Human decision making has demonstrated imperfectness and essential deviation from rationality. Emotions are a primary driver of human actions and the current study investigates how perceived emotions may affect the behavior during the Ultimatum Game (UG), while recording event-related potentials (ERPs) from scalp electrodes. We observed a negative correlation (p < 0.001) between positive emotions, in particular happiness, and the amount offered by a participant acting as a Proposer in the UG. Negative emotions, in particular fear, showed a positive correlation (p < 0.05) with the offer. The ERPs revealed invariant components at short latency in brain activity in posterior parietal areas irrespective of the Responder or Proposer role. Conversely, significant differences appeared in the activity of central and frontal areas between the two conditions at latencies 300-500 ms.