Does the presence of a conspecific increase or decrease fear? Neophobia and habituation in zebra finches

Neophobia, defined as the fear of novelty, can be exhibited when individuals encounter unfamiliar stimuli in their environment. Neophobia has been shown to both increase and decrease when individuals are with conspecifics. An increase in latency to contact new objects can be explained by the negotiation hypothesis, which proposes that individuals in groups will negotiate who will approach novelty first, thereby delaying the first contact. This negotiation process could co-occur with and mask a potential effect of risk dilution, where individuals in groups should approach novel objects faster due to lower perceived risk in a social than non-social context. Here, we aimed to test the risk dilution hypothesis using an experimental set-up that precluded negotiation among group members by physically separating dyads during social trials. We presented zebra finches (Taeniopygia guttata) with different novel objects in both social and non-social contexts. We also repeated the presentation of each object to investigate, for the first time to our knowledge, the effect of social context on the change in neophobia over repeated encounters (i.e., habituation). We found that social context increased the latency to approach a novel object upon first presentation of objects (i.e., increased neophobia), but these latencies decreased faster over repeated presentations of the objects (i.e., faster habituation) compared to the non-social context. These results do not provide support for the risk dilution hypothesis regarding first encounters with objects (neophobia) but seem to support it over repeated object presentations (habituation). This suggests that the effect of social context is different on neophobia and habituation, possibly because they recruit different cognitive mechanisms. Future studies should investigate the impact of ecological and social conditions on decision-making upon first versus subsequent encounters with a novel object in social animals, as both processes can impact fitness costs and benefits of novelty responses.

Automated summary

The study found that social context increased neophobia during the first encounters with novel objects, but neophobia decreased faster over repeated presentations, supporting habituation. This suggests that the impact of social context differs between neophobia and habituation, possibly involving different cognitive mechanisms. Future research should explore the effects of ecological and social conditions on decision-making in social animals during initial versus subsequent encounters with novel objects, as these processes can affect the fitness costs and benefits of responses to novelty.