If you are a product manager, you probably spend a fair amount of time writing specifications for all the great new ideas that you want to see built into your product. There are hundreds, even thousands of questions that need to be considered during feature development. One thing I want to highlight in this post is to be careful with features that affect other parts of the system in non-obvious ways.
For example, the investment management firm, T. Rowe Price, has a feature that allows online users to make IRA conversions with their funds. I’ve been a long time user and the newly updated UI is extremely well done. The conversion wizard steps the user through the process in a clear way, but I noticed some fine print at the bottom of one of the steps:

What’s happening here is that the process of going through the IRA conversion feature will turn off another feature that the user had setup in the past – specifically, it turns off automatic transactions into the account you want to convert. This is what I call a “side-effect” requirement – doing one action causes a ripple effect across other parts of the system that are not immediately obvious. T. Rowe Price could have decided to allow the automatic transactions to continue, but I can see how this may have caused a different set of problems. I suspect the logic behind this decision went something like this – users that want to convert the IRA most likely don’t want to continue to contribute to it, so we’ll turn off automatic transactions by default and prevent any unnecessary funds from being withdrawn. There’s no clear cut answer, but the product manager had to make a decision on how to reconcile a potential problem.
Once the business rules are set, the question goes to the UX designer on how to notify the user of the side-effects, and this is the tricky part. Here, they’ve chosen to put a simple message that explains the situation. Another option would have been to slow down the user with a message prompt to force them to take a look. The message could also have required a confirmation (i.e. checkbox to continue) to make sure the user understood what was going to happen. My guess is that the implications of this side-effect were decided to be not-so-bad and a message would suffice.
It’s important to be aware of these intra-system interactions so that the user doesn’t get blindsided by not knowing why some things happened. Even as the product expert, it’s not difficult to forget a rule, especially ones that interact across disparate parts of a complex system. If the experts can forget, a normal user will almost always forget.
Some tips when you come across side-effect rules:
- Try to avoid them to begin with. There’s more art to this than science because it involves being creative about how to design the interactions between different parts. In my experience, I’ve found that you can usually design them away or find that they really aren’t necessary. It’s always better to avoid potential confusion but sometimes it’s unavoidable, so aim to minimize the impact.
- Consider the scale of the side-effect. Understanding the scope of the side-effect will help you determine how heavy-handed you need to be in UI.
- Document it. Rules should obviously be spec’ed out but adding notes about use-cases or justifications will help your team make informed design decisions about that feature in the future.