*3.4. Individual Case Studies: Analysis at the Molecular Level*

One child typical of the group (Jane) and one atypical youth (Laura) who demonstrated the same diagnosis and severity of motor functions but varied in interactive patterns, were selected for further analysis. As shown in Table 6, Jane showed congruent results with most of the group patterns whereas Laura demonstrated several incongruent results.

As shown in Table 3, Jane had relatively high eye-gaze performance when using EGAT whereas Laura showed lower eye control skills (accuracy in Compass [32] = 100% vs. 36%, respectively). Jane had normal vision, and Laura had astigmatism but her performance on the Compass test was not impacted by her visual impairment, according to the report from the AT specialist. Both participants had communication abilities primarily in the level III unconventional communication [33]. However, Jane had more emerging abilities in conventional communication and concrete symbols (percent in the levels of Communication Matrix = 50%, 14.3%, respectively) compared to Laura (17.9%, 5%, respectively). Both participants used EGAT or low-tech AAC at the school or preschool.

**Figure 3.** Interrelationships between moves, communicative functions and modes in children and youths with complex needs: (**a**) Interrelationships between moves (initiation and response) and communicative functions in the eye-gaze assistive technology (EGAT) and the non eye-gaze assistive technology (NEGAT) conditions; (**b**,**c**) Interrelationships between communicative functions and modes in the EGAT (**b**) and the NEGAT (**c**) conditions.

Their film clips demonstrated different communicative interaction activities, play activities in Jane and school cognitive tasks in Laura (Table 4). In the structured school task, Laura's teacher dominated the interaction by taking many turns in both the EGAT and NEGAT conditions (rate per minute = 7.22, 7.50), focusing on instruction and questionanswer activity and requesting information, actions or clarification. Laura in turns showed quite few initiations (rate per minute = 0.37 and 0.29) but high rates of responses to answer the task (rater per minute= 1.85 and 2.82). Due to insufficient eye control skills at the early learning stage, she spent much effort operating/navigating the eye-gaze controlled computer (rate per minute = 2.04, the highest among all participants). She also showed a substantial frequency of unintelligible communicative functions particularly in the NEGAT condition (rate per min = 1.17), which might influence dyadic interaction in that the teacher would ask more questions or request clarification to receive a clear answer (see the Supplementary Materials Tables S1 and S2 for detailed data).

In summary, the individual case analysis indicated that, although Jane and Laura had similar health conditions, the form and purpose of the communication tasks in the environment (opportunities for children to take the initiative) seemed to be an essential factor for dyadic communicative interactions. Communication partners might demonstrate more directiveness in structured learning tasks than in play activities. In addition, insufficient eye control skills and communication abilities in pupils might contribute to the consequences of fewer initiations and limited information provision even when EGAT was provided.
