Table 2 Summary of selected studies using instruments to promote communication and socialization among Down’s syndrome children

Deckers et al., 2017 [61]

The Netherlands

30 children with DS

DS (2 to 7) / 16 F and 14 M

Core vocabulary

15- to 20-min interactions

Three possible limitations of the present study require consideration. First, the sample size is relatively low at just 30 participants. The second limitation is the relatively small language samples collected of 100 words per child. The final limitation is the uneven distribution of words uttered in the three different settings.

Lorah, 2016 [38]

USA

7 students: 5 ASD, 2 DS

ASD (8 to 12) / 1 F and 4 M

DS (11 to 12) / 2 M

SGDs (Proloqu2Go ™) and PECS

10 weeks

The first was that baseline data were not collected. The second was the lack of inclusion of a generalization and maintenance measure within the research design. Finally, the inclusion of a standardized preference assessment such as Multiple Stimulus without Replacement would have enhanced the design.

Lanter et al., 2016 [59]

USA

1 child with DS

DS (7 years 8 months) / 1 M

Picture-based strategy

10 continuous sessions

Clinicians and educators should recognize that the methodology used in this case study was more reflective of that which might be conducted in a clinical or educational setting, as opposed to a rigorous research investigation. Although pre-experimental designs exist in the requesting literature using AAC modes of communication, these types of designs fail to provide ‘a convincing demonstration of experimental control’. Pre-experimental designs capture changes in behavior, which explains their frequent use in clinical or educational settings, but do not sufficiently rule out factors beyond the intervention that might explain those changes. Given that the child in this study failed to demonstrate requesting behaviors across multiple baseline sessions, it is unlikely that factors beyond the intervention were responsible for the communication changes observed.

González et al., 2015 [68]

Spain

9 children with DS

DS (9 to 29) / 7 F and 2 M

Interactive digital board prototype (whiteboard)

3 sessions lasting for 1 to 2 h

No limitations disclosed.

Logan et al., 2014 [57]

USA

1 child with DS

DS 1 year and 1 month / 1 F

Modified ride-on car

28 weeks

First, as with any single-subject research design, especially one involving an infant, it is difficult to conclude that changes were a result of the intervention and not simply maturation alone by the subject. It is important to remember that outcome changes are likely due to multiple factors. Second, this study does not meet every criterion of the single-case study research design. Several measures are used that are objective, standardized, reliable, and previously used [18] but are not widely available in a published format with large-scale reference data for comparison. Also, the PEDI was not administered after a reversal/retention phase. Third, it is possible that the extra attention, stimulation, and encouragement received during the intervention phase led to changes in the outcome measures that are unrelated to Natalie’s use of an ROC.

Wilkinson & Mcllvane, 2013 [52]

USA

12 participants with DS and 12 with ASD

DS (7 to 22)

ASD (7 to 22)

15 F and 9 M

PCS

2 sessions of 16 trials

Small sample, leading to difficulties in the distribution of subgroups for the instruments used.

Hu et al., 2013 [64]

USA

8 participants with DS and 5 neurotypical children

DS (10–28)

TD (10–13)

4 F and 9 M

Input techniques (keyboard, mouse, word prediction, and speech recognition)

2 sessions, taking into account a time of 45 min

The difficulty in accessing many participants, being aware of the severity of the disability, and comparing the performance of the participating groups. In their method, the task was observed by the researchers, and the participants might have felt uncomfortable or distracted. In addition, the time (software usability) was not completely controlled, so some participants had more time to learn and become familiar with the word prediction software. Another point to be considered is that participants are typically less motivated to perform tasks aimed at goals that are not of their choice compared to exploring tasks chosen by participants.

Brady et al., 2013 [37]

USA

93 children: 45 with ASD, 15 with DS, and 33 with other rare diseases

DS (3 to 5)

ASD (3 to 5)

Other (3 to 5)

20 F and 73 M

PECS,

SGDs, and Language Signals System

2 visits, T1 and T2

120 min for each child in T1 and again in T2, 12 months later

Did not record systematically the number of words available for each child through the AAC. Nevertheless, indicative systems such as group size, type of AAC, and language facilitator’s strategies in the classroom were not analyzed. These factors significantly affected the results for acquiring vocabulary, and therefore it was difficult to interpret the longitudinal effects on the instruction variables.

Barker et al., 2013 [36]

USA

83 children: 43 with ASD, 11 with DS, 3 with global development delay, 1 with spina bifida, 4 with CP, 13 with other genetic syndromes, 1 with traumatic brain injury, and 7 with unknown etiology.

DS (3 to 5)

ASD (3 to 5)

Global development delay (3 to 5)

Spina bifida (3 to 5)

Cp (3 to 5)

Other genetic syndromes (3 to 5)

Traumatic brain injury (3 to 5)

Unknown etiology

(3 to 5)

17 F and 66 M

PECS and SGDs

2 years

Did not consider the cognitive level of children, preventing comparative data reliability.

Van Der Meer et al., 2012 [35]

New Zealand

4 children: 1 with ASD, 1 with MSDD, 1 with DS, and 1 with congenital myotonic dystrophy and autistic-like behaviors.

DS (7) / 1 M

ASD (10) / 1 M

MSSD (5) / 1 M

Congenital myotonic dystrophy (5) / 1 M

SGDs and MAKATON

2 to 4 sessions, 3 to 4 days per week, lasting about 5 min and 10 trials (intervention) and 1 to 6 months’ follow-up

A short intervention time was used, hindering more robust data analysis.

Allsop et al., 2011 [55]

United Kingdom

257 children: 11 CP, 7 varying levels of deafness, 2 global developmental delay, and 1 DS

9 years and 8 months SD = 1.51, age range 4–12 years of age / 134 F and 123 M

Web-based survey (joystick)

3 trials

A limiting factor for a small number of the children with disabilities was language comprehension. The children who participated with genetic disorders such as DS or global learning delay often had an SA in place because of other language comprehension difficulties that occurred in their day-to-day education.

Wilkinson et al., 2008 [51]

USA

26 children: 16 with TD and 10 with DS

DS (11) / 7 F and 3 M

TD (3 to 4) / 6 F and 10 M

PCS

Training – 6 sessions; Evaluation – 2 blocks, with 12 experimental stimuli each

Error in recording incorrect stimuli.

Foreman & Crews, 1998 [8]

Australia

19 children with DS

DS (2 to 4) / 8 F and 11 M

MAKATON and COMPIC

4 days

Disclosed no limitations