Figure : Age distribution of
autistic and non-autistic participants.
Apparatus and stimuli. The experiment was programmed and
conducted online using the Neurotask platform
(www.neurotask.com). Participants
completed the task using their own hardware. The stimuli were taken from
Hillock-Dun, Grantham, and Wallace (2016) and included videos of an
actress saying the syllable /ga/ with either the corresponding audio
(for congruent trials) or the audio of the same actress saying the
syllable /ba/ dubbed over the video (for incongruent trials). Stimulus
onset asynchrony (SOA) was either -500, -260, 0, 260 or 500 ms. Here,
negative signifies that audition was leading, and vice versa. All videos
lasted 2000 ms.
Procedure . Trials began with a black fixation cross in the center
of a white screen for 1000 ms. Subsequently, the video played for 2000
ms. After its conclusion, participants were prompted to make two
self-paced responses. First, they were asked whether they heard /ba/,
/da/, or /ga/ by pressing either the b, d, or g-key, respectively.
Second, they were asked whether the video and audio were synchronized or
not by pressing the 1 or 0-key, respectively. The following trial was
initiated as soon as the synchrony judgment was given. The two
congruency types and five SOAs produced a total of ten unique trial
types. After reading the written instructions and completing ten
practice trials (one of each stimulus type), participants completed ten
repetitions of each trial type, for a total of 100 experimental trials
in randomized order. The experiment lasted approximately 7 minutes and
was part of a larger battery of online tasks (not reported here). Figure
2 illustrates an example trial sequence.