Phonotactic regularities in the segmentation of spoken Italian

Five word-spotting experiments explored the role of consonantal and vocalic phonotactic cues in the segmentation of spoken Italian. The first set of experiments tested listeners' sensitivity to phonotactic constraints cueing syllable boundaries. Participants were slower in spotting words in nonsense strings when target onsets were misaligned (e.g., lago in ri.blago) than when they were aligned (e.g., lago in rin.lago) with phonotactically determined syllabic boundaries. This effect held also for sequences that occur only word-medially (e.g., /tl/ in ri.tlago), and competition effects could not account for the disadvantage in the misaligned condition. Similarly, target detections were slower when their offsets were misaligned (e.g., cittá in cittáu.ba) than when they were aligned (e.g., cittá in cittá.oba) with a phonotactic syllabic boundary. The second set of experiments tested listeners' sensitivity to phonotactic cues, which specifically signal lexical (and not just syllable) boundaries. Results corroborate the role of syllabic information in speech segmentation and suggest that Italian listeners make little use of additional phonotactic information that specifically cues word boundaries.     

Use of phonetic specificity during the acquisition of new words: differences between consonants and vowels

The present study explores the issue of the use of phonetic specificity in the process of learning new words at 20 months of age. The procedure used follows Nazzi and Gopnik [Nazzi, T., & Gopnik, A. (2001). Linguistic and cognitive abilities in infancy: When does language become a tool for categorization? Cognition, 80, B11-B20]. Infants were first presented with triads of perceptually dissimilar objects, which were given made-up names, two of the objects receiving the same name. Then, word learning was evaluated through object selection/categorization. Tests involved phonetically different words (e.g. [pize] vs. [mora], Experiment 1), words differing minimally on their onset consonant (e.g. [pize] vs. [tize], Experiment 2a), and conditions which had never been tested before: non-initial consonantal contrasts (e.g. [pide] vs. [pige], Experiment 2b), and vocalic contrasts (e.g. [pize] vs. [pyze]; [pize] vs. [paze]; [pize] vs. [pizu], Experiments 3a-c). Results differed across conditions: words could be easily learnt in the phonetically different condition, and were learnt, though to a lesser degree, in both the initial and non-initial minimal consonant contrast; however, infants' global performance on all three vocalic contrasts was at chance level. The present results shed new light regarding the specificity of early words, and raise the possibility of different contributions for vowels and consonants in early word learning.     

Priming infants to attend to color and pattern information in an individuation task

Wilcox (Cognition 72 (1999) 125) reported that infants are more sensitive to form than surface features when individuating objects in occlusion events: it is not until 7.5 months that infants spontaneously use pattern information, and 11.5 months that they spontaneously use color information, as the basis for object individuation. The present research assessed the extent to which infants' sensitivity to surface features could be increased under more supportive conditions. More specifically, we examined whether younger infants could be primed to draw on color and pattern features in an individuation task if they were first shown the functional value of attending to color and pattern information (i.e. the color or the pattern of an object predicted the function it would engage in). Five experiments were conducted with infants 4.5 to 9.5 months of age. The main findings were that 9.5- and 7.5-month-olds could be primed to use color information, and 5.5- and 4.5-month-olds could be primed to attend to pattern information, after viewing the function events. The results are discussed in terms of the kinds of experiences that can lead to increased sensitivity to surface features and the mechanisms that support feature priming in young infants.     

Event-mapping tasks: investigating the effects of prior information and event complexity on performance

Infants younger than 11.5 months typically fail in event-mapping tasks with complex event sequences, yet succeed when the event sequences are made very simple and brief. The present research explored whether younger infants might succeed at mapping complex event sequences if infants were given information to help them organize and structure the event. Three experiments were conducted with 7.5-month-olds. In all of the experiments, the infants were shown a two-phase test event. In the first phase, infants saw a box–ball occlusion sequence in which the objects emerged at least once to each side of the screen, reversing direction each time to return behind the screen. In the second phase, infants saw a one-ball display. Prior to the test trials, infants were shown an “outline” of the test event that contained the basic components of the event. The experiments varied in (a) the kind of information included in the event outline and (b) the complexity of the box–ball test sequence (i.e., the number of object reversals). The results revealed that the 7.5-month-olds benefitted from viewing an event outline, although the performance of the males was more robust than the females. These results add to a growing body of research indicating that young infants can succeed on event-mapping tasks under more supportive conditions and provide insight into why event mapping is such a difficult task for young infants.     

Phonotactic regularities in the segmentation of spoken Italian

Five word-spotting experiments explored the role of consonantal and vocalic phonotactic cues in the segmentation of spoken Italian. The first set of experiments tested listeners’ sensitivity to phonotactic constraints cueing syllable boundaries. Participants were slower in spotting words in nonsense strings when target onsets were misaligned (e.g., lago in ri.blago) than when they were aligned (e.g., lago in rin.lago) with phonotactically determined syllabic boundaries. This effect held also for sequences that occur only word-medially (e.g., /tl/ in ri.tlago), and competition effects could not account for the disadvantage in the misaligned condition. Similarly, target detections were slower when their offsets were misaligned (e.g., cittá in cittáu.ba) than when they were aligned (e.g., cittá in cittá.oba) with a phonotactic syllabic boundary. The second set of experiments tested listeners’ sensitivity to phonotactic cues, which specifically signal lexical (and not just syllable) boundaries. Results corroborate the role of syllabic information in speech segmentation and suggest that Italian listeners make little use of additional phonotactic information that specifically cues word boundaries.     

Young children's ability to solve spatial problems involving a choice

When do young children become able to make an adequate choice between two alternatives based on spatial information? Children of 20, 30, and 40 months of age were either presented with two objects with different cross-sections and one aperture, or one object and two different apertures. In each trial there was one object – aperture match and the task was to find that match and insert the object. All the children understood the task and tried to solve the problems but the 20-month-olds performed randomly and not even the 40-month-olds chose all the correct correspondences consistently. The results also showed that it is easier to choose between apertures than objects. This contrasts with the ability to solve the insertion problem once the choice was made. When choosing the correct object or aperture, the 40-month-olds inserted the triangle successfully in 85% of the cases. The boys and girls were equally good at solving the task, but the boys did it faster. The results show that making a choice adds significantly to the difficulty of solving spatial problems. It requires systematic examination of the objects and apertures involved, a working memory that can handle at least three items at a time, and an ability to inhibit an incorrect choice. Such executive functions are typically found in older preschool children but the present task shows that with an appropriate setup their development can be traced from a much earlier age.     

The perceptual origins of the abstract same/different concept in human infants

Very few experiments have studied the two item same/different relation in young human infants. This contrasts with an extensive animal literature. We tested young infants with two novel tasks designed specifically to provide convergent comparative measures. Each infant completed both tasks allowing an assessment of their understanding of the abstract concept rather than task-specific abilities. In a looking time task with photographic stimuli, we found that 8-month-olds are sensitive to the relation but 4-month-olds are not. The second task used an anticipatory eye movement paradigm with simple geometric stimuli. On each trial, two colored shapes appear and moved upwards behind an occluder. They reappeared on either the upper left or right depending on the relation between them. Infants at both ages learned and generalized the dependency but only for the different relation. These results show that human infants can learn the same/different concept but that, in strong continuity with animal results, their abilities are firmly grounded in perception.     

Priming 4.5-month-old infants to use height information by enhancing retrieval

How do infants select and use information that is relevant to the task at hand? Infants treat events that involve different spatial relations as distinct, and their selection and use of object information depends on the type of event they encounter. For example, 4.5-month-olds consider information about object height in occlusion events, but infants typically fail to do so in containment events until they reach the age of 7.5 months. However, after seeing a prime involving occlusion, 4.5-month-olds became sensitive to height information in a containment event (Experiment 1). The enhancement lasted over a brief delay (Experiment 2) and persisted even longer when infants were shown an additional occlusion prime but not an object prime (Experiment 3). Together, these findings reveal remarkable flexibility in visual representations of young infants and show that their use of information can be facilitated not by strengthening object representations per se but by strengthening their tendency to retrieve available information in the representations.     

Online processing of native and non-native phonemic contrasts in early bilinguals.

There is considerable debate about whether bilinguals can distinguish L2 phonemic contrasts as efficiently as first language speakers can. To test this issue, a group of highly proficient Spanish-dominant Catalan-Spanish bilinguals (who had been exposed to Catalan between the ages of 3 and 4, but who, previous to this age, had been exposed only to Spanish) and another group of Catalan-dominant bilinguals (who had been exposed to Catalan from birth) were compared in a gating task. We developed a variation of the gating procedure that included a two-alternative forced choice test after each fragment was played. The differences between the two alternatives consisted of phonemic contrasts existing in Catalan but not in Spanish. Four contrasts were tested: two vocalic contrasts [symbols: see text] and two consonantal contrasts [symbols: see text]. The results showed that Spanish-dominant bilinguals, even the subset who were able to make correct identifications at the last gate, systematically performed worse than the group of Catalan-dominant bilinguals, needing longer portions of the signal to be able to correctly identify the stimuli. We argue that these results support the hypothesis that L1 shapes the perceptual system at early stages of development in such a way that it will determine the perception of non-native phonemic contrasts, even if there is extensive and early exposure to L2.     

The development of infants’ use of property-poor sounds to individuate objects

There is evidence that infants as young as 4.5 months use property-rich but not property-poor sounds as the basis for individuating objects (Wilcox, Woods, Tuggy, & Napoli, 2006). The current research sought to identify the age at which infants demonstrate the capacity to use property-poor sounds. Using the task of Wilcox et al., infants aged 7 and 9 months were tested. The results revealed that 9- but not 7-month-olds demonstrated sensitivity to property-poor sounds (electronic tones) in an object individuation task. Additional results confirmed that the younger infants were sensitive to property-rich sounds (rattle sounds). These are the first positive results obtained with property-poor sounds in infants and lay the foundation for future research to identify the underlying basis for the developmental hierarchy favoring property-rich over property-poor sounds and possible mechanisms for change.     

Development of single/geminate obstruent discrimination by Japanese infants: early integration of durational and nondurational cues

The Japanese language has single/geminate obstruents characterized by durational difference in closure/frication as part of the phonemic repertoire used to distinguish word meanings. We first evaluated infants' abilities to discriminate naturally uttered single/geminate obstruents (/pata/ and /patta/) using the visual habituation-dishabituation method. The results revealed that 9.5-month-old Japanese infants were able to make this discrimination, t(21) = 2.119, p = .046, paired t test, whereas 4-month-olds were not, t(25) = 0.395, p = .696, paired t test. To examine how acoustic correlates (covarying cues) are associated with the contrast discrimination, we tested Japanese infants at 9.5 and 11.5 months of age with 3 combinations of natural and manipulated stimuli. The 11.5-month-olds were able to discriminate the naturally uttered pair (/pata/ vs. /patta/), t(20) = 4.680, p < .000, paired t test. Neither group discriminated the natural /patta/ from the manipulated /pata/ created from natural /patta/ tokens: For 9.5-month-olds, t(23) = 0.754, p = .458; for 11.5-month-olds, t(27) = 0.789, p = .437, paired t tests. Only the 11.5-month-olds discriminated the natural /pata/ and the manipulated /patta/ created from /pata/ tokens: For 9.5-month-olds, t(24) = 0.114, p = .910; for 11.5-month-olds, t(23) = 2.244, p = .035, paired t tests. These results suggest that Japanese infants acquire a sensitivity to contrasts of single/geminate obstruents by 9.5 months of age and that certain cues that covary with closure length either facilitate or interfere with contrast discrimination under particular conditions.     

Interactions in processing segmental and suprasegmental features of speech

A speeded classification task was used to determine the nature of the dependency relation that exists during the processing of a segmental distinction in vowel quality and a suprasegmental distinction in pitch (Experiment 1) or loudness (Experiment 2) in a consonantvowel syllable. In both experiments, evidence was found for a mutual, symmetrical dependency between the processes underlying the analysis of the segmental and suprasegmental information in the syllable. This type of interaction pattern contrasts with the pattern of unidirectional dependency previously found for the analysis of a consonantal distinction and a suprasegmental distinction, in which the analysis of the consonantal information was found to be dependent on the analysis of the suprasegmental information (e.g., Wood, 1974). Together with these earlier findings, the present results clearly indicate that the form of the interaction between processes responsible for segmental and suprasegmental analysis is a function of the type of segmental information being analyzed. Future research must determine whether the distinct interaction patterns found thus far for consonants and vowels are due to a difference in phonetic class per se, i.e., consonant vs. vowel, or to a difference in the nature of the acoustic information specifying the consonant and vowel.     

Twelve-month-olds privilege words over other linguistic sounds in an associative learning task

We examined whether 12-month-old infants privilege words over other linguistic stimuli in an associative learning task. Sixty-four infants were presented with sets of either word–object, communicative sound–object, or consonantal sound–object pairings until they habituated. They were then tested on a ‘switch’ in the sound to determine whether they were able to associate the word and/or sound with the novel objects. Infants associated words, but not communicative sounds or consonantal sounds, with novel objects. The results demonstrate that infants exhibit a preference for words over other linguistic stimuli in an associative word learning task. This suggests that by 12 months of age, infants have developed knowledge about the nature of an appropriate sound form for an object label and will privilege this form as an object label.     

Infants' ability to use luminance information to individuate objects

Recent research indicates that infants first use form and then surface features as the basis for individuating objects. However, very little is known about the underlying basis for infants' differential sensitivity to form than surface features. The present research assessed infants' sensitivity to luminance differences. Like other surface properties, luminance information typically reveals little about an object. Unlike other surface properties (e.g. pattern, color), the visual system can detect luminance differences at birth. The outcome of two experiments indicated that 11.5-month-olds, but not 7.5-month-olds, used luminance differences to individuate objects. These results suggest that it is not the age at which infants can detect a feature, but the nature of the information carried by the feature, that determines infants' capacity to individuate objects.     

Tracking irregular morphophonological dependencies in natural language: evidence from the acquisition of subject-verb agreement in French

This study examines French-learning infants’ sensitivity to grammatical non-adjacent dependencies involving subject-verb agreement (e.g., le/les garçons lit/lisent ‘the boy(s) read(s)’) where number is audible on both the determiner of the subject DP and the agreeing verb, and the dependency is spanning across two syntactic phrases. A further particularity of this subsystem of French subject-verb agreement is that number marking on the verb is phonologically highly irregular. Despite the challenge, the HPP results for 24- and 18-month-olds demonstrate knowledge of both number dependencies: between the singular determiner le and the non-adjacent singular verbal forms and between the plural determiner les and the non-adjacent plural verbal forms. A control experiment suggests that the infants are responding to known verb forms, not phonological regularities. Given the paucity of such forms in the adult input documented through a corpus study, these results are interpreted as evidence that 18-month-olds have the ability to extract complex patterns across a range of morphophonologically inconsistent and infrequent items in natural language.     

6- to 9-Month old infants discriminate vowel durations in variable speech contexts

Discriminating temporal relationships in speech is crucial for speech and language development. However, temporal variation of vowels is difficult to perceive for young infants when it is determined by surrounding speech sounds. Using a familiarization-discrimination paradigm, we show that English-learning 6- to 9-month-olds are capable of discriminating non-native acoustic vowel duration differences that systematically vary with subsequent consonantal durations. Furthermore, temporal regularity of stimulus presentation potentially makes the task easier for infants. These findings show that young infants can process fine-grained temporal aspects of speech sounds, a capacity that lays the foundation for building a phonological system of their ambient language(s).     

Infants learn about objects from statistics and people

In laboratory experiments, infants are sensitive to patterns of visual features that co-occur (e.g., Fiser & Aslin, 2002). Once infants learn the statistical regularities, however, what do they do with that knowledge? Moreover, which patterns do infants learn in the cluttered world outside of the laboratory? Across 4 experiments, we show that 9-month-olds use this sensitivity to make inferences about object properties. In Experiment 1, 9-month-old infants expected co-occurring visual features to remain fused (i.e., infants looked longer when co-occurring features split apart than when they stayed together). Forming such expectations can help identify integral object parts for object individuation, recognition, and categorization. In Experiment 2, we increased the task difficulty by presenting the test stimuli simultaneously with a different spatial layout from the familiarization trials to provide a more ecologically valid condition. Infants did not make similar inferences in this more distracting test condition. However, Experiment 3 showed that a social cue did allow inferences in this more difficult test condition, and Experiment 4 showed that social cues helped infants choose patterns among distractor patterns during learning as well as during test. These findings suggest that infants can use feature co-occurrence to learn about objects and that social cues shape such foundational learning in distraction-filled environments.     

Linguistic and cognitive abilities in infancy: when does language become a tool for categorization?

Infants' ability to form new object categories based on either visual or naming information alone was evaluated at two different ages (16 and 20 months) using an object manipulation task. Estimates of productive vocabulary size were also collected. Infants at both ages showed evidence of using visual information to categorize the objects, while only the older ones used naming information. Moreover, there was a correlation between vocabulary size and name-based categorization among the 20-month-olds. The present results establish that infants as young as 20 months can use the non-obvious cue of naming to categorize objects. The possibility of a link between this ability and lexical development is discussed.     

Infants discriminate manners and paths in non-linguistic dynamic events

Do 14- to 17-month-olds notice the paths and manners of motion events? English- and Spanish-learning infants were habituated to an animated motion event including a manner (e.g., spinning) and a path (e.g., over). They were then tested on four types of events that changed either the manner, the path, both, or neither component. Both English- and Spanish-learning infants attended to changes of manner and changes of path. Thus, infants from two different language communities proved sensitive to components of events that undergird relational term learning.     

Seeing pink elephants: fourteen-month-olds' interpretations of novel nouns and adjectives.

Words from different grammatical categories (e.g., nouns and adjectives) highlight different aspects of the same objects (e.g., object categories and object properties). Two experiments examine the acquisition of this phenomenon in 14-month-olds, asking whether infants can construe the very same set of objects (e.g., four purple animals) either as members of an object category (e.g., animals) or as embodying a salient object property (e.g., four purple things) and whether naming (with either count nouns or adjectives) influences infants' construals. Results suggest (1) that infants have begun to distinguish count nouns from adjectives, (2) that infants share with mature language-users an expectation that different grammatical forms highlight different aspects, and (3) that infants recruit these expectations when extending novel words. Further, these results suggest that an expectation linking count nouns to object categories emerges early in acquisition and supports the emergence of other word-to-world mappings.