The aim is to create an almost neutral but slightly benign setting or field in which the varying but controlled stresses of the task will project each candidate's group-effectiveness. The observer team must keep in mind that while they are observing candidates in a group task, they are part of that field: to the extent that they are felt to be benign and friendly, the group will project itself more-spontaneously: such frustrations as they meet will arise from the task and the group itself:

They should be visible to the group, yet unobtrusive and inconspicuous. Observers who gather in knots, laugh misguidedly, criticise noticeably, converse in an over-loud sotto voice, are too obvious and too frequent in their note-taking, too restless in their movements, or otherwise fail to efface their personalities, may be felt as unsympathetic, "superior" or even hostile. The observer who obtrudes his personality is unfair to the candidates and the PSG, and is detracting from the value of the test: consistent failure to appreciate the need for self-effacement suggests unsuitability for work in selection. Visiting observers may have to be instructed in these matters: the observation field-where men are at work-is no more a place of entertainment than the Sjt-tester's testing hall.