PhD Defense of Eszter Szabó: The Representation of the Absence of Objects
The Department of Cognitive Science cordially invites you to the public defense of the PhD thesis of
The representation of absence of objects
Primary supervisor: Ágnes Kovács
Secondary supervisor: Gergely Csibra
While linguistic negation is a fascinating tool to capture the absence of objects, we know little about how these thoughts emerge. In this work, first, we aimed to investigate the linguistic negation acquisition and the nature of the first meanings of the negative statements; second, we targeted language independent representations of presence/absence available for young infants and non-human animals. In Study 1 and 2 we inspected the development of negation comprehension between 15 and 24 month in human infants. In Study 1 we asked whether a domain general or alternatively, a limited conceptual understanding supports the initial understanding of negation expressing absence. We found a parallel development for understanding syntactically and functionally different negative utterances, supporting a common conceptual basis for negation already at 18 months. While in Study 1 infants were able to encode absence and use it to find the presence of an object, in Study 2, we tested negation comprehension when it does not evoke the implication of a positive alternative (i.e. the only implication is ‘nothing’). We found a more prolonged pattern for negation understanding in Study 2 compared to Study 1. In Chapter 3 we tested young domestic chicks’ encoding of the presence and the absence of an object. We found sex-dependent evidence in their looking behavior, suggesting a capacity for encoding absence. In Chapter 4 we measured the neural correlates of different types of object disappearances in 6-month-old infants. Object maintenance (of presence) evoked prefrontal and temporal activation when an object was occluded; in contrast no specific activation was found for objects that vanished or mingled among other identical objects.
Our findings point to human infants’ readiness to understand negation expressing absence, likely based on domain general cognitive and linguistic tools. However, encoding absence is not language-dependent ability; such information is also available for pre- and non-linguistic creatures, but unlike encoding presence, it is not an automatic process. We propose that absence depends on categorical representations, and on possible mental structures expressing contrary concepts.