Baby face enlarges perceived reachable space.

Humans perceive reachable space (RS), the space within which they judge themselves to be able to touch or grasp an object or another person when extending their arms. Previous studies have reported that perceived RS toward another person expands when the person displays an angry facial expression, suggesting that humans adjust their interaction range based on others' facial characteristics. However, how babies' faces which have cuteness as a characteristic influences perceived RS remains unclear. This study investigated the effect of baby faces and the cuteness of others' faces on perceived RS. Two experiments were conducted using facial stimuli of babies and younger adults in a virtual reality environment. Experiment 1 measured perceived RS by focusing on facial cuteness, whereas Experiment 2 examined whether the results of Experiment 1 could be explained by the size constancy of the face stimuli. Experiment 2 also measured the perceived distance of the face stimuli. Participants judged whether they could reach the face stimuli at various distances while being instructed not to move their actual hands. The results of Experiment 1 demonstrated that perceived RS was not modulated by facial cuteness but was significantly larger for baby faces than for younger adult faces. Experiment 2 replicated the results of Experiment 1 and showed that size constancy did not account for perceived RS differences between face age conditions because perceived distances did not differ significantly between face age conditions. These findings suggest that baby faces, rather than facial cuteness, contribute to the expansion of perceived RS.