Expectations and assumptions - The human brain works by making assumptions based on experiences and associated deductions.
If a user action or input is required for a product and the user doesn't have an obvious relationship with some previous function, then the human brain moves into deducing what needs to be done.
If the deduction process doesn't work due to complexity, the user will get frustrated and then give up. Behaviouralist Dr. Daniel Kahneman, the Nobel Prize winning behavioural economist, has explained this in great depth in his great book, "Slow Thinking, Fast Thinking'. This is also echoed by UX pioneer Jakob Nielson "People give up if the item is not found where it's expected to be."
What we want to do is put ourselves in the shoes of potential users to anticipate their expectations and assumptions. A good example of this assumption can be seen in my car. I drive a Volvo C30 and in the Australian model (the driver is on the right-hand side); the ignition is on the left-hand side of the steering wheel.
Whenever someone tries to drive my car, it takes them a good 60 seconds or so to find the ignition. The intention of the designer to create a clean-looking dashboard arrangement does not equal the users' assumptions and expectations. This little thing could put off more than a few customers because it may not feel right to them.
Malfunctions - Frustration can come from malfunctions of a product or service.
for example, a bug that causes a certain script to occur and results in a frozen screen. Frustration can also result from errors made by users due to misinterpretation, confusion, being under pressure, or simply failing to understand how to use something.
Don Norman the forefather of UX design, explained in his wonderful book, "The Design of Everyday Things', that if something goes wrong, it's easiest to blame it on human error. Even if it is human error that has caused a malfunction, the reality is that the human error has usually resulted from a complicated product or process that is beyond the average functioning of a person in a particular situation.
We need only to look at pilots trained to use complex instrumentation who make mistakes because, as Norman says, "We are human and likely to err."  Don Norman "The Design of Everyday Things" Basic Books New York: (2013)
Identifying any existing malfunctions and potential recurring human errors can provide designers with the opportunity to alter their design and thus, to prevent future frustrations.
It's human to err - We make slip-ups all the time.
Testing for potential slips before we build, and testing for actual slips as we build, gives us the rare opportunity to reduce financial slips later on that are the result of having to rectify customer frustrations and poor design.
To improve our customer experience we need to adopt a mindset that tests across a number of different areas. When testing, during pre-construction or when working with iterations, we should ask questions such as:
Useable - "How easy is it to use?'
Simple - "Is it simple to understand or is the user overwhelmed with decisions?'
Logical - "Is there a logical sequence, a place to start, or a way to turn it on or off?'
Intuitive - "Is it natural to use?' "Could a seven-year-old pick it up and know how to use it?'
Painless - "Are there any components that create frustrations?'
Fool-proof - "Does it prevent you doing stupid things with it?'
Accidental - "Does it prevent you from making a major mistake?'
Inventive and preventative versus corrective and re-inventive
It's cheaper to prevent mistakes than to correct mistakes. Good design, be it for a product, process or service takes UX on-board by being preventative and inventive at the same time.
Inventive - The inventiveness of UX and CX design is useful when looking at preferences. These include, for example, where we prefer to have things located, how we prefer to hold things and where we tend to shift our eyes. Understanding all of these key areas can help invent an innovative product that feels seamless and intuitive.
Eye tracking - This is a classic example of a tool that some UX designers use, to analyse where people's eyes are most likely to look when on a website page. Reading direction preferences change from culture to culture. Western cultures read left to right, some Asian cultures read top to bottom, and Middle Eastern countries read right to left. If you're looking at a new design for an online service, knowing these preferences and where the eyes go is important. It's even more important to know why the eyes go certain places.
UX designers investigate this by acting as behaviouralists and by asking quantitative and qualitative questions that determine the reason behind eye movements, most of which are unconsciously motivated and almost impossible to discover using other research methods.
Preventative - Suggesting constraints that will prevent unwanted mistakes or errors is extremely important. Some simple examples of this are: a knob that can only be turned one way or having a pop-up box that requires you to type the word DELETE before you delete a whole database.
If an accident is possible, UX designers look for constraints to help minimise its occurrence.
Re-inventive - After testing, observing and questioning users of a product or service, we need to work quickly to create a new iteration of the product that incorporates new modifications, to deal with prior complications and frustrations.
Time is of the essence, as each iteration slows eventual production. Whilst we need to be cognisant that we may be holding up the production line, if the frustrations we identify are not addressed, the whole project suffers. This is what drives UX designers to iterate quickly and swiftly, in conjunction with the original designer or with their own designers.
Corrective - There are times when we need to correct something that was already thought to be corrected, previously. Rather than point fingers in this situation, our job is to simply identify the assumptions and expectations of users, identify potential malfunctions and misinterpretations and come up with new solutions to correct the situation.