Association between prenatal antibiotic exposure and autism spectrum disorder among term births: A population-based cohort study.

BACKGROUND: Prenatal antibiotic exposure induces changes in the maternal microbiome, which could influence the development of the infant's microbiome-gut-brain axis. OBJECTIVES: We assessed whether prenatal antibiotic exposure is associated with an increased risk of autism spectrum disorder (ASD) in offspring born at term. METHODS: This population-based retrospective cohort study included everyone who delivered a live singleton-term infant in British Columbia, Canada between April 2000 and December 2014. Exposure was defined as filling antibiotic prescriptions during pregnancy. The outcome was an ASD diagnosis from the British Columbia Autism Assessment Network, with a follow-up to December 2016. To examine the association among pregnant individuals treated for the same indication, we studied a sub-cohort diagnosed with urinary tract infections. Cox proportional hazards models were used to estimate unadjusted and adjusted hazard ratios (HR). The analysis was stratified by sex, trimester, cumulative duration of exposure, class of antibiotic, and mode of delivery. We ran a conditional logistic regression of discordant sibling pairs to control for unmeasured environmental and genetic confounding. RESULTS: Of the 569,953 children included in the cohort, 8729 were diagnosed with ASD (1.5%) and 169,922 were exposed to prenatal antibiotics (29.8%). Prenatal antibiotic exposure was associated with an increased risk of ASD (HR 1.10, 95% confidence interval [CI] 1.05, 1.15), particularly for exposure during the first and second trimesters (HR 1.11, 95% CI 1.04, 1.18 and HR 1.09, 95% CI 1.03, 1.16, respectively), and exposure lasting ≥15 days (HR 1.13, 95% CI 1.04, 1.23). No sex differences were observed. The association was attenuated in the sibling analysis (adjusted odds ratio 1.04, 95% CI 0.92, 1.17). CONCLUSIONS: Prenatal antibiotic exposure was associated with a small increase in the risk of ASD in offspring. Given the possibility of residual confounding, these results should not influence clinical decisions regarding antibiotic use during pregnancy.

Autism Risk and Perinatal Antibiotic Use.

OBJECTIVES: Antibiotics are commonly administered during labor and delivery, and research has suggested that fetal exposure to antibiotics can increase risk for autism spectrum disorder (ASD). We assessed whether antibiotic exposure during labor and delivery increased the risk of ASD in the offspring. METHODS: This retrospective cohort study included everyone who delivered a live singleton-term infant in British Columbia, Canada, between April 1, 2000, and December 31, 2014. This cohort included 569 953 deliveries. To examine the association among pregnant individuals being treated for the same indication, we studied a subcohort of those who tested positive for group B Streptococcus. Cox proportional hazards models were used to estimate unadjusted and adjusted hazard ratios in both cohorts. A sensitivity analysis was conducted using length of first stage of labor as a proxy measure for dose to assess for a dose-response relationship. RESULTS: In this population-based study, antibiotic use during labor and delivery was not associated with an increased risk of ASD in offspring. The unadjusted and adjusted hazard ratios were 1.29 (95% confidence interval, 1.24-1.35) and 0.99 (0.94-1.04), respectively; and 1.07 (0.90-1.27) and 0.88 (0.74-1.05), respectively, in the group B Streptococcus-positive cohort. We observed no substantial difference in the association between antibiotic exposure and ASD depending on length of the first stage of labor. CONCLUSIONS: Our findings suggest that concern for ASD should not factor into the clinical decision on whether to administer antibiotics during labor and delivery. Future research is needed to examine longer durations of prenatal antibiotic exposure.

The association between prenatal greenspace exposure and Autism spectrum disorder, and the potentially mediating role of air pollution reduction: A population-based birth cohort study.

BACKGROUND: Autism spectrum disorder (ASD) incidence has increased in past decades. ASD etiology remains inconclusive, but research suggests genetic, epigenetic, and environmental contributing factors and likely prenatal origins. Few studies have examined modifiable environmental risk factors for ASD, and far fewer have examined protective exposures. Greenspace has been associated with positive child development, but very limited greenspace research has examined ASD risk or prenatal exposures. Only one ecological study in 2017 has evaluated the association between greenspace and ASD, observing protective benefits. Greenspace may have direct effects on ASD risk and indirect effects by reducing air pollution exposure, a growing suspected ASD risk factor. OBJECTIVES: To measure the association between prenatal greenspace exposure and ASD risk and examine if reduced air pollution levels in areas of higher greenspace mediate this association. METHODS: We linked a population-based birth cohort of all deliveries in Metro Vancouver, Canada, from 2004 to 2009, with follow-up to 2014. Diagnoses were based on Autism Diagnostic Observation Schedule and Autism Diagnostic Interview-Revised instruments. Greenspace was quantified as the average of the annual mean Normalized Difference Vegetation Index (NDVI) within a 250 m buffer of a residential postal code. Air pollutant exposures-particulate matter with a diameter less than 2.5 µm (PM2.5), nitric oxide (NO), and nitrogen dioxide (NO2)-were derived from previously developed and temporally adjusted land use regression models. We estimated air pollutant exposures as the mean concentration per month during pregnancy. We calculated odds ratios (ORs) using logistic regression per NDVI interquartile range (IQR) increase, adjusting for child sex, birth month and year, maternal age and birthplace, and neighborhood-level urbanicity and income. To estimate the health impact of greenspace on ASD at the population level, we used the logistic regression model and marginal standardization to derive risk differences (RDs). Lastly, to quantify the mediating effect of greenspace on ASD risk through air pollution reduction, we used marginal structural models and a potential outcomes framework to calculate marginal risk differences (RDs) to decompose the total effect of greenspace on ASD into natural direct and indirect effects. RESULTS: Of 129,222 births, 1,921 (1.5 %) children were diagnosed with ASD. The adjusted OR for ASD per NDVI IQR (0.12) increase was 0.96 (95 % CI: 0.90, 1.02) in 250 m buffer zones and 0.94 (95 % CI: 0.89, 1.00) in 100 m buffer zones. On the additive scale, the adjusted RDs were null. Natural direct, natural indirect, and total effect RDs were null for PM2.5, NO, and NO2 mediation models. CONCLUSION: Prenatal greenspace exposure was associated with reduced odds of ASD, but in the additive scale, this effect was null at the population level. No mediating effect was observed through reduced air pollution, suggesting that air pollution may act as a confounder rather than as a mediator.

Appraising the need for audiological assessment before autism spectrum disorder referral.

Objectives: Mandatory audiological testing before autism spectrum disorder (ASD) assessment is common practice. Hearing impairment (HI) in the general paediatric population is estimated at 3%; however, hearing impairment prevalence among children with ASD is poorly established. Our objective was to determine which children referred for ASD assessment require preliminary audiological assessment. Methods: Retrospective chart review of children (n=4,173; 0 to 19 years) referred to British Columbia's Autism Assessment Network (2010 to 2014). We analyzed HI rate, risk factors, and timing of HI diagnosis relative to ASD referral. Results: ASD was diagnosed in 53.4%. HI rates among ASD referrals was 3.3% and not significantly higher in children with ASD (ASD+; 3.5%) versus No-ASD (3.0%). No significant differences in HI severity or type were found, but more ASD+ females (5.5%) than ASD+ males (3.1%) had HI (P<0.05). Six HI risk factors were significant (problems with intellect, language, vision/eye, ear, genetic abnormalities, and prematurity) and HI was associated with more risk factors (P<0.01). Only 12 children (8.9%) were diagnosed with HI after ASD referral; all males 6 years or younger and only one had no risk factors. ASD+ children with HI were older at ASD referral than No-ASD (P<0.05). Conclusions: Children with ASD have similar hearing impairment rates to those without ASD. HI may delay referral for ASD assessment. As most children were diagnosed with HI before ASD referral or had at least one risk factor, we suggest that routine testing for HI among ASD referrals should only be required for children with risk factors.

Association of Epidural Analgesia During Labor and Delivery With Autism Spectrum Disorder in Offspring.

Importance: Evidence from studies investigating the association of epidural analgesia use during labor and delivery with risk of autism spectrum disorder (ASD) in offspring is conflicting. Objective: To assess the association of maternal use of epidural analgesia during labor and delivery with ASD in offspring using a large population-based data set with clinical data on ASD case status. Design, Setting, and Participants: This population-based retrospective cohort study included term singleton children born in British Columbia, Canada, between April 1, 2000, and December 31, 2014. Stillbirths and cesarean deliveries were excluded. Clinical ASD diagnostic data were obtained from the British Columbia Autism Assessment Network and the British Columbia Ministry of Education. All children were followed up until clinical diagnosis of ASD, death, or the study end date of December 31, 2016. Exposures: Use of epidural analgesia during labor and delivery. Main Outcomes and Measures: A clinical diagnosis of ASD made by pediatricians, psychiatrists, and psychologists with specialty training to assess ASD. Cox proportional hazards models were used to estimate the hazard ratio of epidural analgesia use and ASD. Models were adjusted for maternal sociodemographics; maternal conditions during pregnancy; labor, delivery, and antenatal care characteristics; infant sex; gestational age; and status of small or large for gestational age. A conditional logistic regression model matching women with 2 births or more and discordance in ASD status of the offspring also was performed. Results: Of the 388 254 children included in the cohort (49.8% female; mean gestational age, 39.2 [SD, 1.2] weeks; mean follow-up, 9.05 [SD, 4.3] years), 5192 were diagnosed with ASD (1.34%) and 111 480 (28.7%) were exposed to epidural analgesia. A diagnosis of ASD was made for 1710 children (1.53%) among the 111 480 deliveries exposed to epidural analgesia (94 157 women) vs a diagnosis of ASD in 3482 children (1.26%) among the 276 774 deliveries not exposed to epidural analgesia (192 510 women) (absolute risk difference, 0.28% [95% CI, 0.19%-0.36%]). The unadjusted hazard ratio was 1.32 (95% CI, 1.24-1.40) and the fully adjusted hazard ratio was 1.09 (95% CI, 1.00-1.15). There was no statistically significant association of epidural analgesia use during labor and delivery with ASD in the within-woman matched conditional logistic regression (839/1659 [50.6%] in the exposed group vs 1905/4587 [41.5%] in the unexposed group; fully adjusted hazard ratio, 1.07 [95% CI, 0.87-1.30]). Conclusions and Relevance: In this population-based study, maternal epidural analgesia use during labor and delivery was associated with a small increase in the risk of autism spectrum disorder in offspring that met the threshold for statistical significance. However, given the likelihood of residual confounding that may account for the results, these findings do not provide strong supporting evidence for this association.

Effects of maternal depression and prenatal SSRI exposure on executive functions and susceptibility to household chaos in 6-year-old children: prospective cohort study.

BACKGROUND: Maternal depressed mood during pregnancy may shape a child's adaptation to their environment and engagement in goal-directed behaviour such as executive functions. Whether everyday household context also alters executive functions in children with prenatal selective serotonin reuptake inhibitor (SSRI) antidepressant exposure remains to be determined. AIMS: To examine the impact of prenatal depressed maternal mood and SSRI exposure on child executive functions and to determine whether these exposures shape a susceptibility to household chaos. METHOD: A prospective cohort study of mothers and their children (118 mother-children dyads (47 SSRI-exposed, 71 non-exposed)) followed from the second trimester to 6 years. Regression models examined relationships between maternal depressed mood and household chaos on maternal report of child executive functions. Competitive-confirmatory regression models examined whether children were susceptible to household chaos or were positively influenced by less chaos. RESULTS: Prenatal SSRI exposure, third-trimester maternal depressed mood and household chaos in a three-way interaction were associated with executive functions within a model of differential susceptibility. When household chaos was low, children of non-prenatally depressed mothers had better executive function than children of prenatally depressed mothers, regardless of whether the mothers were SSRI-treated. However, when household chaos was high, SSRI-exposed children of mothers who were not depressed during pregnancy had poorer executive functions at 6 years of age compared with SSRI-exposed children whose mothers were symptomatic during pregnancy. CONCLUSIONS: The impact of household chaos depended on whether mothers were prenatally depressed and whether mothers were SSRI-treated.

Identification of Pediatric Autism Spectrum Disorder Cases Using Health Administrative Data.

Administrative data are frequently used to identify Autism Spectrum Disorder (ASD) cases in epidemiological studies. However, validation studies on this mode of case ascertainment have lacked access to high-quality clinical diagnostic data and have not followed published reporting guidelines. We report on the diagnostic accuracy of using readily available health administrative data for pediatric ASD case ascertainment. The validation cohort included almost all the ASD-positive children born in British Columbia, Canada from April 1, 2000 to December 31, 2009 and consisted of 8,670 children in total. 4,079 ASD-positive and 2,787 ASD-negative children were identified using Autism Diagnostic Observation Schedule (ADOS) and Autism Diagnostic Interview-Revised (ADI-R) assessments done through the British Columbia Autism Assessment Network (BCAAN). An additional 1,804 ADOS/ADI-R assessed ASD-positive children were identified using Ministry of Education records. This prospectively collected clinical data (the diagnostic gold standard) was then linked to each child's physician billing and hospital discharge data. The diagnostic accuracy of 11 algorithms that used the administrative data to assign ASD case status was assessed. For all algorithms, high positive predictive values (PPVs) were observed alongside low values for other measures of diagnostic accuracy illustrating that PPVs alone are not an adequate measure of diagnostic accuracy. We show that British Columbia's health administrative data cannot reliably be used to discriminate between children with ASD and children with other developmental disorders. Utilizing these data may result in misclassification bias. Methodologically sound, region-specific validation studies are needed to support the use of administrative data for ASD case ascertainment. Autism Res 2020, 13: 456-463. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Health administrative data are frequently used to identify Autism Spectrum Disorder (ASD) cases for research purposes. However, previous validation studies on this sort of case identification have lacked access to high-quality clinical diagnostic data and have not followed published reporting guidelines. We show that British Columbia's health administrative data cannot reliably be used to discriminate between children with ASD and children with other developmental disorders.

Association of Prenatal Exposure to Air Pollution With Autism Spectrum Disorder.

Importance: The etiology of autism spectrum disorder (ASD) is poorly understood, but prior studies suggest associations with airborne pollutants. Objective: To evaluate the association between prenatal exposures to airborne pollutants and ASD in a large population-based cohort. Design, Setting, and Participants: This population-based cohort encompassed nearly all births in Metro Vancouver, British Columbia, Canada, from 2004 through 2009, with follow-up through 2014. Children were diagnosed with ASD using a standardized assessment with the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Monthly mean exposures to particulate matter with a diameter less than 2.5 µm (PM2.5), nitric oxide (NO), and nitrogen dioxide (NO2) at the maternal residence during pregnancy were estimated with temporally adjusted, high-resolution land use regression models. The association between prenatal air pollution exposures and the odds of developing ASD was evaluated using logistic regression adjusted for child sex, birth month, birth year, maternal age, maternal birthplace, and neighborhood-level urbanicity and income band. Data analysis occurred from June 2016 to May 2018. Exposures: Mean monthly concentrations of ambient PM2.5, NO, and NO2 at the maternal residence during pregnancy, calculated retrospectively using temporally adjusted, high-resolution land use regression models. Main Outcomes and Measures: Autism spectrum disorder diagnoses based on standardized assessment of the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. The hypothesis being tested was formulated during data collection. Results: In a cohort of 132 256 births, 1307 children (1.0%) were diagnosed with ASD by the age of 5 years. The final sample size for the PM2.5-adjusted model was 129 439 children, and for NO and NO2, it was 129 436 children; of these, 1276 (1.0%) were diagnosed with ASD. Adjusted odds ratios for ASD per interquartile range (IQR) were not significant for exposure to PM2.5 during pregnancy (1.04 [95% CI, 0.98-1.10] per 1.5 µg/m3 increase [IQR] in PM2.5) or NO2 (1.06 [95% CI, 0.99-1.12] per 4.8 ppb [IQR] increase in NO2) but the odds ratio was significant for NO (1.07 [95% CI, 1.01-1.13] per 10.7 ppb [IQR] increase in NO). Odds ratios for male children were 1.04 (95% CI, 0.98-1.10) for PM2.5; 1.09 (95% CI, 1.02-1.15) for NO; and 1.07 (95% CI, 1.00-1.13) for NO2. For female children, they were for 1.03 (95% CI, 0.90-1.18) for PM2.5; 0.98 (95% CI, 0.83-1.13) for NO; and 1.00 (95% CI, 0.86-1.16) for NO2. Conclusions and Relevance: In a population-based birth cohort, we detected an association between exposure to NO and ASD but no significant association with PM2.5 and NO2.

Prenatal antidepressant exposure associated with CYP2E1 DNA methylation change in neonates.

Some but not all neonates are affected by prenatal exposure to serotonin reuptake inhibitor antidepressants (SRI) and maternal mood disturbances. Distinguishing the impact of these 2 exposures is challenging and raises critical questions about whether pharmacological, genetic, or epigenetic factors can explain the spectrum of reported outcomes. Using unbiased DNA methylation array measurements followed by a detailed candidate gene approach, we examined whether prenatal SRI exposure was associated with neonatal DNA methylation changes and whether such changes were associated with differences in birth outcomes. Prenatal SRI exposure was first associated with increased DNA methylation status primarily at CYP2E1(ß(Non-exposed) = 0.06, ß(SRI-exposed) = 0.30, FDR = 0); however, this finding could not be distinguished from the potential impact of prenatal maternal depressed mood. Then, using pyrosequencing of CYP2E1 regulatory regions in an expanded cohort, higher DNA methylation status--both the mean across 16 CpG sites (P < 0.01) and at each specific CpG site (P < 0.05)--was associated with exposure to lower 3rd trimester maternal depressed mood symptoms only in the SRI-exposed neonates, indicating a maternal mood x SRI exposure interaction. In addition, higher DNA methylation levels at CpG2 (P = 0.04), CpG9 (P = 0.04) and CpG10 (P = 0.02), in the interrogated CYP2E1 region, were associated with increased birth weight independently of prenatal maternal mood, SRI drug exposure, or gestational age at birth. Prenatal SRI antidepressant exposure and maternal depressed mood were associated with altered neonatal CYP2E1 DNA methylation status, which, in turn, appeared to be associated with birth weight.

Age-related sensitive periods influence visual language discrimination in adults.

Adults as well as infants have the capacity to discriminate languages based on visual speech alone. Here, we investigated whether adults' ability to discriminate languages based on visual speech cues is influenced by the age of language acquisition. Adult participants who had all learned English (as a first or second language) but did not speak French were shown faces of bilingual (French/English) speakers silently reciting sentences in either language. Using only visual speech information, adults who had learned English from birth or as a second language before the age of 6 could discriminate between French and English significantly better than chance. However, adults who had learned English as a second language after age 6 failed to discriminate these two languages, suggesting that early childhood exposure is crucial for using relevant visual speech information to separate languages visually. These findings raise the possibility that lowered sensitivity to non-native visual speech cues may contribute to the difficulties encountered when learning a new language in adulthood.

Prenatal serotonin reuptake inhibitor (SRI) antidepressant exposure and serotonin transporter promoter genotype (SLC6A4) influence executive functions at 6 years of age.

Prenatal exposure to serotonin reuptake inhibitor (SRI) antidepressants and maternal depression may affect prefrontal cognitive skills (executive functions; EFs) including self-control, working memory and cognitive flexibility. We examined long-term effects of prenatal SRI exposure on EFs to determine whether effects are moderated by maternal mood and/or genetic variations in SLC6A4 (a gene that codes for the serotonin transporter [5-HTT] central to the regulation of synaptic serotonin levels and behavior). Children who were exposed to SRIs prenatally (SRI-exposed N = 26) and non-exposed (N = 38) were studied at age 6 years (M = 6.3; SD = 0.5) using the Hearts & Flowers task (H&F) to assess EFs. Maternal mood was measured during pregnancy (3rd trimester) and when the child was age 6 years (Hamilton Depression Scale). Parent reports of child behavior were also obtained (MacArthur Health & Behavior Questionnaire). Parents of prenatally SRI-exposed children reported fewer child externalizing and inattentive (ADHD) behaviors. Generalized estimate equation modeling showed a significant 3-way interaction between prenatal SRI exposure, SLC6A4 variant, and maternal mood at the 6-year time-point on H&F accuracy. For prenatally SRI-exposed children, regardless of maternal mood, the H&F accuracy of children with reduced 5HTT expression (a short [S] allele) remained stable. Even with increasing maternal depressive symptoms (though all below clinical threshold), EFs of children with at least one short allele were comparable to children with the same genotype whose mothers reported few if any depressive symptoms-in this sense they showed resilience. Children with two long (L) alleles were more sensitive to context. When their mothers had few depressive symptoms, LL children showed extremely good EF performance-better than any other group. When their mothers reported more depressive symptoms, LL children's EF performance was worse than that of any other group. In the face of a mother with a more depressed mood, EFs were best preserved in children prenatally exposed to SRIs and with at least one short SLC6A4 allele. Yet, prenatally-exposed LL children hold out promise of possibly superior EF if their mother's mood remains euthymic or improves.

The impact of prenatal serotonin reuptake inhibitor (SRI) antidepressant exposure and maternal mood on mother-infant interactions at 3 months of age.

Exposure to maternal depression increases risks for altered mother-infant interactions. Serotonin reuptake inhibitor (SRI) antidepressants are increasingly prescribed to manage antenatal maternal illness. The impact of SRIs on early mother-infant interactions was unknown. Three-month-old infants of 32 depressed mothers treated with SRI medications during pregnancy and 43 non-medicated mothers were studied. Using an established face-to-face mother-infant interaction paradigm, dyad interactions were studied with and without a toy. Videotaped sessions yielded 4 measures: maternal sensitivity, dyadic organization, infant readiness to interact, and maternal interruptive behaviors. Even with prenatal SRI treatment, depressed mothers interrupted their infants more during toy play. In the absence of prenatal SRI treatment, maternal postnatal depression adversely influenced infant behavior. Higher levels of maternal depression symptoms at 3 months predicted poorer infant readiness to interact during the toy session. Conversely, in the SRI-exposed group, higher prenatal depression scores predicted greater infant readiness to interact at 3 months. Increased infant readiness with SRI exposure suggests a "fetal programming effect" whereby prenatal maternal mood disturbances shaped a future response to a postnatal depressed maternal environment.

Prenatal exposure to antidepressants and depressed maternal mood alter trajectory of infant speech perception.

Language acquisition reflects a complex interplay between biology and early experience. Psychotropic medication exposure has been shown to alter neural plasticity and shift sensitive periods in perceptual development. Notably, serotonin reuptake inhibitors (SRIs) are antidepressant agents increasingly prescribed to manage antenatal mood disorders, and depressed maternal mood per se during pregnancy impacts infant behavior, also raising concerns about long-term consequences following such developmental exposure. We studied whether infants' language development is altered by prenatal exposure to SRIs and whether such effects differ from exposure to maternal mood disturbances. Infants from non-SRI-treated mothers with little or no depression (control), depressed but non-SRI-treated (depressed-only), and depressed and treated with an SRI (SRI-exposed) were studied at 36 wk gestation (while still in utero) on a consonant and vowel discrimination task and at 6 and 10 mo of age on a nonnative speech and visual language discrimination task. Whereas the control infants responded as expected (success at 6 mo and failure at 10 mo) the SRI-exposed infants failed to discriminate the language differences at either age and the depressed-only infants succeeded at 10 mo instead of 6 mo. Fetuses at 36 wk gestation in the control condition performed as expected, with a response on vowel but not consonant discrimination, whereas the SRI-exposed fetuses showed accelerated perceptual development by discriminating both vowels and consonants. Thus, prenatal depressed maternal mood and SRI exposure were found to shift developmental milestones bidirectionally on infant speech perception tasks.

A bilingual advantage in visual language discrimination in infancy.

The origins of the bilingual advantage in various cognitive tasks are largely unknown. We tested the hypothesis that bilinguals' early capacities to track their native languages separately and learn about the properties of each may be at the origin of such differences. Spanish-Catalan bilingual and Spanish or Catalan monolingual infants watched silent video recordings of French-English bilingual speakers and were tested on their ability to discern when the language changed from French to English or vice versa. The infants' performance was compared with that of previously tested French-English bilingual and English monolingual infants. Although all groups of monolingual infants failed to detect the change between English and French, both groups of bilingual infants succeeded. These findings reveal that bilingual experience can modulate the attentional system even without explicit training or feedback. They provide a basis for explaining the ontogeny of the general cognitive advantages of bilinguals.

Discriminating languages by speech-reading.

The goal of this study was to explore the ability to discriminate languages using the visual correlates of speech (i.e., speech-reading). Participants were presented with silent video clips of an actor pronouncing two sentences (in Catalan and/or Spanish) and were asked to judge whether the sentences were in the same language or in different languages. Our results established that Spanish-Catalan bilingual speakers could discriminate running speech from their two languages on the basis of visual cues alone (Experiment 1). However, we found that this ability was critically restricted by linguistic experience, since Italian and English speakers who were unfamiliar with the test languages could not successfully discriminate the stimuli (Experiment 2). A test of Spanish monolingual speakers revealed that knowledge of only one of the two test languages was sufficient to achieve the discrimination, although at a lower level of accuracy than that seen in bilingual speakers (Experiment 3). Finally, we evaluated the ability to identify the language by speech-reading particularly distinctive words (Experiment 4). The results obtained are in accord with recent proposals arguing that the visual speech signal is rich in informational content, above and beyond what traditional accounts based solely on visemic confusion matrices would predict.

Visual language discrimination in infancy.

This study shows that 4- and 6-month-old infants can discriminate languages (English from French) just from viewing silently presented articulations. By the age of 8 months, only bilingual (French-English) infants succeed at this task. These findings reveal a surprisingly early preparedness for visual language discrimination and highlight infants' selectivity for retaining only necessary perceptual sensitivities.