**3. Results**

## *3.1. Summary of Participant Characteristics, Communication Acitvities, and AAC Use*

The participant characteristics are demonstrated in Table 3. The included children/ youths aged from four to 19 years old (mean age: 11 years; gender female: male 5:1). All of them had severe motor impairments as level II-V in GMFCS and IV-V in MACS, with a diagnosis of cerebral palsy, Rett syndrome, or high spinal cord injury. Most of them except Molly had cognitive impairments based on medical records. Three children/youths (Laura, Peter, and Sarah) had visual impairments, with strabismus or refractive errors such as astigmatism and myopia. Their eye control skills to interact with computers showed varied abilities on accuracy (22–100%) and speed for target selection (3.42–18.25 s). Considering communication abilities, most children used unconventional communication predominantly to refuse, request, or socialize by means of facial expressions, gestures, or vocalization. They also showed varied emerging skills in using concrete symbols and conventional communication skills such as eye-pointing for expression, except for Molly, who had higher symbol-communication skills. The communication partners included three teachers, two mothers, and one occupational therapist.



Note. GMFCS = Gross Motor Function Classification System, MACS = Manual Ability Classification System, OT = occupational therapist.

As shown in Table 4, the communication activities included unstructured play activities and mealtime and structured learning tasks (e.g., letters) in school, home or hospital contexts. The children/youths used the Tobii I-series or PCEye Mini [39] as eye-gaze devices and used Communicator 5 [39], Grid 3 [40], or Communicator with WordPower [39] as AAC software in the computers. In the NEGAT condition, they were accessed to a communication board, eye-gaze frame, or iPad with different types of AAC symbols. The numbers of symbols in the AAC system varied among the children/youths, from 3 to 50 symbols per page in EGAT and from 4 to 48 symbols per page in low-tech AAC, depending on their eye-control skills and symbol-communication abilities (Table 4).


**Table 4.** Video content and use of EGAT and low-tech AAC.

Note. NEGAT = Non-EGAT, PCS = Picture Communication Symbols. <sup>1</sup> PCS [39], SymbolStix [39,40], and Widgit symbols [40] are different symbol sets with colored images. Little step-by step [41] is a speech-generating device to provide sequential messages with voice output. Sono Flex [39] is a communication app with about 6000 symbols in standard version. <sup>2</sup> Low tech devices received but not used in the video.

*3.2. Group Results: Molar Level Analysis*

Group results are presented in Table 5.

**Table 5.** Mean rate per minute (RPM) and mean proportion of turns, moves and communicative functions in the EGAT and NEGAT conditions.


RPM = rate per minute. Two-way ANOVA and Bonferroni post hoc analysis to compare the differences of communicative turns in the EGAT and the NEGAT conditions between two groups. Parametric paired t-tests to compare the differences of moves and communicative functions between two conditions in each group. \* *p* < 0.05, † *p* < 0.1.
