using this completely auditory approach in which sentence comprehension is also taking place, people can remember only about three items on average.
Other research on human memory has shown that people naturally cluster items in threes and that recall is best when information is divided into groups of three or four items (Broadbent 1975; Wickelgren 1964). Taken together, the research results suggest that the caller's memory load should be kept quite small. A reasonable guideline is to limit menus to three or four items. Both Gardner-Bonneau (1992) and Schumacher, Hardzinski, and Schwarz (1995) make the same recommendation of four or fewer items in a menu.
9.2.2 Recency
When you write prompts, if callers are told specific words to use in response, make that the last thing they hear. For example, "To hear the list again, say, 'Repeat list'" is better than, "Say, 'Repeat list' to hear the list again." It taxes callers' memory less if the item they need to remember is the last thing they hear. This effect is often referred to as the recency effect. This ordering of function and then action in prompt wording has been adopted from standards of touchtone systems (Balentine 1999).
In addition to the recency effect, there are linguistic reasons to structure spoken sentences with the information of importance at the end. These are covered in Chapter 10.
9.2.3 Instruction
Applications that have many features and capabilities, especially those that will be used repeatedly by the same callers, often include instructional modes as part of the interactive application. Instruction sheets sent through the mail, or reminder cards with lists of commands, are not very effective. Most users do not read the instructions before attempting to use the system. Thus, applications need to be self-explanatory. It should be possible for an inexperienced user to get all needed help while using the service. We discuss two approaches here.
Tutorials
Some systems offer online tutorials, demos, or a combination of both. The option of hearing a tutorial is typically offered the first time a user calls the system. This approach is used mainly in subscription services or services that expect a lot of repeat use (for example, personal agents, banking, or brokerage account access). A tutorial consists of step-by-step instructions for using certain features of the system. A demo consists of a recorded interaction between a simulated caller and the system. The system voice speaks the prompts that are played during real system use.
Tutorials that present a demo of a user interacting with the system (CCIR-4 1999) and interactive tutorials (Kamm, Litman, and Walker 1998) have been shown to be effective instructional tools for new users. However, if too much information is provided or if the information is only described (rather than presented in an interactive mode), users have a hard time digesting it (Balogh, LeDuc, and Cohen 2001). There are two rules of thumb about tutorials:
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Teach only a very small number of concepts.
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Make it interactive. Have the caller actually perform the action.
Just-in-Time Instruction
When you need to describe a large amount of functionality, there are drawbacks to relying solely on a tutorial or demo. First, a caller will have difficulty following a lengthy description of diverse functionality. Second, if a feature is not exercised immediately, it is likely to be forgotten. In general, callers will not have the patience to listen to a lengthy description, especially if it is not helping meet their immediate needs.
The notion of just-in-time instruction can address these two limitations of tutorials (Cohen 2000). The basic idea is to provide only the instruction relevant to the task immediately at hand, just before the caller needs to perform the task. The amount of new information introduced at that point is small, and it is exercised immediately.
For example, consider a personal agent application with a rich set of capabilities. Rather than hear a detailed tutorial the first time they use the system, callers are instructed about particular capabilities the first time they access them. For example, the first time callers ask for traffic information they might get the following message:
You can get up-to-the-minute traffic reports for the major roadways in any city simply by saying the city name. You can also save time by saying the name of the road or highway and the city name. For example, you can say, "Highway 101 in San Francisco."
Just-in-time instruction can be offered the first time a caller exercises a particular capability. Additionally, you can offer instruction if a caller is having problems using the system, such as frequent rejects, timeouts, misrecognitions, and so on. If the caller is not making optimal use of system features (for example, not using shortcuts or not taking advantage of the richness of a grammar to efficiently input data), you can offer instruction.
The next two examples compare two approaches to instruction. In (2), first-time callers are offered a tutorial. The tutorial is lengthy and covers a large amount of information. It is doubtful that a caller will retain very much of what is covered, especially in future calls to the system. In (3), the application uses just-in-time instruction. The same material is covered (this example shows only the instruction on quotes and watch lists). However, it is offered in small pieces, at the time when that information is relevant and useful to the caller's current activity.
Note
(2)
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SYSTEM: |
Welcome to Princeton Brokerage. I can help you get quotes, set up a watch list, trade equities or options, and access your account information. To get a quote, simply say the name of the company. To set up a watch list, say, "Set up watch list," and then you will be asked for each company you want to put in your list. After you set up a watch list, you can get quotes for all of the companies on your list simply by saying, "Watch list." To make additions or deletions, say, "Edit watch list." To make a trade, say, "Buy" or "Sell," followed by the name of the company you want to trade, the number of shares, and the price. For example, you can say, "Buy a hundred shares of Intel at eighty-two," or "Sell fifty shares of Apple at the market." To trade options, say, "Options." To access your account information, say, "Account information." You will then be able to ask for your cash position, your holdings on any particular company, or a summary of all of your holdings. |
Note
(3)
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SYSTEM: |
Welcome to Princeton Brokerage. I can help you get quotes, set up a watch list, trade equities and options, and access your account information. What would you like to do? |
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CALLER: |
I'd like a quote. |
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SYSTEM: |
To get a quote, just say the name of the stock, mutual fund, or index name. |
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CALLER: |
IBM. |
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SYSTEM: |
International Business Machines is selling at eighty two, up one point three six. |
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CALLER: |
Cisco. |
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SYSTEM: |
Cisco is selling at seventeen point two five, up point one seven. |
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CALLER: |
I wanna set up a watch list. |
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SYSTEM: |
Sure, watch list. But first, let me tell you a bit about how it works. I'm going to help you put some companies on your list. In the future, you can get quotes on your companies simply by saying, "Watch list." Now, what's the first company to add to your watch list? |
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CALLER: |
Cisco. |
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SYSTEM: |
What's the next company name? Or, you can say. "Finished." |
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CALLER: |
IBM. |
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SYSTEM: |
Tell me the next company name, or say, "Finished." |
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CALLER: |
Intel. |
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SYSTEM: |
Next one? |
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CALLER: |
America Online. |
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SYSTEM: |
Next? |
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CALLER: |
<pause> |
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SYSTEM: |
Sorry, what's the next company name? <pause> Or just say, "Finished." |
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CALLER: |
I'm finished. |
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SYSTEM: |
Okay! Now whenever you want to get quotes for the companies on your watch list, just say, "Watch list." And to add or delete a company, say, "Edit my watch list." Now, what would you like to do next? |