Saying enough, without saying too much: Linguistic and cognitive factors in effective referential communication

Reference is a fundamental aspect of human communication. From infants' early pointing gestures to the formulation of complex referential expressions (e.g., 'the large cookie jar on the top shelf'), speakers must develop linguistic and cognitive abilities that allow them to refer to the world around them in effective ways. The focus of this research project is on the development of those abilities that make for effective referential communication. A key issue for models of referential communication is the amount of information included in a referential expression. In theory, speakers should not specify more information than is necessary to secure unique reference. Thus, in a situation where there is only one cookie jar, asking for 'the cookie jar' should be enough for the hearer to identify the object. However, it has been repeatedly shown in psycholinguistic studies that adults tend to produce over-informative referential expressions, especially with colour adjectives (e.g., 'Could you bring me the red cookie jar over there?'). Our theoretical hypothesis is that such over-informative uses may be efficient in object requests, rather than violating information constraints. The project will investigate two factors that may contribute to the effectiveness of referential communication: linguistic factors (e.g., whether adjectives appear before or after the noun in a given language) and cognitive factors (e.g., whether memory capacity correlates with effective referential communication). Moreover, the projec t will investigate the development of effective referential abilities across the lifespan (from primary school to old age). For this purpose, we will use interactive tasks with pairs of participants who will have to jointly arrange various objects while w e record their language production and eye movements. Overall, this project will help us determine what is effective in referential communication and how effectiveness develops. The results of the first studies with adults have been very promising, with eye-tracking data revealing that over-specific colour adjectives facilitate object recognition for the hearer. Eye-tracking studies with children have also revealed that reference plays a very important role in social cognition tasks. Later studies have revealed that blind children (who perform the same referential communication tasks in the tactile modality) are also sensitive to ambiguity and tend to produce sufficient information to request a certain toy. Also, new studies with adults have revealed that perceptual contrast (e.g., differences in size, colour or object type in a display) trigger the use of adjectives in referential communication, which is again consistent with an efficiency account. The studies from 2016-2017 have shown that children start developing strategies for efficient referential communication around age 3 years. This has been observed both in Norwegian and Spanish pre-school children. An eye-tracking component of this study (investigating how children visually explore a display before requesting an object) is still ongoing. Re. the investigation of referential communication in adults, we have observed that adults use color adjectives in situation where this is most efficient, and that efficiency is tied with incrementality. That is, adjective position plays a role in the production of color adjectives (e.g., there is a difference between pre-nominal adjectives, as in English, "the blue star" and post-nominal adjectives, as in Spanish, "la estrella azul"). So far our results have supported the hypothesis that adults use adjectival modification when this is efficient for coordination. The investigation of attentional processes in Theory of Mind task has revealed clear results showing that 3-year-old children get easily distracted in standard false-belief tasks (e.g., when hearing the name of the target object), whereas 5-year-olds are able to stay focused in the narrative. This is the first study that uses continuous eye-tracking measures in a standard false-belief task. The studies from 2017-2018 have revealed clear differences across languages, supporting the hypothesis that referential communication maximizes efficiency. Developmental studies have also shown important improvements during primary school, going from highly inefficient communication to adult levels of efficiency between ages 3 and 5. During the summer of 2018, we have also tested 100 younger and older adults, showing how referential communication decreases in efficiency with memory decay. The studies from 2018-2019 have revealed that older adults with good attention skills are efficient in their use of color adjectives. Analyses of verbal fluency in younger and older adults is still ongoing. Data collection for two developmental cross-linguistic studies is also ongoing: we are testing 5- and 7-year-old children and adult controls in Hindi, English, Mandinka, Polish and Spanish.

This research project aimed to investigate the development of referential communication across the lifespan, and its connection to Theory of Mind and Executive Function. A total of 16 articles have already been published, 5 are under review and 11 are in preparation. These papers have been published (or will be submitted) to peer-reviewed journals of international standing. We therefore expect that they will have high impact on several research fields, such as language, developmental psychology and aging. Our findings have applicability on education (both with neurotypical and clinical populations, such as ASD children) and training programs against cognitive decline. In addition, the two cognitive models of communication that I helped develop during my research stay at MIT have direct applications for Artificial Intelligence. Overall, the outcomes and impacts of this research project not only meet what was proposed in the grant application, but go beyond our initial expectations.

Reference is probably the most common phenomenon in human communication. From infants' early pointing gestures to the formulation of complex referential expressions (e.g., 'the large cookie jar on the top shelf'), speakers must develop linguistic and cogn itive abilities that allow them to refer to the world around them in effective ways. The focus of this research project is the development of those pragmatic abilities that make for effective referential communication. A key issue for pragmatic models of referential communication is the degree of informativeness of a given referential expression. In theory, speakers should not specify more information than is necessary to secure unique reference. Thus, in a situation where there is only one cookie jar, a sking for 'the cookie jar' should be enough for the hearer to identify the object. However, it has been repeatedly shown in psycholinguistic studies that adults tend to produce over-informative referential expressions, especially with colour adjectives (e .g., 'Could you bring me the red cookie jar over there?'). Our theoretical hypothesis is that such over-informative uses may be efficient in object requests, rather than violating pragmatic constraints on informativeness. The project will investigate two factors that may contribute to the effectiveness of referential communication: linguistic factors (e.g., whether adjectives are pre-nominal or post-nominal) and cognitive factors (e.g., whether memory capacity correlates with effective referential commun ication). Moreover, the project will investigate the development of effective referential abilities across the life span (from primary school to old age). For this purpose, we will use interactive tasks with pairs of participants who will have to jointly arrange various objects while we record their language production and eye movements. Overall, this project will help us determine what is effective in referential communication and how effectiveness develops.