Figure 2.

Instrumental learning and generalization to the PIT stage after tryptophan depletion (right graph, TRP−) and after the balanced amino acid drink (left graph, BAL). The proportion of correct choices [p(correct)] are divided over the four different types of instrumental stimuli: go-approach, nogo-approach, go-withdrawal, and nogo-withdrawal. Time is represented by bins of 10 trials for each type of stimulus at the beginning (I1) and the end (I2) of the instrumental training and at the beginning (PIT1) and the end (PIT2) of the PIT stage. Error bars represent SEM.