Table 1.
Participant information and descriptive statistics for experimental and observational tasks in Experiment 1 (speech vs. non-speech; top) and Experiment 2 (speech vs. monkey calls; bottom).
| Exp. 1: Speech vs. Non-Speech | |||||||
| SIBS-A | SIBS-TD | ||||||
| Parental information | N | M | SD | Sig | N | M | SD |
| Maternal Education | 38 | 7.1 | 1.5 | p = .06 | 59 | 7.7 | 0.9 |
| Household Income | 37 | 6.7 | 2.4 | ns | 59 | 7.3 | 2.3 |
| 9 months | |||||||
| Chronological age at testing | 38 | 9.3 | 0.5 | p = .05 | 60 | 9.1 | 0.6 |
| Speech Preference Index | 38 | 1.8 | 5.4 | ns | 60 | 1.4 | 5.2 |
| Pre-test | 38 | 17.1 | 10.6 | ns | 60 | 17.6 | 10.7 |
| Post-test | 38 | 15.7 | 11.0 | ns | 60 | 13.7 | 10.5 |
| AOSI Total Score | 39 | 6.7 | 4.1 | ns | 60 | 5.6 | 3.4 |
| AOSI Total Markers | 39 | 4.3 | 2.0 | ns | 60 | 3.7 | 2.0 |
| 12 months | |||||||
| Chronological age at testing | 37 | 12.4 | 0.4 | p = .06 | 57 | 12.6 | 0.5 |
| MB-CDI Words Understood | 36 | 39.3 | 31.7 | ns | 52 | 31.3 | 25.5 |
| MB-CDI Words Produced | 36 | 49.3 | 19.4 | p = .06 | 52 | 45.1 | 18.2 |
| AOSI Total Score | 37 | 6.0 | 4.6 | p = .06 | 57 | 4.5 | 3.1 |
| AOSI Total Markers | 37 | 4.0 | 2.6 | ns | 57 | 3.1 | 1.9 |
| MSEL Gross Motor T | 38 | 43.7 | 11.7 | ns | 56 | 45.5 | 11.8 |
| MSEL Gross Motor Age Equivalent | 38 | 12.1 | 2.2 | ns | 56 | 12.5 | 2.0 |
| MSEL Fine Motor T | 38 | 56.2 | 10.9 | ns | 56 | 56.5 | 9.2 |
| MSEL Fine Motor Age Equivalent | 38 | 14.3 | 2.1 | ns | 56 | 14.6 | 1.9 |
| MSEL Visual Reception T | 38 | 49.8 | 8.0 | ns | 56 | 51.3 | 9.8 |
| MSEL Visual Reception Age Equivalent | 38 | 12.7 | 1.6 | ns | 56 | 13.2 | 2.2 |
| MSEL Receptive Language T | 36 | 38.4 | 6.6 | ns | 56 | 40.5 | 9.0 |
| MSEL Receptive Language Age Equivalent | 36 | 9.8 | 1.7 | ns | 56 | 10.4 | 2.1 |
| MSEL Expressive Language T | 38 | 51.8 | 9.7 | ns | 55 | 51.6 | 9.7 |
| MSEL Expressive Language Age Equivalent | 38 | 12.7 | 2.3 | ns | 55 | 12.9 | 2.2 |
| MSEL Early Learning Composite | 36 | 47.3 | 24.5 | ns | 55 | 49.9 | 26.3 |
| Exp. 2: Speech vs. Monkey Calls | |||||||
| SIBS-A | SIBS-TD | ||||||
| Parental information | N | M | SD | Sig | N | M | SD |
| Maternal Education | 46 | 7.1 | 1.4 | p = .03 | 53 | 7.7 | 0.9 |
| Household Income | 44 | 7.1 | 2.5 | ns | 53 | 7.8 | 2.2 |
| 9 months | |||||||
| Chronological age at testing | 46 | 9.3 | 0.5 | ns | 54 | 9.2 | 0.5 |
| Speech Preference Index | 46 | −0.8 | 7.0 | ns | 54 | −2.0 | 6.6 |
| Pre-test | 46 | 22.4 | 11.4 | ns | 54 | 19.5 | 11.6 |
| Post-test | 46 | 15.9 | 11.2 | ns | 54 | 15.9 | 10.2 |
| AOSI Total Score | 46 | 6.7 | 4.0 | p = .07 | 54 | 5.4 | 3.3 |
| AOSI Total Markers | 46 | 4.3 | 2.1 | p = .08 | 54 | 3.6 | 1.9 |
| 12 months | |||||||
| Chronological age at testing | 44 | 12.4 | 0.3 | p = .05 | 52 | 12.6 | 0.4 |
| MB-CDI Words Understood | 42 | 38.7 | 30.7 | ns | 47 | 37.9 | 27.9 |
| MB-CDI Words Produced | 42 | 49.2 | 19.5 | ns | 47 | 45.0 | 18.7 |
| AOSI Total Score | 44 | 5.9 | 4.4 | ns | 52 | 4.9 | 3.6 |
| AOSI Total Markers | 44 | 3.9 | 2.5 | ns | 52 | 3.2 | 2.2 |
| MSEL Gross Motor T | 45 | 43.5 | 11.0 | ns | 51 | 45.3 | 12.8 |
| MSEL Gross Motor Age Equivalent | 45 | 12.0 | 2.1 | ns | 51 | 12.5 | 2.2 |
| MSEL Fine Motor T | 45 | 55.6 | 10.1 | ns | 50 | 57.3 | 9.3 |
| MSEL Fine Motor Age Equivalent | 45 | 14.2 | 2.0 | ns | 50 | 14.6 | 1.8 |
| MSEL Visual Reception T | 45 | 49.9 | 7.5 | ns | 50 | 50.9 | 10.1 |
| MSEL Visual Reception Age Equivalent | 45 | 12.7 | 1.5 | ns | 50 | 13.1 | 2.2 |
| MSEL Receptive Language T | 43 | 39.4 | 8.6 | ns | 51 | 40.0 | 8.2 |
| MSEL Receptive Language Age Equivalent | 43 | 10.1 | 2.2 | ns | 51 | 10.4 | 2.1 |
| MSEL Expressive Language T | 45 | 52.6 | 10.6 | ns | 50 | 51.3 | 9.3 |
| MSEL Expressive Language Age Equivalent | 45 | 13.0 | 2.5 | ns | 50 | 12.9 | 2.3 |
| MSEL Early Learning Composite | 43 | 48.1 | 23.8 | ns | 49 | 49.5 | 26.0 |
| Exps. 1 & 2: Sample Overlap | |||||||
| SIBS-A | SIBS-TD | ||||||
| Parental information | N | M | SD | Sig | N | M | SD |
| Maternal Education | 37 | 7.1 | 1.5 | p = .03 | 42 | 7.7 | 0.9 |
| Household Income | 35 | 6.8 | 2.5 | ns | 42 | 7.6 | 2.3 |
| 9 months | |||||||
| Chronological age at testing | 37 | 9.3 | 0.5 | ns | 43 | 9.2 | 0.5 |
| AOSI Total Score | 37 | 6.9 | 4.2 | ns | 43 | 5.6 | 3.4 |
| AOSI Total Markers | 37 | 4.4 | 2.1 | ns | 43 | 3.7 | 2.0 |
| 12 months | |||||||
| Chronological age at testing | 36 | 12.4 | 0.4 | ns | 41 | 12.5 | 0.3 |
| MB-CDI Words Understood | 34 | 38.2 | 31.6 | ns | 37 | 34.2 | 26.8 |
| MB-CDI Words Produced | 34 | 48.5 | 18.7 | ns | 37 | 44.0 | 19.5 |
| AOSI Total Score | 35 | 6.1 | 4.7 | ns | 41 | 4.7 | 3.3 |
| AOSI Total Markers | 35 | 4.0 | 2.7 | ns | 41 | 3.2 | 2.1 |
| MSEL Gross Motor T | 36 | 42.8 | 11.4 | ns | 40 | 44.3 | 12.0 |
| MSEL Gross Motor Age Equivalent | 36 | 11.9 | 2.2 | ns | 40 | 12.3 | 2.0 |
| MSEL Fine Motor T | 36 | 55.5 | 10.7 | ns | 40 | 56.1 | 9.2 |
| MSEL Fine Motor Age Equivalent | 36 | 14.2 | 2.0 | ns | 40 | 14.4 | 1.8 |
| MSEL Visual Reception T | 36 | 49.9 | 7.8 | ns | 40 | 51.2 | 10.5 |
| MSEL Visual Reception Age Equivalent | 36 | 12.7 | 1.6 | ns | 40 | 13.1 | 2.3 |
| MSEL Receptive Language T | 34 | 37.7 | 6.1 | p = .08 | 40 | 40.8 | 8.4 |
| MSEL Receptive Language Age Equivalent | 34 | 9.6 | 1.6 | p = .05 | 40 | 10.5 | 2.0 |
| MSEL Expressive Language T | 36 | 51.3 | 9.7 | ns | 39 | 52.4 | 9.7 |
| MSEL Expressive Language Age Equivalent | 36 | 12.6 | 2.3 | ns | 39 | 13.1 | 2.3 |
| MSEL Early Learning Composite | 34 | 45.1 | 23.4 | ns | 39 | 50.6 | 27.0 |
Note. AOSI = Autism Observation Scale for Infants; MD-CDI = MacArthur Bates Communicative Development
Inventories; MSEL = Mullen Scales of Early Learning