Visual Habituation Procedure Research Articles

Space modulates cross-domain transfer of abstract rules in infants

Developmental studies have shown that infants exploit ordinal information to extract and generalize repetition-based rules from a sequence of items. Within the visual modality, this ability is constrained by the spatial layout within which items are delivered given that a left-to-right orientation boosts infants’ rule learning, whereas a right-to-left orientation hinders this ability. Infants’ rule learning operates across different domains and can also be transferred across modalities when learning is triggered by speech. However, no studies have investigated whether the transfer of rule learning occurs across different domains when language is not involved. Using a visual habituation procedure, we tested 7-month-old infants’ ability to extract rule-like patterns from numerical sequences and generalize them to non-numerical sequences of visual shapes and whether this ability is affected by the spatial orientation. Infants were first habituated to left-to-right or right-to-left oriented numerical sequences instantiating an ABB rule and were then tested with the familiar rule instantiated across sequences of single geometrical shapes and a novel (ABA) rule. Results showed a transfer of learning from number to visual shapes for left-to-right oriented sequences but not for right-to-left oriented ones (Experiment 1) even when the direction of the numerical change (increasing vs. decreasing) within the habituation sequences violated a small–left/large–right number–space association (Experiment 2). These results provide the first demonstration that visual rule learning mechanisms in infancy operate at a high level of abstraction and confirm earlier findings that left-to-right oriented directional cues facilitate infants’ representation of order.

Rule learning transfer across linguistic and visual modalities in 7-month-old infants.

Rule learning (RL) refers to infants' ability to extract high-order, repetition-based rules from a sequence of elements and to generalize them to new items. RL has been demonstrated in both the auditory and the visual modality, but no studies have investigated infants' transfer of learning across these two modalities, a process that is fundamental for the development of many complex cognitive skills. Using a visual habituation procedure within a cross-modal RL task, we tested 7-month-old infants' transfer of learning both from speech to vision (auditory-visual-AV-condition) and from vision to speech (visual-auditory-VA-condition). Results showed a transfer of learning in the AV condition, but only for those infants who were able to efficiently extract the rule during the learning (habituation) phase. In contrast, in the VA condition infants provided no evidence of RL. Overall, this study indicates that 7-month-old infants can transfers high-order rules across modalities with an advantage for transferring from speech to vision, and that this ability is constrained by infants' individual differences in the way they process the to-be-learned rules.

Factors Affecting Speech Discrimination in Children with Cochlear Implants: Evidence from Early-Implanted Infants.

To learn words and acquire language, children must be able to discriminate and correctly perceive phonemes. Although there has been much research on the general language outcomes of children with cochlear implants (CIs), little is known about the development of speech perception with regard to specific speech processes, such as speech discrimination. The purpose of this study was to investigate the development of speech discrimination in infants with CIs and identify factors that might correlate with speech discrimination skills. Using a Hybrid Visual Habituation procedure, we tested infants with CIs on their ability to discriminate the vowel contrast /i/-/u/. We also gathered demographic and audiological information about each infant. Children who had received CIs before 2 yr of age served as participants. We tested the children at two post cochlear implantation intervals: 2-4 weeks post CI stimulation (N = 17) and 6-9 mo post CI stimulation (N = 10). The infants' mean looking times during the novel versus old trials of the experiment were measured. A linear regression model was used to evaluate the relationship between the normalized looking time difference and the following variables: chronological age, age at CI stimulation, gender, communication mode, and best unaided pure-tone average. We found that the best unaided pure-tone average predicted speech discrimination at the early interval. In contrast to some previous speech perception studies that included children implanted before 3 yr of age, age at CI stimulation did not predict speech discrimination performance. The results suggest that residual acoustic hearing before implantation might facilitate speech discrimination during the early period post cochlear implantation; with more hearing experience, communication mode might have a greater influence on the ability to discriminate speech. This and other studies on age at cochlear implantation suggest that earlier implantation might not have as large an effect on speech perception as it does on other language skills.

Auditory Discrimination of Lexical Stress Patterns in Hearing-Impaired Infants with Cochlear Implants Compared with Normal Hearing: Influence of Acoustic Cues and Listening Experience to the Ambient Language.

To assess discrimination of lexical stress pattern in infants with cochlear implant (CI) compared with infants with normal hearing (NH). While criteria for cochlear implantation have expanded to infants as young as 6 months, little is known regarding infants' processing of suprasegmental-prosodic cues which are known to be important for the first stages of language acquisition. Lexical stress is an example of such a cue, which, in hearing infants, has been shown to assist in segmenting words from fluent speech and in distinguishing between words that differ only the stress pattern. To date, however, there are no data on the ability of infants with CIs to perceive lexical stress. Such information will provide insight to the speech characteristics that are available to these infants in their first steps of language acquisition. This is of particular interest given the known limitations that the CI device has in transmitting speech information that is mediated by changes in fundamental frequency. Two groups of infants participated in this study. The first group included 20 profoundly hearing-impaired infants with CI, 12 to 33 months old, implanted under the age of 2.5 years (median age of implantation = 14.5 months), with 1 to 6 months of CI use (mean = 2.7 months) and no known additional problems. The second group of infants included 48 NH infants, 11 to 14 months old with normal development and no known risk factors for developmental delays. Infants were tested on their ability to discriminate between nonsense words that differed on their stress pattern only (/dóti/ versus /dotí/ and /dotí/ versus /dóti/) using the visual habituation procedure. The measure for discrimination was the change in looking time between the last habituation trial (e.g., /dóti/) and the novel trial (e.g., /dotí/). (1) Infants with CI showed discrimination between lexical stress pattern with only limited auditory experience with their implant device, (2) discrimination of stress patterns in infants with CI was reduced compared with that of infants with NH, (3) both groups showed directional asymmetry in discrimination, that is, increased discrimination from the uncommon to the common stress pattern in Hebrew (/dóti/ versus /dotí/) compared with the reversed condition. The CI device transmitted sufficient acoustic information (amplitude, duration, and fundamental frequency) to allow discrimination between stress patterns in young hearing-impaired infants with CI. The present pattern of results is in support of a discrimination model in which both auditory capabilities and "top-down" interactions are involved. That is, the CI infants detected changes between stressed and unstressed syllables after which they developed a bias for the more common weak-strong stress pattern in Hebrew. The latter suggests that infants with CI were able to extract the statistical distribution of stress patterns by listening to the ambient language even after limited auditory experience with the CI device. To conclude, in relation to processing of lexical stress patterns, infants with CI followed similar developmental milestones as hearing infants thus establishing important prerequisites for early language acquisition.

Who is the dynamic duo? How infants learn about the identity of objects in a causal chain.

Four experiments investigated infants' and adults' knowledge of the identity of objects in a causal sequence of events. In Experiments 1 and 2, 18- and 22-month-olds in the visual habituation procedure were shown a 3-step causal chain event in which the relation between an object's part (dynamic or static) and its causal role was either consistent or inconsistent with the real-world. In Experiment 3, 22-month-olds were tested with a delayed launching causal chain in which the second object, rather than the first, was the agent of the outcome. In Experiment 4, adults were shown the same events and were asked to judge whether the first or second object in the causal chain was animate or inanimate. Experiments 1 and 2 revealed that 18-month-olds were unconstrained in the part-causal role relations they would encode, but 22-month-olds learned only those relations that were consistent with the real-world. Experiment 3 showed that 22-month-olds expect the second object in a delayed launching sequence to possess a dynamic, moving part. Experiment 4 showed that adults expect the first object of a causal chain to be animate and the second object to be inanimate. The results are discussed with regard to the developmental timetable for causal learning and the mechanisms for early concept acquisition.

The effect of listening experience on the discrimination of /ba/ and /pa/ in Hebrew-learning and Arabic-learning infants

Infant speech discrimination can follow multiple trajectories depending on the language and the specific phonemes involved. Two understudied languages in terms of the development of infants’ speech discrimination are Arabic and Hebrew. PurposeThe purpose of the present study was to examine the influence of listening experience with the native language on the discrimination of the voicing contrast /ba-pa/ in Arabic-learning infants whose native language includes only the phoneme /b/ and in Hebrew-learning infants whose native language includes both phonemes. Method128 Arabic-learning infants and Hebrew-learning infants, 4-to-6 and 10-to-12-month-old infants, were tested with the Visual Habituation Procedure. ResultsThe results showed that 4-to-6-month-old infants discriminated between /ba-pa/ regardless of their native language and order of presentation. However, only 10-to-12-month-old infants learning Hebrew retained this ability. 10-to-12-month-old infants learning Arabic did not discriminate the change from /ba/ to /pa/ but showed a tendency for discriminating the change from /pa/ to /ba/. ConclusionsThis is the first study to report on the reduced discrimination of /ba-pa/ in older infants learning Arabic. Our findings are consistent with the notion that experience with the native language changes discrimination abilities and alters sensitivity to non-native contrasts, thus providing evidence for ‘top-down’ processing in young infants. The directional asymmetry in older infants learning Arabic can be explained by assimilation of the non-native consonant /p/ to the native Arabic category /b/ as predicted by current speech perception models.

Infants Discriminate Voicing and Place of Articulation With Reduced Spectral and Temporal Modulation Cues.

This study assessed the role of spectro-temporal modulation cues in the discrimination of 2 phonetic contrasts (voicing and place) for young infants. A visual-habituation procedure was used to assess the ability of French-learning 6-month-old infants with normal hearing to discriminate voiced versus unvoiced (/aba/-/apa/) and labial versus dental (/aba/-/ada/) stop consonants. The stimuli were processed by tone-excited vocoders to degrade frequency-modulation cues while preserving: (a) amplitude-modulation (AM) cues within 32 analysis frequency bands, (b) slow AM cues only (<16 Hz) within 32 bands, and (c) AM cues within 8 bands. Infants exhibited discrimination responses for both phonetic contrasts in each processing condition. However, when fast AM cues were degraded, infants required a longer exposure to vocoded stimuli to reach the habituation criterion. Altogether, these results indicate that the processing of modulation cues conveying phonetic information on voicing and place is "functional" at 6 months. The data also suggest that the perceptual weight of fast AM speech cues may change during development.

Assessing speech perception in children with cochlear implants using a modified hybrid visual habituation procedure.

The objectives of this research were to determine whether an adapted version of a Hybrid Visual Habituation procedure could be used to assess speech perception of phonetic and prosodic features of speech (vowel height, lexical stress, and intonation) in individual pre-school-age children who use cochlear implants. Nine children ranging in age from 3;4 to 5;5 participated in this study. Children were prelingually deaf and used cochlear implants and had no other known disabilities. Children received two speech feature tests using an adaptation of a Hybrid Visual Habituation procedure. Seven of the nine children demonstrated perception of at least one speech feature using this procedure using results from a Bayesian linear regression analysis. At least one child demonstrated perception of each speech feature using this assessment procedure. An adapted version of the Hybrid Visual Habituation Procedure with an appropriate statistical analysis provides a way to assess phonetic and prosodicaspects of speech in pre-school-age children who use cochlear implants.

Internal Working Models of Toddlers: A Bridge from Maternal Sensitivity to Toddlers' Attachment Behaviors

Internal working models are based on young children's expectations for the behavior of their attachment figures that develop into broader representations of their relational experiences, and decision rules about how to interact with others. These internal working models are thought to influence the child's subsequent processing of social experiences and allow the child to anticipate, plan for, and adapt to his or her social world. Current research studies largely concentrated on the internal working models of attachment in childhood and adulthood; very little inquiry has been conducted on internal working models of preverbal infants and toddlers. It was not until 2007 that a study by Johnson, Dweck and Chen had found evidence for infants' internal working models of attachment using a habituation paradigm. In addition, some theorists and researchers have indicated that maternal sensitivity is associated with internal working models in childhood; and also it has been suggested that maternal sensitivity may affect toddler's attachment status. Therefore, internal working models may play an important role in relationship between maternal sensitivity and toddler's attachment status. However, there is inadequate research on maternal sensitivity and internal working models in infancy. The present study explored the relationship between toddlers' attachment status, maternal sensitivity and internal working models of toddlers. We hypothesized that toddlers of different attachment status might have unique patterns of expectations about their mother's responsive behavior, and the expectations might correspond to maternal sensitivity in caregiver-infant interactions. Forty-one toddlers(M = 14.01 months, SD = 0.81) and their mothers from middle class backgrounds participated in the study. A visual habituation study using abstract animations with separation and reunion events was conducted to test a part of the toddlers' internal working models—their expectations of a caregiver's responsiveness. Toddlers' attachment status was assessed by the Strange Situation procedure. Maternal sensitivity in caregiver–toddler interactions was measured by Maternal Behavior Q-Sort. The data was analyzed using repeated-measure analysis of variance, chi-square analyses, paired t tests, q-factor analysis and LCA. Results were as follows:(1) Toddlers' expectations of a caregiver's responsiveness depended on their own attachment status: insecure toddlers expected their caregivers to withhold comfort;(2) Toddlers' expectations of a caregiver's responsiveness depended on their mother's behavior: the toddlers of Self-centered mothers expected caregivers to be unresponsive;(3) The results found by LCA indicated that there were two types of attachment system: Category 1, the toddlers of Child-centered mothers tended to expect their caregivers to be responsive, and showed secure attachment behaviors. Category 2, the toddlers of Self-centered mothers tended to expect their caregivers to be unresponsive, and showed insecure attachment behaviors in Strange Situation procedure. These results indicated that it was effective to using a visual habituation procedure to measure internal working models of preverbal toddlers. The claims that toddlers' internal working models play an important role in the relationship between maternal sensitivity and toddler's attachment status can be supported. If we want to change the attachment status of toddlers through their internal working models, we should pay attention to the behavior of their mothers.

Visual habituation paradigm with adults with profound intellectual and multiple disabilities: a new way for cognitive assessment?

The use of common psychological assessment tools is invalidated with persons with PIMD. The aim of this study was to test the feasibility of using a visual habituation procedure with a group of adults with PIMD, to develop a new theoretical and practical framework for the assessment of cognitive abilities. To test the existence of the habituation/novelty reaction phenomenon with adults with PIMD, fifteen participants were exposed repeatedly to two different objects, following the principles of a participant-controlled procedure. Both qualitative and quantitative analyses were carried out. Participants presented the same habituation profiles generally obtained in infancy research. Stimulus presentation has a significant impact on the participants' visual behaviour and fixation measurement appears to be an interesting indicator as to how an individual with PIMD is able to process external information. The elaboration of perceptual tasks based on a visual habituation method is one of the major implications of these results.

Within‐rhythm Class Native Language Discrimination Abilities of Basque‐Spanish Monolingual and Bilingual Infants at 3.5 Months of Age

Language rhythm determines young infants' language discrimination abilities. However, it is unclear whether young bilingual infants exposed to rhythmically similar languages develop sensitivities to cross‐linguistic rhythm cues to discriminate their dual language input. To address this question, 3.5‐month‐old monolingual Basque, monolingual Spanish and bilingual Basque‐Spanish infants' language discrimination abilities (across low‐pass filtered speech samples of Basque and Spanish) have been tested using the visual habituation procedure. Although falling within the same rhythmic class, Basque and Spanish exhibit significant differences in their distributions of vocalic intervals (within‐rhythmic class variation). All infant groups in our study successfully discriminated between the languages, although each group exhibited a different pattern. Monolingual Spanish infants succeeded only when they heard Basque during habituation, suggesting that they were influenced by native language recognition. The bilingual and the Basque monolingual infants showed no such asymmetries and succeeded irrespective of the language of habituation. Additionally, bilingual infants exhibited longer looking times in the test phase as compared with monolinguals, reflecting that bilingual infants attend to their native languages differently than monolinguals. Overall, results suggest that bilingual infants are sensitive to within‐rhythm acoustic regularities of their native language(s) facilitating language discrimination and hence supporting early bilingual acquisition.

Rational action selection in 1½- to 3-year-olds following an extended training experience

Previous studies failed to find evidence for rational action selection in children under 2 years of age. The current study investigated whether younger children required more training to encode the relevant causal relationships. Children between 1½ and 3 years of age were trained over two sessions to perform actions on a touch-sensitive screen to obtain video clips as outcomes. Subsequently, a visual habituation procedure was employed to devalue one of the training outcomes. As in previous studies, 2- and 3-year-olds chose actions associated with an expected valued outcome significantly more often during a subsequent choice test. Moreover, analysis of children’s first responses in the post-devaluation test revealed evidence of rational action selection even in the youngest age group (18–23 months). Consistent with dual-process accounts of action control, the findings support the view that the ability to make rational action choices develops gradually.

Modified Spectral Tilt Affects Older, but Not Younger, Infants' Native-Language Fricative Discrimination

It is important to ensure that hearing aid fitting strategies for infants take into account the infant's developing speech perception system. As a way of exploring this issue, this study examined how 6- and 9-month-olds with normal hearing perceive native-language speech in which the natural spectral shape was altered to emphasize either high-frequency (positive spectral tilt) or low-frequency (negative spectral tilt) information. Discrimination was tested using a visual habituation procedure. Forty-eight 6-month-olds and forty-eight 9-month-olds were presented with a fricative contrast, /f/-/s/, in 1 of 3 conditions: (a) as unmodified speech; (b) with a -6 dB/octave tilt; or (c) with a +6 dB/octave tilt. Six-month-olds showed evidence of discriminating /f/-/s/ in all 3 conditions, but 9-month-olds showed such evidence only in the unmodified condition. The findings suggest that the perceptual reorganization that emerges for consonants at the end of the first year affects 9-month-olds' discrimination of native speech sounds. Perceptual reorganization is usually indexed by a decline in the ability to discriminate nonnative speech sounds. In this study, 6-month-olds demonstrated an acoustic-based sensitivity to both modified and unmodified native speech sounds, but 9-month-olds were most sensitive to the unmodified speech sounds that adhered to the native spectral profile.

Infant dialect discrimination.

To understand speech, infants must differentiate between phonetic changes that are linguistically contrastive and those that are not. Research has shown that infants are very sensitive to fine-grained differences in speech sounds that differentiate words in their own or another language. However, little is known about infants' ability to discriminate phonetic differences associated with different dialects of their native language. Using a visual habituation procedure, 7-, 11-, 18-, 24-, and 30-month olds were tested on their ability to discriminate two linguistically equivalent variants of the diphthong (/aI/)—one produced in their native dialect (North Midland American English) versus one produced in a non-native dialect (Southern American English). Seven-month olds discriminated the variants but 11-month olds did not. Infants from 18–30 months of age did not demonstrate statistically significant discrimination, but they did show a trend toward discrimination with increasing age. The findings suggest that dialect discrimination follows a U-shaped course of development. Because 11-month olds demonstrated the poorest dialect discrimination performance, we are currently assessing their ability to discriminate linguistically different speech sounds varying in degree of acoustic similarity. Preliminary findings suggest that both language experience and acoustic differences may influence infants' discrimination of phonetic contrasts in the native language. [Work supported by NIH-NIDCD Grant (R01DC006235), an IUPUI Educational Enhancement Grant, and grants from the IUPUI UROP and SROP Programs.]

Language background influences the emergence of voice onset time production and perception.

This study investigates the production and perception of voice onset time (VOT) among preschool children who acquired English and French simultaneously compared to monolingual peers of these two languages. Children participated in this study at the age of 18 months and returned at 24 months for a second session. During each session the children took part in a visual habituation procedure to evaluate discrimination of VOT using edited natural /b/+ vowel and /p/ + vowel syllables in a task format developed by Houston et al. (2007) to assess individual performance. In this task, three VOT values (produced by several talkers) were presented to the children: one within adult norms of the language for voiced bilabial consonants; one within the adult norms of the language for voiceless bilabial consonants; and one between the means for the voiced and voiceless consonants. The children also participated in a structured play session, and their spontaneous productions of word initial stops were acoustically analyzed to measure VOT. Preliminary analysis indicates that accuracy in discriminating VOT precedes production of voicing contrasts for all groups, and monolinguals appear to have developed adultlike perception and production of voicing at a younger age than their bilingual peers.

Do as I do: 7‐month‐old infants selectively reproduce others’ goals

In the current study, we tested whether 7-month-old infants would selectively imitate the goal-relevant aspects of an observed action. Infants saw an experimenter perform an action on one of two small toys and then were given the opportunity to act on the toys. Infants viewed actions that were either goal-directed or goal-ambiguous, and that represented either completed or uncompleted goals. Infants reproduced the goal of the experimenter only in those cases where the action was goal-directed, in both the complete and incomplete goal conditions. These results provide the first evidence that infants as young as 7 months of age selectively imitate actions based on their goal-directedness, and that they are able to analyze the goals of even uncompleted actions. Even during the first year of life, infants' sensitivity to goal-directed action is expressed not only in their responses in visual habituation procedures, but also in their overt actions.

Les effets de la contingence lors d'une tâche d'habituation visuelle chez les nourrissons de 3 et 6 mois.

Thirty-six 3-month old infants and the same number of 6-month old infants underwent three visual habituation procedures differentiated by degree of behavioural contingency. Results showed significant differences between conditions only for the six-month olds: the lower the contingency, the higher the visual fixation scores. Results support some of the propositions that Gergely and Watson (1996, 1999) have put forth regarding the developmental model for detecting contingencies. The results also challenge the traditional model for visual habituation which suggests that varied durations of visual fixation should basically be determined by the visual characteristics of the stimulus.

Assessing Speech Discrimination in Individual Infants.

Assessing speech discrimination skills in individual infants from clinical populations (e.g., infants with hearing impairment) has important diagnostic value. However, most infant speech discrimination paradigms have been designed to test group effects rather than individual differences. Other procedures suffer from high attrition rates. In this study, we developed 4 variants of the Visual Habituation Procedure (VHP) and assessed their robustness in detecting individual 9-month-old infants' ability to discriminate highly contrastive nonwords. In each variant, infants were first habituated to audiovisual repetitions of a nonword (seepug) before entering the test phase. The test phase in Experiment 1 (extended variant) consisted of 7 old trials (seepug) and 7 novel trials (boodup) in alternating order. In Experiment 2, we tested 3 novel variants that incorporated methodological features of other behavioral paradigms. For the oddity variant, only 4 novel trials and 10 old trials were used. The stimulus alternation variant was identical to the extended variant except that novel trials were replaced with "alternating" trials-trials that contained repetitions of both the old and novel nonwords. The hybrid variant incorporated elements from both the oddity and the stimulus alternation variants. The hybrid variant proved to be the most successful in detecting statistically significant discrimination in individual infants (8 out of 10), suggesting that both the oddity and the stimulus alternation features contribute to providing a robust methodology for assessing discrimination in individual infants. In Experiment 3, we found that the hybrid variant had good test-retest reliability. Implications of these results for future infant speech perception work with clinical populations are discussed.

Speech discrimination skills in deaf infants before and after cochlear implantation

The benefit of early cochlear implantation (CI) to later speech perception outcomes in prelingually deaf (PLD) children is well established and implantation of infants has become more prevalent. The aim of this study was to determine whether or not deaf infants could discriminate audiovisual non-words shortly after CI and whether their attention to speech and non-speech audiovisual stimuli was similar to infants with normal hearing (NH). Three groups of participants were tested: PLD infants tested prior to CI (pre-CI), PLD infants tested post-implantation (post-CI), and a group of age-matched NH infants. A novel version of the visual habituation (VH) procedure was used. Infants were presented repetitions of an audiovisual non-word until their looking-time decreased to a predetermined criterion. They were then presented two types of test trials: repetitions of the old word (non-alternating (NA) trials) and repetitions of a novel non-word alternating with the old word (alternating (A) trials). Longer lookin...

Cochlear Implantation in Deaf Infants

With the application of universal newborn hearing screening programs, a large pool of newly identified deaf infants has been identified. The benefits of early intervention with cochlear implants (CI) is being explored. Mounting evidence suggests that age at implantation is a strong predictor of language outcomes. However, new behavioral procedures are needed to measure speech and language skills during infancy. Also, procedures are needed to analyze the speech input to young CI recipients. Cohort-sequential. Thirteen infants with profound hearing loss who were implanted between the ages of 6 to 12 months of age participated in this study. Eight participated in two new behavioral methodologies: 1) the visual habituation procedure to assess their discrimination of speech sounds; 2) the preferential looking paradigm to assess their ability to learn associations between speech sounds and objects. Older implanted infants and normal-hearing infants were also tested for comparison. The pitch of mothers' speech to infants was analyzed. Patterns of looking times for the very early implanted infants were similar to those of normal hearing infants. Mothers' speech to infants with CIs was similar in pitch to normal-hearing infants who had the same duration of experience with sounds. No surgical or anesthetic complications occurred in this group of infants, and the pattern of listening skill development mirrors that seen in normal-hearing infants. Mothers adjust their speech to suit the listening experience of their infants.