Fig. 1.

Experimental design. (A) During encoding, participants studied drawing-token associations. Half of the drawings were followed by a reward token (‘reward source’), half were followed by a zero token (‘zero source’). (B) At recognition, old and new drawings were presented in two blocks that featured either a ‘Reward?’ cue or a ‘Zero?’ cue. These cues prompted participants to make a source memory judgment for each drawing. A three-point confidence rating scale (low, medium and high) followed each drawing (not shown). Sixty drawings were tested under each cue (20 reward source, 20 zero source and 20 new).