Abstract:
A prominent psychological theory on early cognitive development is Spelke’s
Core Knowledge (CK) hypothesis (Spelke, Breinlinger, Macomber, & Jacobson,
1992), which posits that human infants, and possibly other species, are guided by
innate understandings of how object movements, classification and quantification are
governed by physical laws and, further, how agents are capable of perceptions and
purposive action. CK is a set of cognitive building blocks, which serve as the
foundation for more complex cognition such as acquisition and use of symbol
systems pertaining to language and mathematics (Spelke, 2000). Evidence points to
four core systems of knowledge: representation of number, object, space (or
geometry) and agency. Investigation of spontaneous CK in nonhuman species in the
wild is fundamental to understanding the ecological validity and evolutionary context
for a set of systems that is proposed to be universally embedded. The bold,
inquisitive manner, naïve fearlessness and unique insect caching behaviour of wild
North Island robins (Petroica longipes) presents a unique opportunity to identify and
characterise CK in a new model system. Six studies were conducted with the aim of
investigating core developmental cognition in robins.
The first three studies focused on perception of numerical quantity. Study 1
investigated the ability to discriminate between both large and small quantities,
finding that robins successfully discriminate between unusually large quantities
independent of ratio. Study 2 explored quantity discrimination in which summation of
items is spatially distributed across an array, and found that while robins perform
successfully with small numbers, the task presented substantially more cognitive
demand. Study 3 measured robins’ reactions to computation by presenting simple
addition and subtraction problems in a Violation of Expectancy (VoE) paradigm,
finding that robins search longer when presented with a mathematically incongruent
scenario.
The last three studies focused on perception of agency. Study 4 investigated
robins’ response to gaze direction in humans in a competitive paradigm, and found
that they were sensitive to human gaze direction in all conditions but one. Study 5
explored perception of physical capability in humans, and results indicated that limb
visibility significantly influences pilfering choice. Study 6 examined robins’ perception
of animacy in prey, finding that in a VoE paradigm, robins’ expectation of hidden prey
continuity varies depending on mobility and animacy.
Taken together, the results of these six studies suggest that while supportive of
fundamental characteristics defining basic Core Knowledge in many ways, some
unique results in the cognitive abilities of this biologically naïve species shed new
light on our growing understanding of the shared basis of cognition. A deeper look at
avian performance in core developmental tasks, especially in a naïve wild
population, can offer new insights into sweeping evolutionary theories that underpin
basic cognitive mechanisms.
