Okay so we have faced the problem. What do we do?
It may be prudent, to obtain bye-in from the person who will be looking for the needle in the haystack. Especially if this is a boring task you will need to explain to the person why it is necessary to find the needle and how it fits in with the vision/mission.
In case this is a repetitive scenario, you may want to track how many times each resource has failed to find the needle and penalize the one at the top. If this specific scenario is not repetitive you may want to club with similar scenarios where the group overall is repetitive. This can also be subjected to statistical analysis (more on the statistical analysis in another post here).
One way, as I suggested earlier, is to create a verification procedure that is shorter than looking for the needle in the haystack itself. Ask a peer to carry out the verification – call him the “supervisor” (he will be better motivated this way).
Another way to handle this problem is through the usual reward/punishment strategy. Either offer a reward for finding it, or offer a punishment for not finding it. The reward does not have to big, neither does the punishment need to be huge. Token punishments are enough. For example, a task required everyone to fill up a template, and one person to consolidate each Friday. People would need reminders, etc – so we decided that whoever is the defaulter the highest number of times would get the task of consolidating for the next few weeks. Then on to the next defaulter.