Impaired identification of impoverished animate but not inanimate objects in adults with high-functioning autism spectrum disorder

The ability to identify animate and inanimate objects from impoverished images was investigated in adults with high-functioning autism spectrum disorder (HFA) and in matched typically developed (TD) adults, using a newly developed task. Consecutive frames were presented containing Gabor elements that slightly changed orientation from one frame to the next. For a subset of elements, the changes were such that these elements gradually formed the outline of an object. Elements enclosed within the object's outline gradually adopted one and the same orientation, outside elements adopted random orientations. The subjective experience was that of an object appearing out of a fog. The HFA group required significantly more frames to identify the impoverished objects than the TD group. Crucially, this difference depended on the nature of the objects: the HFA group required significantly more frames to identify animate objects, but with respect to the identification of inanimate objects the groups did not differ. The groups also did not differ with respect to the number and type of incorrect guesses they made. The results suggest a specific impairment in individuals with HFA in identifying animate objects. A number of possible explanations are discussed

Decomposition of a curve into arcs and line segments based on dominant point detection

International audienceA new solution is proposed to decompose a curve into arcs and straight line segments in $O(n\log n)$ time. It is a combined solution based on arc detection \cite{Nguyen10a_} and dominant point detection \cite{Nguyen10f} to strengthen the quality of the segmentation results. Experimental results show the fastness of the proposed method

Décomposition d'une courbe discrète en arcs de cercle et segments de droite

Session "Posters"National audienceUne nouvelle solution est proposée afin de décomposer une courbe en arcs et segments de droite en temps $O(n\log n)$. Il s'agit d'une combinaison entre une technique de segmentation en arcs et une technique de détection de points dominants pour renforcer la qualité des résultats obtenus. Elle est basée sur la notion de point isolé d'une courbe de points centraux dans espace particulier, dit espace des tangentes [Latecki00]. Un processus linéaire de balayage, appliqué pour détecter des points isolés, permet d'obtenir une représentation d'une courbe par des arcs de cercle et des segments de droite. De plus, la méthode proposée peut être combinée avec une technique non-paramétrique de polygonalisation afin de traiter des courbes bruitées sans utiliser des paramètres. Les résultats expérimentaux démontrent la robustesse de la méthode proposé

(Re-)conceptualisation in autism spectrum disorders

Background: Individuals with Autism Spectrum Disorder (ASD) have been shown to be compromised in cognitive flexibility and attentional switching. However, most studies that examine these executive functions did not distinguish between the ability to form new concepts and the ability to switch between concepts. Very few attempts have been made to disassociate them as separate abilities, or investigate whether the animate or inanimate nature of the concepts/objects affects these abilities. Further, very few switching tasks have investigated the autistic spectrum as a whole, with most studies focusing on severely autistic individuals.Aims: The aim of this thesis was to explore individual limitations in the perceptual-cognitive abilities of forming concepts (conceptualisation) and of switching between concepts (reconceptualisation) in individuals with varying degrees of ASD and in typically-developed (TD) individuals. Further aims were: (i) Examine whether the animate or inanimate nature of the concepts affect the (re-)conceptualisation abilities, and whether this effect varies along the autism spectrum. (ii) Examine the impact of the ‘salience of physical reality’ on the (re-)conceptualisation abilities. (iii) Examine whether there is a continuum in concept forming and/or switching underlying the entire autism spectrum, extending into the TD population.Methods: The basic experimental paradigm involved recognition of ambiguous and impoverished objects. Distinct animate and/or inanimate objects were morphed into each other, resulting in a sequence of interpolations with decreasing proportions of one object and increasing proportions of the other object. Participants had to identify the newly emerging object. There were two distinct versions: the Conceptualisation Task, in which participants had to form a new concept from ‘scratch’, and the Reconceptualisation Task, in which an existing concept had to be traded in for a new concept.Participants: Three different clinical groups were tested: adults with Asperger’s Syndrome (AS), children with AS, and children with autism. Each group and their control group, did not differ significantly in terms of age, sex or cognitive ability. In addition, on the basis of their score on the Autism Quotient (AQ), approximately the top and bottom 20% of the TD individuals were allocated to either a low or high AQ group.Experiments: Four new experimental paradigms were employed: (Re-)Conceptualisation Silhouette Task (see Chapters 2 and 3), (Re-)conceptualisation Gabor Task (see Chapter 4), Delis-Kaplan Executive Functioning System (D-KEFS) Sorting Task with a unique added ‘No Shuffle’ condition, where the cards were not shuffled after each correct sort (see Chapter 5) and an Object-Ratio Task (see Chapter 7). In addition, the performance of the participant groups on these new tasks was compared with their performance on existing concept-switching tasks that are part of the D-KEFS: the Trail Making Task and the Twenty Questions Task (see Chapter 6).Results: In both the Silhouette and Gabor tasks, the ASD groups were significantly impaired in identifying concepts compared to TD groups, in both the conceptualisation and the reconceptualisation conditions. However, the deficit was largest when they first had to disengage attention (reconceptualisation), and when the object was animate. The autism group performed worse than the AS group, but only with respect to animate objects. Furthermore, when the start-object remained physically present (Gabor Tasks), or when the correctly made sort was not shuffled, but remained physically present until a new sort was made (Card Sorting Task), the ASD groups were even more impaired. Quite strikingly, this impairment specifically pertained to animate objects. In the TD population, differences were found between those with low and those with high AQ scores. In terms of performance on the (Re-)Conceptualisation Tasks, the high AQ group occupied a position in between the low AQ and AS groups.Conclusions: Overall, the studies suggest that individuals with ASD are impaired in forming new concepts, especially when they first have to disengage their attention from a previously identified concept, and when the concept is animate. This deficit also extends to the TD population (to those TD individuals with high AQ scores). The findings therefore support the notion of a concept forming and concept switching continuum, that is present not only in ASD, but also in the general population. The findings further suggest that individuals with ASD possess a processing deficit specifically for animate concepts/objects, which becomes worse with increasing ASD severity