Context
The following situation occurs when users initiate a process that requires an account to complete. They are prompted to log in.
In this particular scenario, the response should be quite straightforward; it should simply prompt the user to "Login." However, many apps redirect users to a "Create an Account" page instead (with a smaller-font option to log in if they already have an account). While some may argue that this approach is incorrect, my focus here is on a specific case that I find more intriguing: ambiguity and undetermined states.
At times, the prompt can be more ambiguous, such as "you need an account," or there may be subprocesses involved.
For instance, I recently found myself logged into an app, needing to add a payment method. Due to security concerns, the app required me to log in again but redirected me to a Signup form instead (with the typical smaller login text). This pattern is particularly prevalent in Blockchain and financial apps, where numerous security steps may require repeated logins, yet a signup option is presented first.
One explanation could be that security measures, such as clearing cookies or cache, might cause the system not to recognize an existing user. As a result, the system might perceive them as a new user, even if they had logged in just moments earlier.
And yes, sometimes this is merely a result of poor design. But then, what is the correct approach, and why?
The Question
I'm not concerned with whether the current practices mentioned above are right or wrong. Instead, I'd like to understand if there is any logical explanation or guideline (such as a focus on security, which seems to be a common factor in these situations) that determines when to prompt for Login versus Signup when a user comes from ambiguous or undetermined parts of the flow.
Papers or documentation on the subject would be highly appreciated.
