Table 1.

The food/cup ratio depicts how many food pieces are distributed among how many cups on a given tray. The probability ratio (PR) relates the likelihood of finding the food on the ‘risky tray’ to the likelihood of finding the food on the ‘safe(r) tray’. Correct choice corresponds to the percentage of trials in which the ‘safe(r) tray’ is chosen.

food/cup ratio on each tray	1/1 versus 1/2	1/1 versus 1/3	1/1 versus 1/4	1/1 versus 1/5	1/1 versus 1/6	1/1 versus 2/4	1/1 versus 2/3	1/2 versus 1/4	1/2 versus 2/6	1/3 versus 1/6	2/3 versus 3/6	2/2 versus 4/6	2/2 versus 3/6
probability ratio (PR) between trays (Plow/Phigh)	0.5	0.33	0.25	0.2	0.17	0.5	0.67	0.5	0.67	0.5	0.75	0.67	0.5
correct choice (%)	44	69	78	75	84	38	41	63	34	44	38	44	42