An Experiment in Modelling Learning in Autism Using Self-Organizing Artificial Neural Networks

Autism is a developmental disorder with possibly multiple etiologies. Attention shift impairment and strong familiarity preference or negative response to novelty are prevalent in individuals with autism and researchers argue which one of these features is primary to other deficiencies in autism. Cortical feature maps make it possible to classify stimuli, such as phonemes of speech, disregarding incidental detail. Hierarchies of such maps are instrumental in creating abstract codes and representations of objects and events. It has been theorized that cortical feature maps in individuals with autism are inadequate for forming abstract codes and representations, which would explain the importance paid by autistic individuals to detail rather than salient features. Self-Organizing Maps (SOMs) are artificial neural networks (ANNs) which offer insights into the development of cortical feature maps. We model attention shift by presenting a SOM with stimuli from two sources in four different modes, namely: 1) novelty seeking (regarded as normal learning), 2) attention shift impairment (shifts are made with a low probability), 3) familiarity preference (shifts made with a lower probability to that source which is the less familiar to the SOM of the two sources) and 4) familiarity preference in conjunction with attention shift impairment. The resulting feature maps from learning with novelty seeking and with attention shift impairment are, perhaps surprisingly, much the same. In contrast, the resulting maps from learning with strong familiarity preference are adapted to one of the sources at the expense of the other and if one of the sources has a reduced set of stimuli the resulting maps are adapted to stimuli from that reduced source. When familiarity preference is less pronounced the resulting maps show great variation, from normal to fully restricted to one of the sources and always the reduced source if such a source is present. Such learning, in many different maps, would result in very uneven capacities, which is common in individuals with autism. Learning with attention shift impairment in conjunction with familiarity preference further reduces the probabilities for normal maps. Early intervention in the learning process, based on the observation of attention shift misses and implemented as an increased number of stimuli being presented to the SOM from the less familiar source, results in a significantly higher probability for the development of a normal map.