The Effect of Virtual Agent Warmth on Human-Agent Negotiation - Pooja Prajod; Mohammed Al Owayyed; Tim Rietveld; Jaap-Jan van der Steeg; Joost Broekens (Proceedings of the 18th International Conference on Autonomous Agents and MultiAgent Systems, AAMAS '19, Montreal, QC, Canada, May 13-17, 2019, 2019)