TABLE 1.

Details of the gamble pairs used in the task, including the probabilities of each of the winning and losing outcomes (in points) of each gamble option

	Gamble 1				Gamble 2
	Outcome 1	Probability 1	Outcome 2	Probability 2	Outcome 1	Probability 1	Outcome 2	Probability 2
1	80	0.5	−80	0.5	60	0.25	−20	0.75
2	10	0.5	−20	0.5	130	0.25	−50	0.75
3	70	0.5	−170	0.5	20	0.5	−120	0.5
4	30	0.5	−50	0.5	10	0.5	−30	0.5
5	50	0.5	−30	0.5	80	0.5	−60	0.5
6	150	0.5	−10	0.5	190	0.5	−50	0.5
7	160	0.5	−80	0.5	60	0.75	−20	0.25
8	40	0.5	−80	0.5	20	0.75	−140	0.25
9	70	0.5	−50	0.5	20	0.75	−20	0.25
10	200	0.5	−30	0.5	130	0.75	−50	0.25
11	50	0.5	−30	0.5	80	0.75	−200	0.25
12	50	0.5	−30	0.5	40	0.75	−80	0.25
13	120	0.25	−60	0.75	60	0.25	−40	0.75
14	10	0.25	−50	0.75	40	0.25	−60	0.75
15	100	0.25	−80	0.75	20	0.75	−200	0.25
16	80	0.25	−40	0.75	20	0.75	−100	0.25
17	140	0.25	−30	0.75	20	0.75	−5	0.25
18	20	0.75	−100	0.25	110	0.25	−50	0.75
19	60	0.75	−60	0.25	150	0.25	−10	0.75
20	60	0.75	−20	0.25	200	0.25	−10	0.75
21	100	0.75	−140	0.25	60	0.75	−20	0.25
22	100	0.75	−80	0.25	80	0.75	−20	0.25
23	10	0.75	−70	0.25	40	0.75	−160	0.25
24	80	0.75	−40	0.25	100	0.75	−100	0.25
25	150	0.5	0	0.5	0	0.5	−50	0.5
26	10	0.5	−200	0.5	200	0.75	−10	0.25

Gamble pairs 1–24 have equal expected value, i.e. (outcome 1 × probability 1) + (outcome 2 × probability 2). Gamble pairs 25 and 26 are catch trials with noticeably different expected values.