Testing Sensory and Multisensory Function in Children with Autism Spectrum Disorder

The overall goal of this procedure is to use psychophysical behavioral testing to characterize individual differences in temporal processing of auditory and visual stimuli in children with autism spectrum disorder and typical development. This is accomplished by first creating the necessary stimuli and verifying the timing precision of the stimulus presentation. The second step is to screen for participants that have normal hearing and vision.

Next, explain the instructions to the participant and have them complete each task. The final step is analyzing the data from each task and comparing differences in performance across all tasks. Ultimately, this behavioral battery is used to show how characterizing individual differences in temporal processing in children with autism can be used to assess sensory processing deficits, which may relate to higher order impairments in social communication.

Our world is made up of a variety of information from a number of different senses. As such, it's very important for us to understand how sensory information from the different senses is combined by the brain. Deficits in sensory processing are now recognized as a core symptom in autism spectrum disorder.

We can use this novel approach to help understand how children with autism perceive and integrate sensory information with the hope that we can use these methods to help shape treatment strategies. To begin generate two 16 millisecond sound files at 500 hertz and 1000 hertz. Use a sound pressure level meter to test the volume of each tone and verify that they are played at 60 decibels.

To create a visual stimulus, generate an image with a black background and a white ring centered on a fixation cross. Then have a native speaker sit in front of a camera and record each speech stimulus. To export the auditory component of each track, go to the export settings window of the video editing program.

Check the export audio box. Then click the format menu and select wave audio file. Click export to save the auditory component as a wave file.

To export the visual component of each track, go back to the export settings window and check the export video box. Then click the format menu and select H 2 64. Click export to save the visual component as a separate a VI file.

Finally, to create the McGurk stimulus, use the silent G video and the auditory component of the BA video. Import both files from the desktop. Next, drag the file GA V only dot AVI to the video source in the program sequence menu, and the BA A only dot wave file as the audio source in the program sequence menu.

Now, the participant will see the visual for ga, but hear the auditory stimulus. Ba Ba.Begin by attaching a chin rest to the participant table. Then use an oscilloscope, photovoltaic cell, and microphone to verify the stimulus, duration and stimuli onset asynchrony on the computer.

To do this, press pause on the oscilloscope to lock the screen. After the stimulus is played, a grid will overlay the screen of the oscilloscope, which acts as a scale bar. Verify the stimulus duration by looking at the length of the waveform from each channel compared to the scale bar on the oscilloscope.

The stimulus onset asynchronous are verified by looking at the distance between the two wave forms. Next, conduct a vision screen on each participant using a Snell and eye chart to ensure that all participants have 2040 vision or better record the lowest line that the participant can accurately report. Next, use an audio meter to test each participant's hearing at four different thresholds.

Instruct the participant to raise a hand each time they detect a tone. Once screening has been completed, escort the participant into a dimly lit sound controlled room where the experiment will take place. Sit the participant 60 centimeters away from the computer monitor to ensure that stimuli are the same intensity for each participant.

To begin the first test, instruct the participant to observe a flash and a beep. Explain to the participant that the task is to decide whether the flash and beep occur at the same time or at different times. Then instruct the participant to press one if the stimuli occur at the same time, and to press two if the stimuli occur at different times.

For the second test, begin by asking the participant to listen to two beeps presented at two different frequencies. Instruct the participant to press one on the number pad if the high tone is played first, or press two if the lower tone is played first. Next, ask the participant to observe two circles.

One will be above a central fixation cross, and the other below instruct the participant to press one on the number pad. If the top circle is presented first, and to press two, if the bottom circle is presented first, then ask the participant to observe a small flash on the screen and to listen to a single tone. Instruct the participant to press one on the number pad if the beep was presented first, and to press two if the flash was presented first.

For the third test, instruct the participant to observe the video in which a syllable is spoken BA, And then ask the participant to press the letter on the keyboard BA that corresponds to the syllable that they perceive from the video. For example, instruct them to press the letter B if they perceive the syllable, bah, or to press the letter G if they perceive GA.Representative. Results of the simultaneity judgment task are shown here.

There is a window of time in which visual auditory stimuli pairs can be presented with a delay and will be perceived as synchronous on a high proportion of trials. Furthermore, a subject with autism spectrum disorder has a wider temporal binding window than the subject with typical development. Here, the average accuracy of each of the temporal order judgment tasks at different delays is shown.

As the delay increases, the average accuracy increases across all conditions. The average accuracy for the audio visual stimuli is less than for the auditory or visual stimuli alone. Finally, representative data from the McGurk task with both subject groups are shown here.

Autism subjects shown in red perceived the fused audio visual syllable daon name significantly less than typical development subjects shown in black. Furthermore, as an example of the utility of this battery, the probability of the McGirk perception in individual subjects is plotted with their temporal binding window from the simultaneity judgment task. There was a negative correlation between McGirk perception and the temporal binding window, such that participants with low McGirk perception had a larger temporal binding window.

This test battery is very useful in understanding how sensory processing and sensory acuity differs in autism and how that relates to speech processing. Our ultimate goal is to take this task battery and use it in environment such as EEG and FMRI to understand a bit more about the brain bases of these phenomena. When employing this procedure, it's important to understand that the format of this task battery requires that all participants have the receptive language skills necessary to understand the verbal instructions for each task.

As such, this battery is currently only suitable for high functioning individuals with autism.