These method can help answer key questions in understanding the language abilities of children with autism, such as whether they can understand a sentence using both linguistic and non-linguistic information. The main advantages of this method are that it is sensitive to the time code of sentence comprehension, and it requires minimal task and communication demand. This method simply records eye movements as automatic responses to linguistic input without asking participants to provide conscious judgments about the input, thus significantly reducing the computational model of participants.
Begin by constructing test stimuli that consists of 12 visual target items, and two spoken sentences containing the morphological markers BA and BEI. Create a visual image from a template within the image editing software, in which each image contains two pictures. Double click the template to open it.
Adjust the width, height, resolution, and color depth from the pop-up menus. Enter the relevant parameters. Then, reverse the event roles of the two characters in the two pictures.
Click File Export. Next, set up the microphone and open the audio editing software to construct the spoken sentences. Select Record Mono Sound from the new menu.
Set the recording conditions by clicking the Sample rate option of 44, 100 Hertz. Click the Record button. Finally, record the spoken sentences by asking a native Beijing Mandarin speaker to produce the sentences in a child-directed manner.
Save the recordings by clicking Save. Begin by having the participant sit in front of the display monitor of the remote eye tracker. Set the distance between the participant's eyes and the monitor around 60 centimeters.
Perform the standard calibration and validation procedures by asking the participants to fixate on a grid of five fixation targets in random succession. Then, ask the participant to listen to the spoken sentences while they are viewing the pictures. Have one experimenter to monitor the participant on the computer, and one to stand behind the participant and gently rest their hands on the participant's shoulders to minimize the participant's sudden movements.
Next, have the participant complete the task to measure eye movements that arise as automatic responses to the linguistic input. After the task is complete, view the data and define two interest areas, BA target event area and BEI target event area, by selecting one of the interest area shape icons on the tool bar, and drawing a box around the region to be defined as an interest area. Save the interest area in the Interest Area set up folder.
Finally, choose the Interest Period Manager from the menu to set the time window to every 200 milliseconds for analysis. Use the same function to time lock the fixation proportions in the interest areas to the onset of the marker for each trial, and use the Interest Area Report function to export the raw data into an Excel file. Use the Excel functions to average the fixation proportions following the onset of the marker for each area.
Then, use the Excel functions to compute the fixation proportions in each time window of 200 milliseconds over a period of 5, 200 milliseconds from the onset of the marker for the two areas. Results indicate that the autism group displayed eye movement patterns similar to the age-matched TD group. Both groups exhibited more fixations on the BA target event when hearing BA then when hearing BEI, occurring after the onset of the object np and before the onset of the adverb.
To be specific, the event occurred in the TD group during the window between 1, 400 and 1, 600 milliseconds. Whereas, the effect occurred in the autism group during the window between 1, 800 and 2, 000 milliseconds. After its development, the paradigm has been successfully used to test typical developing children's language abilities.
Our lab has now extended the paradigm to the study of language comprehension abilities in pre-school children with autism. Keeping in mind that we're working with special populations, children with autism often exhibit various kinds of challenging behaviors or symptoms, in particular in unfamiliar environment, so extra care needs to be taken before and during the test. Prior to the experiment, it is important that the experimenters acclimate the participants to the experimental environment.
During the test, the experimenters may need to redirect the participants and prompt them to rearrange to the computer screen several times.
