“…The non-humanoid robots used in these articles varied in morphologies and functionalities (Figure 1). Eleven (44%) articles adopted readily available robots developed in previous work [13][14][15]22,52] or commercially available [9,18,20,28,50,53], while another thirteen (52%) articles designed and prototyped robots for the specific purpose of investigating emotional expressions [17,19,21,23,27,29,45,49,[54][55][56][57][58]. The remaining one article implemented the design from another robot using Lego robot parts [26].…”