Exploration of closing-in behaviour in dementia, development and healthy adulthood
Closing-in Behaviour (CIB) is the tendency observed in copying tasks, both graphic and gestural, in which the copy is made inappropriately close to or on top of the model. It is classically considered as a manifestation of Constructional Apraxia (CA) and it is often observed in patients with dementia. CIB is not only a symptom of pathology, but it is also observed in children’s first attempts at graphic copying. However, CIB shows an inverse pattern in development and dementia: while its frequency increases in severe dementia, CIB progressively decreases with development. The cognitive origins of CIB are still unclear. Two main interpretations dominate CIB literature: the compensation and the attraction hypotheses. The first hypothesis interprets CIB as a strategy specific to copying tasks that the patient adopts to overcome visuospatial and working memory deficits. In contrast, the attraction hypothesis considers CIB as a primitive behaviour, not specific to copying, and characterized by the default tendency to perform an action toward the focus of attention. This thesis aimed to study the characteristics and the cognitive origins of CIB in dementia, development and healthy adulthood. It has three main sections. The first and second sections explore CIB in patients (with Alzheimer’s disease- AD and Frontotemporal dementia) and in pre-school children, using survey and experimental studies, to investigate if CIB might have common characteristics and cognitive substrates in these different populations. The results provided converging evidence for the similar nature of CIB in development and dementia. For instance, survey studies in patients with dementia (Chapter 3) and preschool children (Chapter 6) showed that performance in attentional tasks predicted the appearance of CIB. In a similar vein, experimental studies showed support for the attraction hypothesis of CIB in a single patient with AD (Chapter 4) and pre-school children (Chapter 7 and 8). These results were not, however, replicated in a larger cohort of patients with AD due to practical reasons (Chapter 5). The last section was devoted to modelling CIB in normal participants, using complex graphic copying (Chapter 9) and dual task paradigms (Chapter 10). The results showed further support for the attraction hypothesis of CIB and underlined the difficulties of eliciting this default bias in normal adults. To conclude, this thesis radically changes the classical consideration of CIB as a manifestation of CA and demonstrates that CIB is a general default tendency, not specific to copying tasks. This work indicates avenues for new studies, which might consider the possible expression and consequences of this behaviour in patients’ daily lives.