Three assessors Psychologist, GTO and IO assess the candidate independent of each other. They do not interact with each other regarding performance of any candidate.
Also each technique has its strong points eg physical courage and stamina can best be seen by the GTO similarly other techniques are strong in their own areas.
It is highly possible that psych has recommended a candidate and others (both GTO and IO) or any one of these does not recommend the candidate and ultimatwly the candidate is not recommended.
A candidate can get recommended in the following manner:
If the candidate is cleared by all the three assessors then he is recommended.
If the candidate is cleared by two assessors and not cleared by one. Then the one who has not cleared is asked if he has serious reservations or is he willing to clear the candidate. If he says he is willing to clear then the candidate is recommended, if his answer is negative then the candidate is dropped.
In stage one if there is a doubt about the candidate he is given the benefit of doubt and taken to stage two. In stage two if there is a doubt then the benefit of doubt is taken by the organisation and the candidate is dropped.
All three assessors have same weightage.