Concept testing has one failure mode and everything else is detail: people are polite to strangers, and a badly framed question converts that politeness into a green light.
What to put in the public brief
- That it is written feedback on an early idea
- Roughly the category, so people can self-select on relevance
- How long a response you expect
- That critical responses are paid the same
Keep the concept, the mockups and anything identifying the company private. This is the task type where the brief itself is the confidential asset.
What to put in the private instructions
Ask about the last time, not the next time
"When did you last deal with this, and what did you do" beats any question containing the word "would".
Describe the concept in one paragraph, then ask what it does
If their answer is not your intent, stop reading the rest of the responses and fix the paragraph first.
Ask what would have to be true
"What would need to be the case for this to be worth paying for" surfaces the objection without inviting a verdict.
Say plainly that a negative response is wanted and paid
And mean it, because approving only the enthusiastic responses teaches the marketplace what you actually want within a week.
Proof worth requiring
Ask for
Written answers in their own words, and one line on how relevant the category is to them. Relevance is the variable that decides how to weight everything else.
Do not ask for
A score out of ten. It compresses the objection into a number and then you will average the numbers, and the average of an objection is nothing.
When this task type is the wrong tool
If the product exists and can be used, stop asking about the concept and test the thing. Behaviour beats stated preference every time it is available.
If you need a specific professional population — clinicians, developers, procurement — general marketplace recruitment will underdeliver. Research participant recruitment covers what changes when the population is narrow.