Figure 5. Human decision-making Experiment-2.

(A) A screen-shot from the beginning of each trial. The meaning of targets ('Find out now' or 'Keep it secret'), the duration of $T_{\text{delay}}$ (the number of hourglass), and the chance of rewards (the hemisphere $=0.5$) were indicated explicitly. (B) The number of hourglasses indicated the duration of $T_{\text{delay}}$ until reward. One hourglass indicated 5 s of $T_{\text{delay}}$. When $T_{\text{delay}}=1$ s, a fraction of an hourglass was shown. This was instructed before the experiment began. The delay condition $T_{\text{delay}}$ was changed randomly across trials. (C) The task structure. The task structure was similar to Experiment-1, except that the 0% info target (Blue) was followed by a no-info cue, and an image symbolizing the lack of reward was presented when no reward outcome was delivered. (D) Results. Human participants (n=31) showed a significant modulation of choice over delay conditions [one-way ANOVA, F(4,150)=3.72, p=0.0065]. The choice fraction was not different from 0.5 at short delays [1 s: $t(30)=0.83$, $p=0.42$ 5 s: $t(30)=0.70$, $p=0.49$, 10 s: $t(30)=0.26$, $p=0.80$] but it was significantly different from 0.5 at long delays [20 s: $t(30)=2.86$, $p=0.0077$, 40 s: $t(30)=3.17$, $p=0.0035$], confirming our model’s key prediction. The mean and +/- SEM are indicated by the point and error bar.

DOI: http://dx.doi.org/10.7554/eLife.13747.014