Evidence for a mnemonic benefit of animate-object interaction: Enhanced retention from animate contact
The importance of animacy has been discovered in the perception literature, the neuroscience literature, and most recently in the memory literature. However, little is known about the extent to which we track the things that agents come into contact with in the environment, and its implications for human memory. Our memory system has been shaped by natural selection to assist in our ability to survive long enough to reproduce our genes. One of the major evolutionary influences on our survival would have been our ability to track, monitor, and predict the behavior of other agents because an agent can be a predator, potential food, potential mate (as described by the animate-monitoring hypothesis; New, Cosmides, & Tooby, 2007), and even a source for contamination as stated by the law of contagion (Rozin, Millman, & Nemeroff, 1986). Across three recall experiments, I examined if the human memory system was structured to prioritize objects that were touched by agents. Experiment 1 tested the incidental memory for objects that were acted upon by agents and other inanimate objects. Participants read sentences that described living and nonliving things interacting with an object, and then were asked to imagine each scene and make an imagery rating. Participants were significantly better at remembering objects that were associated with the agents relative to inanimates. Experiment 2 investigated whether there would be mnemonic benefit for remembering the objects that were interacted with by an agent relative to a nonliving thing if participants were provided with the actors of the action (agent and inanimate) as a cue on a surprise recall test. Participants again created mental images and provided ratings. There was a significant improvement in memory for the target objects that were associated with a living thing compared to a nonliving thing. Experiment 3 examined whether the memory benefit for objects that were touched by agents could be due to the more vivid mental images participants were creating for the agentic sentences as compared to the inanimate sentences. All the sentences were changed to have the exact same action that was performed by the living and nonliving actor. On a surprise cued-recall test where the participants were given the actor and verb as a cue, memory performance for the target objects was superior if that object was touched by an animate relative to an inanimate. The consistent results across all three experiments support the idea that the human memory system is organized to track and remember the objects that living things interact with and physically touch. The mechanisms that allow for the mnemonic benefit are not yet understood, but it may be because there is an awareness (perhaps unconsciously) that living things are salient creatures in our environment that carry sickness, germs, and diseases. It is also possible that humans unknowingly track the objects that are owned or touched by agents because there is the common belief that characteristics of the agent get transferred to the object, which is referred to as the law of contagion. Whether the reason for the enhanced memory is because both of these work in conjunction or context facilitates one over the other, the benefit is clear.
Nairne, Purdue University.
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