better (or at least the same) group performance. Then, instead of the summation of individual $z$-scores , one will get a more complicated formula for the decision.

Direct Signal Sharing {#s:dss}
---------------------

#### Model {#model-4 .unnumbered}

Group members share both their perceived stimuli $x_i$ and their $\sigma_i$. The group decision depends on the sign of $\sum_{i=1}^n x_i/\sigma_i^2$. This model requires each $P_i(c)$ to be normal .

#### Motivation {#motivation-4 .unnumbered}

As for the WCS, we assume that the value $x_i$ is the stimulus perceived by $i$-th participant and has a distribution with the density $P_i'(c)$, as it is in [@Sorkin2001]. The group possesses complete knowledge about the characteristics of its members and their perceptions, so its effectiveness is hindered only by the skill of the participants, not by communication. This model constitutes the upper bound for group performance, provided that the stimuli are fully defined by their stimulus values (and perceived according to the discussed model). In the case of a more complex, non-perceptive task, it is possible for a group to exceed this bound [@Hill1982]. For example, this could occur when participants’ skills complement each other. People know the strength of the stimuli but also their own sensitivity. If 