Striatal dopamine D1 receptors are involved in the dissociation of learning based on reward-magnitude

► We trained pigeons on visual discrimination tasks resulting either in a small or a large reward. ► Following control-injections the speed of acquisition depended on reward magnitude. ► Following injections of D1-antagonist, the effect of reward-magnitude vanished. ► Discrimination between reward-magnitudes was unaffected by D1-antagonist. ► The reward-influence on learning depends on striatal dopamine receptors.