We judge our past experiences almost entirely by their peaks (pleasant or unpleasant) and how they ended.
A group of doctors were considering how to make colonoscopies less painful and uncomfortable but reached the conclusion that, while it was not actually possible to make it less uncomfortable because of the nature of the procedure and tools they needed to employ, it was still possible to improve the experience.
They found that when the procedure was done as quickly as possible, even though the patients had to endure the procedure for less time, their final experience was still one of intense pain and discomfort. However, if once the important part of the procedure was over they took time to withdraw their tools as delicately and sensitively as possible over an extended period the final experience was not so bad. Patients of the second version, questioned immediately afterwards, mostly described the experience in less terms of discomfort than patients of the first procedure despite the fact that, other than the way they ended, both procedures were identical.
The patients in both cases were only remembering the comparative difference between the peak of the experience and its end – in the first version both the peak and the end were intensely uncomfortable and painful. In the second version the peak was just as uncomfortable as the first but the end experience was more bearable. The softer ending tempered the memory of the peak of the experience.
An arduous process that ends abruptly will be remembered as being difficult or bad whereas the same process that tails off into simple tasks will be remembered as being easy and, comparatively, not so bad.
If we need to make our users go through some difficult process such as a sign-in or registration we should ensure that we try to surprise and delight them as they journey towards the end of it. This could take the form of anything from allowing them to make choices throughout the journey to give them a sense of control or simply employing more friendly language. It may even be worth extending the process by one or two steps to include the friendly touches just as long as the last few steps are the most simple and entertaining – those are the steps that they will remember more.