User Problems: Toasting Bread with Toaster 1 and Toaster 2

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Problem 3 of the third highest frequency (2 of 7 participants) was that of participants not being able to see the plug and switch at the mains due to low contrast (white on white). This caused problems for the participants with visual capability loss, highlighting the effect of environmental conditions on product usage. Other problems such as problems 8, 9, 10, 11 and 12 were caused by lack of contrast, adequate size or environmental conditions making visual tasks difficult. Participant 3 with relatively low hand function had problems with the rotary control, though other users experienced no difficulty with manipulating the control.

Participant 3 also had problems with reaching the plug and switch at the mains given that she was a wheelchair user (problems 4 and 5). Problems 6 and 7 were caused by environmental conditions such as the smoothness of the kitchen counter surface and the ambient lighting conditions.

In general, participants encountered problems based on the type of capability loss experienced. For example participants 5, 6 and 7 with visual capability loss encountered problems with visual tasks such as reading, and environmental problems such as glare.

Interestingly, these three participants checked to see whether the toaster was on at the mains before trying to operate the toaster and thus avoiding problem 2. This could be attributed to a learned behavior of people with visual capability loss, as they might not be able to easily detect some product state indicators due to poor vision. To compensate for this, they would make sure to check the mains power for a device before starting a task with a product.

In the case of participant 5 with visual capability loss, a problem with the tactile feel of the heating control was encountered. This participant was unable to see the heating control clearly and therefore relied on tactile feedback to operate it. Because the control was smooth, he experienced difficulty in turning it to the desired setting. The control was also a continuous control, and there were not discrete stops or ‘clicks’ that could assist in setting it at the right value. This serves as an example of one sensory modality being used to compensate for a lack of another, representing one form of a coping strategy.

In other cases, for example with participant 1, though motor capability difficulties in daily life were reported, there were no motor difficulties encountered in the product task. Therefore it can be concluded that the participant possessed sufficient motor capability to perform all motor tasks required of the product. Without knowing the specific level of capability loss of the user and the specific capability demand of the product, it is not possible to determine if a user can or cannot perform a task. This implies that knowing whether people experience capability difficulties in daily life is not enough to make judgments about the difficulty experienced in product usage.

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Table 6-4 lists the main problems encountered by participants when performing the task of making toast with toaster 2. Problem 1 resulted in confusion over the function of the small sliders on toaster (used for ejecting the toast out of the slots). Problems 2, 3, 6 and 7 involved difficulties in seeing and reading interface features. Problems 4, 5 and 7 resulted from misunderstandings about the mapping of interface features to each other, and also in understanding what certain features and symbols meant.

Table 6-4 Problems encountered by participants using toaster 2 Participants

Difficulties with 1 2 3 4 5 6 7 Freq

Vision 4

Hearing 2

Remembering what you were doing (your memory) 1

Walking 2

Lifting objects 3

Twisting and turning dials and knobs 2

Grasping, pulling or pushing 2

Problems Encountered 1 2 3 4 5 6 7 Freq

1. Difficulty encountered in understanding the function of the small levers (used to eject toast)

3 2. Difficulty encountered in reading the LCD display 2 3. Difficulty encountered in reading text on buttons 2 4. Erroneously placed toast in two middle slots

rather than using a pair of slots on the ends

1

5. Found symbols on buttons confusing 1

6. Difficulty encountered in reading the label on the slider

1

7. Unsure what buttons do 1

8. Light reflection caused glare problems 1

The usage of toaster 2 resulted in a smaller number of problems overall than toaster 1. This was due to certain visual problems being avoided with toaster 2. For example, since the plug and cord were black on toaster 2, there was high contrast against the white mains fixture. The toaster was also larger and heavier, so it did not slide on the kitchen counter surface. All interface features were to the front of the toaster for easy access, and it indicated the ‘ON’

state readily as the LCD display came on once there was power available. However, due to the increased number of interface features on toaster 2 such as buttons with icons and a screen, more cognitive problems were introduced compared to toaster 1.

As with the case of toaster 1, participants encountered problems based on the type of

capability loss experienced. For example participants 5, 6 and 7 with visual capability loss all experienced different types of visual problems. Participants 1, 3 and 4 with motor capability

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problems in daily life did not experience any significant motor problems with toaster 2, implying that their motor capability was above that required to use the toaster. Participant 4 who reported problems with memory in daily life encountered the most problems with understanding the features and functions of the toaster.