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Abstract

Humans exhibit a dynamic system of early development, where shifts in motor development interact with shifts in cognitive development. Milestones in locomotion repeatedly emerge with overlapping milestones in object permanence, spatial representation, reasoning, and attention. Still, we know very little about how these relationships compare in a nonhuman primate with divergent cognitive and motor development but with many analogous skills and developmental sequences. I present longitudinal behavioral and cognitive data from birth through the first years of life in a population of free-ranging rhesus macaque monkeys on the island of Cayo Santiago, Puerto Rico that support dynamic relationships between spatial cognitive development and early experience in a nonhuman primate. Chapter 2 examines emergent spatial coding systems and whether yearling rhesus macaques will apply a consistent spatial coding strategy to interpret small-scale visuospatial tasks in rotational movement. Participants (N = 37) were exposed to two displacement scenarios consistent with either allocentric or egocentric interpretations of space, and while participants appeared to respond to change in both conditions, they did not differentiate between the conditions overall. However, there was variation in individual expectation, where the majority consistently increased their attention to one condition as a possible violation of their expectation and decreased their attention to the other independent of the order of exposure. Individuals could be categorized as “allocentric” or “egocentric” based on these looking time measures. “Egocentric” individuals that increased their attention to the allocentric condition and habituated to the egocentric condition also spent more time investigating a rotated image than “allocentric” individuals, supporting a connection between the spatial coding of multiple objects and the speed of processing a single rotated object. Chapter 3 uses the same individuals (N = 15 to 39) to examine interactions in cognitive development over the first two years. Participants improved most on gaze following in their first year and improved in their participation on search tasks from their first to second year. Moreover, they exhibited a consistent positive correlation between performance in object permanence and means-ends support problem tasks over the first two years, and “allocentric” coders consistently outperformed “egocentric” coders, illustrating dynamic relationships between these cognitive abilities. Though, participants did not show any overall evidence for advanced object permanence in solving invisible displacements or causal reasoning in support problems. Chapter 4 continues to examine dynamic cognitive development in the context of early experience. In humans, independent movement and changes in posture can facilitate spatial cognitive development, but it is unclear how this relationship might persist in rhesus macaques with an earlier locomotive onset and quadrupedal gait. Though, rhesus macaques and humans do share a similar early socioemotional environment in which maternal-infant relationships are particularly formative. Over the first year, individuals (N = 38 to 44) exhibited a steady increase in their independent movement, which was highly correlated with maternal weaning behaviors, but high rates of maternal abuse and rejection over the first year consistently corresponded with low participation rates in search and support problem tasks and an “egocentric” attention in the spatial coding looking time task. However, those that consistently recovered the reward and qualified for stage V object permanence in their first year of exposure to the A-not-B object permanence task exhibited significantly higher rates of independent locomotion and social play in their first year than those that appeared to search randomly that were independent of their rates of maternal abuse and rejection. These collective discoveries support analogous dynamic systems of spatial cognitive development and early experience in nonhuman primates and humans despite some divergence in their cognitive repertoire and early motor development. These results also substantiate novel methods for approaching these questions with spontaneous testing in a free-ranging population.

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