Final answer:
After planning poker results in a spread of estimates, allowing team members with extreme scores to explain their reasoning and working towards consensus through further discussion is the appropriate next step.
Step-by-step explanation:
The next step after a planning poker session results in estimates from the development team members of 1, 5, 5, 5, and 8 is to allow the team members who had extreme scores to explain their viewpoints and redo the estimation process until consensus is achieved. This is considered a standard practice in Agile methodologies and promotes team collaboration and understanding. It ensures that all perspectives are considered, and the team agrees upon a reasonable estimate for the user story based on their collective knowledge and experience.