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Saturday, May 9, 2009
Northwest Hall (Chicago Hilton)
12:00 PM
Background: Infants who have siblings with an Autism Spectrum Disorder (ASD) are at greater risk for developing ASD than in the general population. Prospective studies of high-risk infants can thus reveal early risk markers for the development of ASD. Previous studies have suggested that poor performance on visual attention tasks may be a risk marker for ASD (e.g. Zwaigenbaum et al., 2005; Elsabbagh et al., 2007). However, little is known about how testing conditions affect this method of assessment. Examining how testing circumstances influence performance on early measures may help us interpret early assessments of infants at risk for ASD.
Objectives: To examine the influence of testing circumstances on performance on an attention task in infants with and without siblings with ASD.
Methods: Participants were 14 6-month-old infants with siblings with an ASD (sib group) and 13 6-month-old infants with no family history of ASD (control group). In addition to developmental and diagnostic testing, both groups participated in the “gap-overlap” task, where reaction time to shift fixation from a central to a peripheral stimulus was measured. This task involves three trial types: baseline (central stimulus disappears and peripheral stimulus appears simultaneously), gap (central stimulus disappears before peripheral stimulus appears), and overlap (central stimulus remains on screen with peripheral stimulus). Critically, the difference in latency to shift between baseline and overlap trials is thought to reflect the efficiency of attention disengagement.
The task was repeated twice with different stimulus sets. At Visit 1, the task was administered at the end of a lab visit (approximately 90 minutes after arrival); on Visit 2, the task was run at the beginning of the visit.
Results: Replicating previous work, reaction time was slower and more variable on overlap trials than baseline or gap trials in both the control and sib groups. Preliminary analyses indicate that when the gap-overlap task was administered after participation in other tasks, the sib group showed significantly greater difficulty in disengaging than the control group, as observed in a previous study (Elsabbagh et al., 2007). For both groups, there was variability in reaction times between Visit 1 and Visit 2.
Conclusions: Replicating previous work, infants with a sibling with ASD showed slower disengagement than the control group. Inspection of our data raises the possibility that there may be greater variability in the performance of the sib group than the control group across the two testing sessions. Variability in performance may be an important risk marker. Further analysis will increase group sizes to examine whether this finding will hold in a larger sample.
Objectives: To examine the influence of testing circumstances on performance on an attention task in infants with and without siblings with ASD.
Methods: Participants were 14 6-month-old infants with siblings with an ASD (sib group) and 13 6-month-old infants with no family history of ASD (control group). In addition to developmental and diagnostic testing, both groups participated in the “gap-overlap” task, where reaction time to shift fixation from a central to a peripheral stimulus was measured. This task involves three trial types: baseline (central stimulus disappears and peripheral stimulus appears simultaneously), gap (central stimulus disappears before peripheral stimulus appears), and overlap (central stimulus remains on screen with peripheral stimulus). Critically, the difference in latency to shift between baseline and overlap trials is thought to reflect the efficiency of attention disengagement.
The task was repeated twice with different stimulus sets. At Visit 1, the task was administered at the end of a lab visit (approximately 90 minutes after arrival); on Visit 2, the task was run at the beginning of the visit.
Results: Replicating previous work, reaction time was slower and more variable on overlap trials than baseline or gap trials in both the control and sib groups. Preliminary analyses indicate that when the gap-overlap task was administered after participation in other tasks, the sib group showed significantly greater difficulty in disengaging than the control group, as observed in a previous study (Elsabbagh et al., 2007). For both groups, there was variability in reaction times between Visit 1 and Visit 2.
Conclusions: Replicating previous work, infants with a sibling with ASD showed slower disengagement than the control group. Inspection of our data raises the possibility that there may be greater variability in the performance of the sib group than the control group across the two testing sessions. Variability in performance may be an important risk marker. Further analysis will increase group sizes to examine whether this finding will hold in a larger sample.