Halliday & Matthiessen (1999: 580):
Painter (1993) documents how one child first learned to construe mental projection: he began with figures in which he himself was the Senser. The system made it possible for him then to generalise his own experience of consciousness by construing other persons in the Senser role, as he built up a model in which this role could be occupied by any conscious (prototypically human) being.