This study investigated how the expectations of others (i.e.,top-down processes) and actual perceived behavior (i.e.,bottom-up processes) influence negotiations during human-agent interactions. Participants took part in several sessions ofthe ultimatum game; we investigated the bargaining strategiesdirected toward the computer agent. To investigate the influ-ence of top-down and bottom-up processes on performance,we designed an experiment wherein (1) participants expectedtheir partners were humans or agents, and (2) agents used dif-ferent types of algorithmic behavior. Results revealed that ir-rational decisions, which are characteristic of human-humaninteractions, emerged when participants believed their oppo-nents were human and when opponent behaviors were ambigu-ous. Further, we found participants adopted different bargain-ing strategies according to their expectations and the agent’sspecific algorithmic behavior. We discuss interplay of the twotypes of cognitive processing in human-agent interaction.