The pig dice game. a, Trial types. Each trial started with a rolling phase for 1.5–3.5 s, after which the random outcome was shown. If a throw
yielded a pip number between 2 and 6, the pip number multiplied by 10 DKK was added as reward to the accumulated earnings
for the round. After each rewarding throw, subjects chose whether to continue rolling the die (i.e., CONTINUE trial) or to
stop and bank the cumulated gain (i.e., STOP trial). If the pip number of a throw was 1, participants lost the entire gain
that had been accumulated during the round (LOSS trial). b, Relation between expected value for additional gains (green line) or losses (red line) and the accumulated earnings in DKK
during a gambling round. The expected value of the additional gain per throw (green line) remained constant during a gambling
round and was derived by the mean pip number per rewarding throw multiplied by the probability to win and the factor 10 
. The expected value of loss per throw (red line) steadily increased during the gambling round and equaled the accumulated
sum multiplied by the loss probability (1/6). The coordinate where the red and green lines cross each other indicates the
point where expected values for additional gain and loss were equal. At this point of the game, corresponding to accumulated
earnings of 200 DKK, the player ought to stop because the expected value of losing starts to outweigh the expected value of
the additional gain. c, Logistic regression modeling of individual stop probability. Stop probability was described as a sigmoid function of accumulated
sum during sequential gambling. The CE corresponds to the accumulated earnings (in DKK) where the likelihood to stop equals
the likelihood to continue throwing a die (dashed lines). d, Logistic stop probability functions of all participants (n = 18). There were considerable interindividual differences in the distribution of choice behavior. No participant showed
a choice behavior that matched the optimal gain-maximizing strategy. The objectively optimal choice behavior is illustrated
by the red line, representing a step function with an abrupt switch from continuing to stopping when the accumulated earnings
are DKK 200.
