Processing Slow and Fast Motion in Children With Autism Spectrum Conditions

Abstract

Consistent with the dorsal stream hypothesis, difficulties processing dynamic information have previously been reported in individuals with autism spectrum conditions (ASC). However, no research has systematically compared motion processing abilities for slow and fast speeds. Here, we measured speed discrimination thresholds and motion coherence thresholds in slow (1.5 deg/sec) and fast (6 deg/sec) speed conditions in children with an ASC aged 7 to 14 years, and age- and ability-matched typically developing children. Unexpectedly, children with ASC were as sensitive as typically developing children to differences in speed at both slow and fast reference speeds. Yet, elevated motion coherence thresholds were found in children with ASC, but in the slow stimulus speed condition only. Rather than having pervasive difficulties in motion processing, as predicted by the dorsal stream hypothesis, these results suggest that children with ASC have a selective difficulty in extracting coherent motion information specifically at slow speeds. Understanding the effects of stimulus parameters such as stimulus speed will be important for resolving discrepancies between previous studies examining motion coherence thresholds in ASC and also for refining theoretical models of altered autistic perception.

Brief Report: Coherent Motion Processing in Autism: Is Dot Lifetime an Important Parameter?

“…The motion coherence task was the same as that described by Manning et al (2013). A trial consisted of a pair of stimuli presented sequentially separated by a 500ms interstimulus interval in which the apertures and fixation point remained on the screen.…”

“…Next, eight practice trials were presented to participants, with decreasing levels of coherence. Visual and verbal feedback was provided (for further details, see Manning et al, 2013).…”

“…Next, thresholds were estimated using the QUEST method (Watson & Pelli, 1983), with two staircases of 32 trials running interleaved and an additional 16 catch trials of 95% coherence (see Manning et al, 2013). No feedback regarding performance was provided during these trials, although the experimenter provided general encouragement throughout.…”

“…Parents of typically developing children and children with autism completed the Social Communication Questionnaire (SCQ; Rutter et al, 2003) and children with autism were administered the Autism Diagnostic Observation Schedule (ADOS-G or ADOS-2; Lord et al, 1999; using the revised algorithm (Gotham et al, 2007;2008). All children with autism scored above threshold for an autism spectrum condition on at least one of these measures (Manning et al, 2013) 2 and all TD children scored below the cut-off for autism on the SCQ (< 15; Rutter et al, 2003). All children had normal or corrected-to-normal acuity, defined as a binocular acuity of 6/9 or better for children aged chronological age, t(60) = .39, p = .70 or non-verbal ability, t(60) = 1.26, p = .21.…”

“…A motion coherence task was presented to children with autism aged 7 to 13 years and TD children matched in age and non-verbal ability with two stimulus conditions, limited and unlimited lifetime. The motion coherence task was based on that used by Manning et al (2013) and stimuli moved at a slow speed (1.5°/s). Manning et al previously reported that children with autism had elevated thresholds in this task for slow-moving (1.5°/s) limited lifetime stimuli.…”