While your observation of the casual attitude shows a keen interest and observation on your part, the problem is that you cannot do anything against this person for what you perceive as their attitude, unless such attitude disrupts or influences the rest of your staff, staff events, or performance. This is not the end of it though...
A Perceived Casual Attitude
A perceived casual attitude is normally an indication of one of the following:
• In a social atmosphere, arrogance.
Causes:
• An inability to connect socially - This could be because of underlying shyness, serious personal problems, being from another area or culture than the rest of the group, or a physical impediment that the person feels ashamed about. Remember that arrogance is normally a personal means of self-justification and a self-defense mechanism to keep others at a distance. It could also be an indication that the person regards themselves as better than the rest or feels intellectually superior to the rest.
Solution:
• Investigate - without the subject knowing (that will simply set up barriers) - what the root cause is behind the attitude.
• If it is shyness, make sure to actively include the person in the group by asking their opinion or relying on their participation in a public fashion.
• If it is personal problems, try to find out more without being intrusive - simply reassure the person that as HR, you are concerned about them.
• If it is a cultural problem, concentrate efforts on the group - in public - that in a work environment, all are equal and on the same footing.
• If it is a physical impediment, ignore the condition, but increase the pressure on the person to participate.
Boredom
It is possible that this person is simply capable of much more than they are allowed to be and finds the situation boring or menial.
• Try to assess their talents and/or aptitude, and then compare their current level of work assignment to their ability.
• It is possible that they are simply not intellectually stimulated by the environment.
• If this is the case, try to engage the person in problem-solving on their own level - challenge their intellect, and see whether that improves the situation. My guess is that their attitude will improve once they feel that they are delivering a more meaningful contribution.
If all of this fails, and you still feel that their attitude is being disruptive, put them through a conduct-counseling session, and follow the full steps to ascertain that the person does not feel that the matter is becoming constructive to their dismissal.
Hope this helps...