When randomly assigning participants to experimental roles and the according payment prospects, participants seem to receive "manna from heaven." In our view, this seriously questions the validity of laboratory findings. We depart from this by auctioning off player roles via the incentive compatible random price mechanism thus avoiding the selection effect of competitive second price auctions. Our experiment employs the generosity game where the proposer chooses the size of the pie, facing an exogenously given own agreement payoff, and the responder is the residual claimant. We find that entitlement crowds out equality seeking and strengthens efficiency seeking. More generally, we find that inducing entitlement for the roles in which participants find themselves makes a difference. Interpreting participants' willingness to pay for their role as their aspiration level further allows to test satisficing and explore "mutual satisficing." We find that responder participants apparently do not anticipate proposer generosity in aspiration formation. © 2013 Springer Science+Business Media New York.