Although humanoid robots are being designed to assist people in various tasks, there remain gaps in our understanding of the perceptions that humanoid faces evoke in the user. Understanding user perceptions will enable design of robots suited for the target user group. We assessed younger and older adults' preferences for robot appearance out of three levels of human-likeness. Preferences for robot appearance differed between younger and older age groups. A majority of older adults preferred a human appearance for their robot whereas the intermediate level of appearance (mixed human-robot) was least popular among them. Younger adults' preferences were more distributed across the three levels of human-like appearances. Moreover, preferences for appearance depended on the robot task. The underlying reasons for task-specific preferences toward highly human-looking versus less human-looking robots are also discussed.