Visual Orienting Among Persons with Autism Spectrum Disorders

Atypical attentional behaviour is emerging as a robust marker of ASD in children as young as 12 months in both retrospective (1, 2) and prospective longitudinal studies (3). Young children as well as high-functioning adults with ASD exhibit unusual looking behaviour not only to people but to objects as well (4), suggesting atypical looking behaviour is not strictly a social problem but rather a broader problem with the strategic control of visual attention. This atypical attentional behaviour could contribute to many impairments that are characteristic of ASD. For example, failure to attribute meaning to eye gaze as a cue to direct attention could lead to a failure to engage in joint attention, a social activity in which two people share an experience about a commonly attended object that is considered to be an important precursor to language acquisition (5, 6). An impairment of joint attention is thought to reflect social difficulties, however it may be one of many manifestations of impaired strategic control of visual attention (7, 8). Klin et al. (9) suggest that from a very young age children with ASD misdirect attention in their environment, which would consequently impede learning, as the acquisition of skills and knowledge depends on how well children pay attention to their environment (10). This impairment in strategic control over the orientation of visual attention compromises the ability of the child to selectively direct attention to pertinent and relevant locations in the visual field. Thus, we suggest that visual orienting is intact in ASD but that the control of it is impaired. This specific impairment is also supported by similar patterns of findings in visuomotor coordination. Visual Orienting Visual attention can be directed either by focusing the eyes, or foveating, on a specific location or by choosing to attend to a location in peripheral vision. One model of visual attention is based on the metaphor of a spotlight beam that is directed to a specific location, and events within the beam are detected with enhanced efficiency (11, 12). Within this context, Posner (11) introduced the notion of the orienting of attention in which the directing of attention to a given location facilitated detection of a target at that location, but impeded detection of a target at another location. Visual cues are used to direct attention to the cued location either overtly, with eye movements, or covertly, without eye movements (11). Cues that elicit shifts of attention automatically, or unconsciously, are considered to be exogenous, as the shift is in response to the physical properties of the stimulus. An example is a flash of light, which attracts attention to the location of the flash. Cues that elicit voluntary shifts of attention are endogenous as the shift is in response to the symbolism or meaning of the cue. An example is an arrow, which directs attention to a secondary location away from the actual arrow. Deficits in exogenous orienting would suggest a basic problem in attending, whereas deficits in endogenous orienting, with spared exogenous orienting, would suggest a problem in the control of attention (13).