Do Lateral Glances Characterize a Specific Autistic Phenotype? Evidences From a Systematic Study

Background:   Some studies demonstrated that children with Autism Spectrum Disorders (ASDs) might show atypical visual exploration, like a preferential use of peripheral fields (Ritvo et al., 1986) or might look at the objects out of the corner of their eyes (Filipek et al.,1999). Recently, these atypical visual exploratory behaviours have been investigated by Mottron and colleagues (2007), who defined them as lateral glances towards a moving object, a manipulated object, or either towards the child’s own fingers. According to Mottron et al. (2007), these behaviors might be important distinctive signs of ASDs, although they are not specifically targeted in the standardized diagnostic tools but are merged with a miscellaneous of repetitive behaviors involving other perceptual modalities. For this reason, their frequency and their relationship with autism symptoms severity and cognitive development needs to be further investigated.

Objectives:  On the basis of these considerations, our study aimed to investigate the incidence of the lateral glances directed and not directed toward a specific target in a group of young children with autism, and to explore their relationship with symptoms severity and cognitive development.

Methods:   31 children with ASDs (26M and 5F; aver.chron.age=52months; 21 Autistics, 10 Pdd-Nos) participated at the study. The children were videotaped during twenty minutes of free play. The lateral glances (LG), defined as lateral movements of the eyes pupils in the corner of the eyes, were quantified thanks to a coding system specifically constructed by the authors, consisting in a list of all possible kind of lateral glances. In particular we defined 4 atypical visual behaviours: LG not directed to specific stimuli; LG not directed to specific stimuli associated to head rotation; LG directed to an object; LG directed to an object associated to head rotation. We divided the sample into two groups, using the mean score of total lateral glances as a cut-off, as follows: the first group included children with a high number of LG (above mean), the second one including children with a low number of LG (below mean). Then, we compared symptoms severity, assessed with the ADOS, and non-verbal IQ, measured with the Leiter-R scale, between the two groups.

Results:   The children with a high number of LG were more severe in ADOS total scores (ADOS High LG Group total scores mean=18.45, sd=2,77; ADOS Low LG Group total scores mean=15, sd=6,1; t=1,765; df=29; p=0.005). There were no differences between the two groups neither in non verbal intelligence nor in ADOS stereotypic behavior scores, suggesting that LG seems to be neither a sign of mental retardation nor a cue of stereotypic behavior classically coded in ASDs.

Conclusions:  These results seem to indicate that the lateral glances might be typical of a specific autistic phenotype. Therefore, these behaviors need to be further investigated as they could represent an early sign of ASDs, that could be used by paediatricians and parents in screening protocols and potentially included in standardized diagnostic tests.