Table 1:

13 Task Comprising the PCTB, Number of Items and Trials (Based on Herrmann et al. 2007)

Physical Cognition
Spatial Memory	Location of hidden baited reward (1 item, 3 trials)
Object Permanence	Tracking of reward atter invisible displacement (3 items, 9 trials)
Rotation	Tracking location of reward after rotation (3 items,9 trials)
Transposition	Tracking rewards after location changes (3 items, 9 trials)
Quantify Discrimination	Discriminate quantity (1 item, 13 trials)
Causality (Noise)	Causal understanding of produced noise by hidden rewards (2 items, 6 trials)
Causality (Visual)	Causal understanding of appearance change by hidden rewards (2 items, 6 trials)
Tool Use	Use a lollipop stick to retrieve out of reach food (1 item, 2 trials)
Tool Comprehension	Understanding of functional and nonfunctional tool properties (5 items, 15 trials)
Social Cognition
Comprehension	Understanding communicative cues to select hidden food location (3 items, 9 trials)
Production	Producing communicative gestures in order to receive hidden food (1 item, 4 trials)
Attention State	Using communicative signals according to attention state of audience (4 items, 4 trials)
Gaze Following	Following an experimenters gaze direction toa target (3 items, 9 trials)

Note that each chimpanzee was tested twice on the PCTB tasks; thus, for the performance measures in this study, the number of trials administered to each subjects was twice as many as reported in the Table.