The analysis of subjective factors that influence on group decision making can be performed, for instance, evaluating the negotiation style of the participants involved. Negotiation style can be measured through TKI® scale, a self-report questionnaire that assesses individual’s behavior in conflict situations and describes it along two dimensions: (i) assertiveness and (ii) cooperativeness. In parallel, refined models for a sequential group decision making should include psychological aspects of altruism and reciprocity. As an example, [Gimon and Leoneti 2020] proposed to model psychological components as a combination of two parameters, which are: (i) altruism and (ii) reciprocity, for refining a utility function that models multicriteria group decision making as games. In this work, we aimed to verify if TKI® can be efficiently used for parameters’ definition of the refined utility function and to analyze if the refined utility function’s predictability, within a heterogeneous sequential group decision-making process, can be enhanced by the knowledge of the negotiation style of each participant. This result is important for guiding group decision making process in organizations, since it is a common place in organizations nowadays.