It's one of those things I learned in the many, many trainings and seminars I attended in the past. People's maturity in terms of their work attitude can be classed into four, depending on their capabilities and their interest in the task. These maturity levels are simply called M1, M2, M3, and M4. How you should treat a person depends on their maturity levels.
M4 people are considered to be matured. They are interested in their work and they are capable of carrying out their task, if not highly qualified. The best way to treat them, if they are under your supervision, is to let them be. Meddling would only hinder their efficiency. But you need to make sure that they are on track in terms of shared goals... Thus you only need to remind them about it in whatever way appropriate.
M3 people may be capable but they are not so interested in their work. They might have been forced by circumstance to fulfill the task. They need a lot of coaching... of encouragement... With a lot of patience, they can move on to become M4's.
M2 people, on the other hand, are very interested to fulfill a task although they are neither knowledgeable about it nor do they have the skills to fulfill it. For some there is that ardent desire to learn. For others there is that nostalgia of fulfilling a dream. On the practical sphere, one only needs to teach them the knowledge and skills they lack. Again, with patience, they can move on to become M4's.
M1 people are those who are neither interested on their work nor are they capable of carrying out their work for lack of skills, knowledge, or some other disabilities. They need to be coached. They need to be taught. The question is: when do we raise the white flag?
I very seldom give up on a person. I spur them on no matter what. Sometime, though, they themselves give up. Anyway, it's a case to case basis...
It is important of course to match assigned task to maturity levels. I always believe that there is always a task that M1's can do that can contribute to the team, even if it requires them to simply carry something or the like... Each one in the team should also acknowledge each one's maturity level, and respect each other.
This little lesson on the M Factor is applicable not only to the construction site. It has helped me even in my dealings with people in executive board rooms. Believe it or not, even the rich and powerful can sometimes be immature. I've also handled geniuses who showed immaturity to some extent. But there is a task to accomplish, and these people somehow find their way into your team.
There is then the need to assess each person's maturity level early on. It requires another set of skills to do so. Sometimes I engage them in a "diagnostic" conversation. Complicated personalities require a little more research. The bottom line is to know your men before you lead them.
I hope these two new hires would learn the tricks soon....