| Human Mental Time Travel (MTT) entails the ability to re-experience past events and anticipate potential future scenarios (Suddendorf & Corballis, 2007). There is some debate as to whether MTT is a uniquely human ability, or whether non-human animals may share some form of MTT as well. The goal in carrying out this thesis was to examine the MTT potential of black-capped chickadees. Black-capped chickadees are a food-storing species from a family (paride) that had not yet been tested for MTT abilities. Chickadees are also year-round residents in North America and experience reduced food availability in winter months. Such characteristics made them an excellent study species to evaluate the prevalence of MTT in avian species.;After establishing in Study 1 that chickadees do possess a form of retrospective MTT, the aim of Study 2 was to determine the timing mechanisms chickadees use in MTT. Past events can be remembered as having occurred at a specific point in the past, or based on an elapsed interval since the event (Roberts & Feeney, 2009). Recent evidence suggests that rats tend to rely on an interval mechanism (Roberts et al., 2008) unless forced to use a temporal framework (Zhou & Crystal, 2009). Two groups of chickadees were forced to use either "when" cues, or "how long ago cues", while a third, standard group, had access to both types of temporal information. Black-capped chickadees differ from rats by readily learning to use "when" cues to solve WWW memory tasks. Importantly, chickadees were able to use "how long ago" cues as well, though not with the same accuracy shown with "when" cues available.;Finally, the purpose of Study 3 (Feeney, Roberts, & Sherry, in press) was to examine the anticipation of future food availability in black-capped chickadees. Supporting the suggestion that chickadees possess a form of MTT, chickadees displayed anticipatory contrast effects of up to 30 min in food consumption decisions (Experiment 1). If initially fed a lesser valued food, followed in the future by a favoured food, intake of the lesser value food was reduced compared to control birds that were not given later access to the favoured food. In Experiment 2, chickadees learned the temporal order of food availability in a foraging task providing less preferred sunflower seeds and highly preferred mealworms, as well as the causal role of initial choices in future food availability. Chickadees successfully avoided sites that would later contain favoured worms during future aviary access, anticipating that worms would only be available after a 30-min delay. It is unlikely that these results can be fully explained by successive negative contrast, anticipatory contrast, or conditioning. Results of Studies 1, 2, and 3 suggest that chickadees are capable of MTT into both the past and the future, and that, like humans, they may use multiple underlying cognitive mechanisms to travel mentally in time.;Keywords: mental time travel, episodic-like Memory, WWW memory, anticipation, comparative cognition, evolution;Study 1 (Feeney, Roberts & Sherry, 2009) was designed to examine "what-where-when" (WWW) memory, a behavioural analogue to episodic memory or retrospective MTT. In an initial Phase, birds searched for hidden seeds and mealworms. After a short (3 h) or long (123 h) delay, memory for the "what", "where", and "when" details of previously encountered foods was tested, with worms degrading after long delays. Accurate WWW memory should cause birds to search for worms after the short delay and seeds after the long delay. In Experiment 1, birds failed to show integrated WWW memory in a home-cage replication of Clayton and Dickinson's (1998, 1999) work with scrub jays, only showing memory for "what" and "where" information. Experiment 2 provided moderate evidence of WWW memory in an aviary with artificial trees. Aviaries represent a more ecologically valid venue for chickadees, which forage and cache items in elevated objects, rather than under sand and debris on the ground like scrub jays. |
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