Table 1.
Participant characteristics.
| Characteristic | FXS n = 17 boys |
SLI n = 20 (13 boys, seven girls) |
TD n = 19 (9 boys, 10 girls) |
|||
|---|---|---|---|---|---|---|
| Mean | (SD) | Mean | (SD) | Mean | (SD) | |
| Chronological age (years) | 11.9 | (1.7) | 4.9 | (0.7) | 3.3 | (0.3) |
| Cognition (standard score) a | 47.9 | (7.4) | 111.0 | (16.1) | 118.5 | (13.9) |
| Mental age a | 5.3 | (0.7) | 5.3 | (1.1) | 4.3 | (0.7) |
| MLU | 3.8 | (1.1) | 4.0 | (0.7) | 3.9 | (0.8) |
| Receptive vocabulary (standard score) b | 59.5 | (15.5) | 95.8 | (11.2) | 113.7 | (10.9) |
| Receptive vocabulary (raw score) b | 100.7 | (23.5) | 73.5 | (20.4) | 64.5 | (13.0) |
| Third-person probe (% correct) c | 82.2 | (25.4) | 36.5 | (25.7) | 50.8 | (16.3) |
| Past tense probe (% correct) c | 63.7 | (24.8) | 28.0 | (20.1) | 46.9 | (17.5) |
| Be/do probe–be (% correct) c | 82.6 | (24.4) | 50.1 | (23.9) | 77.3 | (17.3) |
| Be/do probe–do (% correct) c | 42.8 | (34.2) | 14.2 | (19.3) | 44.1 | (32.0) |
| Child race | Frequency | |||||
| Caucasian | 15 | 15 | 18 | |||
| African American | 1 | 1 | 0 | |||
| More than one race | 1 | 4 | 1 | |||
Note. FXS = fragile X syndrome; SLI = specific language impairment; TD = typical development; MLU = mean length of utterance.
a
Leiter International Performance Scale–Revised (Roid & Miller, 1997) or Reynolds Intellectual Assessment Scale (Reynolds & Kamphaus, 2003).
b
Peabody Picture Vocabulary Test–Fourth Edition (Dunn & Dunn, 2007).
c
Test of Early Grammatical Impairment (Rice & Wexler, 2001) subtest percentage correct scores exclude items with unscorable responses and no response, according to the manual.