Understanding object-directed intentionality in Capuchin monkeys and humans
Abstract
Understanding intentionality, i.e. coding the object directedness of agents
towards objects, is a fundamental component of Theory of Mind abilities. Yet it is
unclear how it is perceived and coded in different species. In this thesis, we present
a series of comparative studies to explore human adults’ and Capuchin monkeys’
ability to infer intentional objects from actions.
First we studied whether capuchin monkeys and adult humans infer a potential
object from observing an object-directed action. With no direct information about
the goal-object, neither species inferred the object from the action. However, when
the object was revealed, the monkeys retrospectively encoded the directedness of
the object-directed action; unexpectedly, in an adapted version of the task adult
humans did not show a similar ability.
We then adapted another paradigm, originally designed by Kovács et al (2010),
to examine whether the two species implicitly register the intentional relation
between an agent and an object. We manipulated an animated agent and the
participants’ belief about a ball’s presence behind a hiding screen. We found no
evidence showing that humans or monkeys coded object-directedness or belief.
More importantly, we failed to replicate the original results from Kovács et al’s study,
and through a series of follow up studies, we questioned their conclusions regarding
implicit ToM understanding. We suggested that, instead of implicit ToM, results like
Kovacs et al’s might be interpreted as driven by “sub-mentalizing” processes, as
suggested by Heyes (2014).
We conclude that so called ‘implicit ToM’ may be based upon the computation
of intentional relations between perceived agents and objects. But, these
computations might present limitations, and some results attributed to implicit ToM
may in fact reflect “sub-mentalizing” processes.
Type
Thesis, PhD Doctor of Philosophy
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