People talk to their plants, pray to humanlike gods, name their cars, and even dress their pets up in clothing. We have a strong tendency to give nonhuman entities human characteristics (known as anthropomorphism), but why? In a new report in Current Directions in Psychological Science, a journal of the Association for Psychological Science, psychological scientists Adam Waytz from Harvard University and Nicholas Epley and John T. Cacioppo from University of Chicago, examine the psychology of anthropomorphism.

The term anthropomorphism was coined by the Greek philosopher Xenophanes when describing the similarity between religious believers and their gods -- that is, Greek gods were depicted having light skin and blue eyes while African gods had dark skin and brown eyes. Neuroscience research has shown that similar brain regions are involved when we think about the behavior of both humans and of nonhuman entities, suggesting that anthropomorphism may be using similar processes as those used for thinking about other people.

Anthropomorphism carries many important implications. For example, thinking of a nonhuman entity in human ways renders it worthy of moral care and consideration. In addition, anthropomorphized entities become responsible for their own actions -- that is, they become deserving of punishment and reward.

Although we like to anthropomorphize, we do not assign human qualities to each and every single object we encounter. What accounts for this selectivity? One factor is similarity. An entity is more likely to be anthropomorphized the more similar it appears to humans (for example, through humanlike movements or physical features like a face). Various motivations may also influence anthropomorphism. For example, lacking social connections with other people might motivate lonely individuals to seek out connections from nonhuman items. Anthropomorphism helps us to simplify and make more sense of complicated entities. The authors observe that, according to the World Meteorological Organization, "the naming of hurricanes and storms -- a practice that originated with the names of saints, sailors' girlfriends, and disliked political figures -- simplifies and facilitates effective communication to enhance public preparedness, media reporting, and the efficient exchange of information."

Anthropomorphism in reverse is known as dehumanization -- when humans are represented as nonhuman objects or animals. There are numerous historical examples of dehumanization including the Nazis' persecution of Jews during the Holocaust and torture at the Abu-Ghraib prison in Iraq. These examples also suggest that those engaging in dehumanization are usually part of a cohesive group acting against outsiders -- that is, individuals who feel socially connected may have an increased tendency towards dehumanization. The authors note, "Social connection may have benefits for a person's own health and well-being but may have unfortunate consequences for intergroup relations by enabling dehumanization."

The authors conclude that few of us "have difficulty identifying other humans in a biological sense, but it is much more complicated to identify them in a psychological sense."