What Develops in Infants’ Spatial Categorization? Korean Infants’ Categorization of Containment and Tight‐Fit Relations

Korean‐learning infants’ categorization of two spatial categories, one consistent and one inconsistent with the Korean semantic category of “kkita,” was examined. Infants of 10 months (n = 32) and 18 months (n = 49) were tested on their categorization of containment or tight fit spatial relations. At 10 months, infants only formed a category of containment, but at 18 months, their categorization of tight fit was significantly stronger than containment. The results suggest that Korean infants benefit from their language environment in forming a category of tight fit when the exemplars are perceptually diverse. In particular, infants’ language environment may bolster their ability to generalize across diverse exemplars to form abstract categorical representations of spatial relations.     

When less is more: how infants learn to form an abstract categorical representation of support

Two experiments explored how infants learn to form an abstract categorical representation of support (i.e., on) when habituated to few (i.e., 2) or many (i.e., 6) examples of the relation. When habituated to 2 pairs of objects in a support relation, 14-month-olds, but not 10-month-olds, formed the abstract spatial category (i.e., generalized the relation to novel objects). When habituated to 6 object pairs in a support relation, infants did not attend to the relation. The results indicate that infants learn to form an abstract spatial category of support between 10 and 14 months and that having fewer object pairs depicting this relation facilitates their acquisition of the abstract categorical representation.     

Prelinguistic Relational Concepts: Investigating Analogical Processing in Infants

This research asks whether analogical processing ability is present in human infants, using the simplest and most basic relation—the same–different relation. Experiment 1 (N = 26) tested whether 7‐ and 9‐month‐olds spontaneously detect and generalize these relations from a single example, as previous research has suggested. The attempted replication failed. Experiment 2 asked whether infants could abstract the relation via analogical processing (Experiment 2, N = 64). Indeed, with four exemplars, 7‐ and 9‐month‐olds could abstract the same–different relation and generalize it to novel pairs. Furthermore, prior experience with the objects disrupted learning. Facilitation from multiple exemplars and disruption by individual object salience are signatures of analogical learning. These results indicate that analogical ability is present by 7 months.     

Six-month-old infants' categorization of containment spatial relations

Six-month-old infants' ability to form an abstract category of containment was examined using a standard infant categorization task. Infants were habituated to 4 pairs of objects in a containment relation. Following habituation, infants were tested with a novel example of the familiar containment relation and an example of an unfamiliar relation. Results indicate that infants look reliably longer at the unfamiliar versus familiar relation, indicating that they can form a categorical representation of containment. A second experiment demonstrated that infants do not rely on object occlusion to discriminate containment from a support or a behind spatial relation. Together, the results indicate that by 6 months, infants can recognize a containment relation from different angles and across different pairs of objects.     

Parsing Items into Separate Categories: Developmental Change in Infant Categorization

Three experiments report developmental change in infants' tendency to parse exemplars into separate categories. In Experiment 1, a familiarization-novelty preference procedure was used. Fifty-four 4-, 7-, and 10-month-old infants were familiarized with members of two basic-level animal categories (cats and horses) and tested with novel members of the familiarized categories and with members of a third category (dogs). In Experiment 2, a habituation-dishabituation procedure was used. Forty-eight 7- and 10-month-old infants were habituated to examples of both male and female faces and tested with novel gender-typical and gender-ambiguous faces. In both experiments, 10-month-old infants appeared to form differentiated categories, whereas younger infants formed a single category to include the range of items presented during familiarization. Experiment 3 ruled out a priori stimulus preferences as an explanation for the 10-month findings in Experiment 2.     

Long-Term Memory for Context-Specific Category Information at Six Months

The ability of 6-month-old infants to remember a functional category acquired in a specific context was assessed in 3 experiments via an operant procedure in which infants learned to perform a specific action (a footkick) to activate an object suspended before them. In Experiment 1, infants trained with different exemplars in the same context transferred responding to a novel exemplar in the same but not a different context 24 hours later. Experiment 2 revealed that infants' reactivated memory of category training remained intact and context-specific after 3 weeks. In Experiment 3, a novel category exemplar was able to reactivate the forgotten memory of category training only in the encoding context. At 6 months, information about the place where categories are constructed is prerequisite for retrieval of a category concept from long-term memory. This requirement insures that early category concepts remain stable over relatively long periods.     

The Categorization of Above and Below Spatial Relations by Young Infants

3 experiments using the familiarization-novelty preference procedure were conducted to investigate whether 3-month-old infants could form categorical representations of the spatial relations above and below. In Experiment 1, one group of infants familiarized with exemplars depicting a dot in different positions above a horizontal bar displayed a subsequent visual preference for a novel category exemplar (dot below bar) that was paired with a familiar category exemplar (dot in novel position above bar). A second group of infants presented with exemplars in which the dot appeared in variable locations below the bar also responded preferentially to a novel category exemplar (dot above bar) when it was paired with a familiar category exemplar (dot in new position below bar). These preferences did not result from the salience of vertical up-down changes in dot position or the encoding of dot positions relative to an internal horizontal midline (Experiment 3) or from an inability to discriminate the members of each category (Experiment 2), but rather would seem to be a consequence of the ability to represent categorically the spatial relations above and below. The data provide evidence for early categorical organization in human spatial memory.     

What does it look like and what can it do? Category structure influences how infants categorize

Despite a large body of research demonstrating the kinds of categories to which infants respond, few studies have directly assessed how infants' categorization unfolds over time. Four experiments used a visual familiarization task to evaluate 10-month-old infants' (N = 98) learning of exemplars characterized by commonalities in appearance or function. When learning exemplars with a common function, infants initially responded to the common feature, apparently forming a category, and only learned the individual features with more extensive familiarization. When learning exemplars with a common appearance, infants initially learned the individual features and apparently only formed a category with more extensive familiarization. The results are discussed in terms of models of category learning.     

Learning to Individuate: The Specificity of Labels Differentially Impacts Infant Visual Attention

This study examined differences in visual attention as a function of label learning from 6 to 9 months of age. Before and after 3 months of parent‐directed storybook training with computer‐generated novel objects, event‐related potentials and visual fixations were recorded while infants viewed trained and untrained images (n = 23). Relative to a pretraining, a no‐training control group (n = 11), and to infants trained with category‐level labels (e.g., all labeled “Hitchel”), infants trained with individual‐level labels (e.g., “Boris,” “Jamar”) displayed increased visual attention and neural differentiation of objects after training.     

Infants’ Mapping of New Faces to New Voices

The ability to identify individuals by voice is fundamental for communication. However, little is known about the expectations that infants hold when learning unfamiliar voices. Here, the voice-learning skills of 4- and 8-month-olds (N = 53; 29 girls, 14 boys of various ethnicities) were tested using a preferential-looking task that involved audiovisual stimuli of their mothers and other unfamiliar women. Findings reveal that the expectation that novel voices map on to novel faces emerges between 4 and 8 months of age, and that infants can retain learning of face-voice pairings via nonostensive cues by 8 months of age. This study provides new insights about infants’ use of disambiguation and fast mapping in early voice learning.     

Biological Sensitivity to the Effects of Maternal Postpartum Depressive Symptoms on Children's Behavior Problems

Resting respiratory sinus arrhythmia (RSA) may confer infant susceptibility to the postpartum environment. Among infants with higher RSA, there may be a positive relation between depressive symptoms across the first 6 months postpartum (PPD) and later behavior problems, and toddlers’ dysregulation during mother–child interactions may partially explain the effects. Among a sample of low-income Mexican-American families, infant RSA (N = 322; 46% male) was assessed at 6 weeks of age; mothers (M_age = 27.8, SD = 6.5) reported PPD symptoms every 3 weeks from 6 to 24 weeks and infant behavior problems at 36 months. Dysregulation was observed at 24 months. PPD was positively associated with behavior problems only among infants with lower RSA; however, this relation was not mediated by dysregulation.     

Studies on the Formation of Perceptually Based Basic-Level Categories in Young Infants

A series of experiments examined the abilities of 3- and 4-month-old infants to form categorical representations to exemplars of natural kinds–cats and horses. These experiments also permitted assessment of the relative exclusivity of these representations—the extent to which they exclude exemplars from contrasting basic-level categories from the same superordinate category. We found that categorical representations could be formed for horses that excluded cats, zebras, and giraffes, and for cats that excluded horses and tigers but not female lions. Lions were, however, excluded from the representations of cats in 6- and 7-month-old infants. Evidence was also obtained for 2 a priori preferences for members of one category over another. The discussion examined the roles of similarity between the exemplars of the contrasting categories and those of the tested category on estimates of exclusivity and of spontaneous preferences on the formation and exclusivity of categorical representations.     

Cross‐Cultural Differences in Children's Beliefs About the Objectivity of Social Categories

The present study compared 5‐ and 10‐year‐old North American and Israeli children's beliefs about the objectivity of different categories (n = 109). Children saw picture triads composed of two exemplars of the same category (e.g., two women) and an exemplar of a contrasting category (e.g., a man). Children were asked whether it would be acceptable or wrong for people in a different country to consider contrasting exemplars to be the same kind. It was found that children from both countries viewed gender as objectively correct and occupation as flexible. The findings regarding race and ethnicity differed in the two countries, revealing how an essentialist bias interacts with cultural input in directing children's conceptualization of social groups.     

Young Infants’ Word Comprehension Given An Unfamiliar Talker or Altered Pronunciations

To understand spoken words, listeners must appropriately interpret co‐occurring talker characteristics and speech sound content. This ability was tested in 6‐ to 14‐months‐olds by measuring their looking to named food and body part images. In the new talker condition (n = 90), pictures were named by an unfamiliar voice; in the mispronunciation condition (n = 98), infants’ mothers “mispronounced” the words (e.g., nazz for nose). Six‐ to 7‐month‐olds fixated target images above chance across conditions, understanding novel talkers, and mothers’ phonologically deviant speech equally. Eleven‐ to 14‐months‐olds also understood new talkers, but performed poorly with mispronounced speech, indicating sensitivity to phonological deviation. Between these ages, performance was mixed. These findings highlight the changing roles of acoustic and phonetic variability in early word comprehension, as infants learn which variations alter meaning.     

Tactile training facilitates infants' ability to reach to targets on the body

This longitudinal study investigated the effect of experience with tactile stimulation on infants' ability to reach to targets on the body, an important adaptive skill. Infants were provided weekly tactile stimulation on eight body locations from 4 to 8 months of age (N = 11), comparing their ability to reach to the body to infants in a control group who did not receive stimulation (N = 10). Infants who received stimulation were more likely to successfully reach targets on the body than controls by 7 months of age. These findings indicate that tactile stimulation facilitates the development of reaching to the body by allowing infants to explore the sensorimotor correlations emerging from the stimulation.     

Sensitivity to Visual-Tactile Colocation on the Body Prior to Skilled Reaching in Early Infancy

Two experiments examined perceptual colocation of visual and tactile stimuli in young infants. Experiment 1 compared 4- (n = 15) and 6-month-old (n = 12) infants’ visual preferences for visual-tactile stimulus pairs presented across the same or different feet. The 4- and 6-month-olds showed, respectively, preferences for colocated and noncolocated conditions, demonstrating sensitivity to visual-tactile colocation on their feet. This extends previous findings of visual-tactile perceptual colocation on the hands in older infants. Control conditions excluded the possibility that both 6- (Experiment 1), and 4-month-olds (Experiment 2, n = 12) perceived colocation on the basis of an undifferentiated supramodal coding of spatial distance between stimuli. Bimodal perception of visual-tactile colocation is available by 4 months of age, that is, prior to the development of skilled reaching.     

Infant vocalizing and phenotypic outcomes in autism: Evidence from the first 2 years

Infant vocalizations are early-emerging communicative markers shown to be atypical in autism spectrum disorder (ASD), but few longitudinal, prospective studies exist. In this study, 23,850 infant vocalizations from infants at low (LR)- and high (HR)-risk for ASD (HR-ASD = 23, female = 3; HR-Neg = 35, female = 13; LR = 32, female = 10; 80% White; collected from 2007 to 2017 near Philadelphia) were analyzed at 6, 12, and 24 months. At 12 months, HR-ASD infants produced fewer vocalizations than HR-Neg infants. From 6 to 24 months, HR-Neg infants demonstrated steeper vocalization growth compared to HR-ASD and LR infants. Finally, among HR infants, vocalizing at 12 months was associated with language, social phenotype, and diagnosis at age 2. Infant vocalizing is an objective behavioral marker that could facilitate earlier detection of ASD.     

Comparing Automatic and Manual Measures of Parent–Infant Conversational Turns: A Word of Caution

The Language ENvironment Analysis system (LENA) records children’s language environment and provides an automatic estimate of adult–child conversational turn count (CTC). The present study compares LENA’s CTC estimate to manually coded CTC on a sample of 70 English-speaking infants recorded longitudinally at 6, 10, 14, 18, and 24 months of age. At each age, LENA’s CTC was significantly higher than manually coded CTC (all ps < .001, Cohen’s ds: 0.9–2.05), with the largest discrepancies between the two methods observed at younger ages. The Limits of Agreement Analyses confirm wide disagreements between the two methods, highlighting potential problems with automatic measurement of parent–infant verbal interaction. These findings suggest that future studies should validate LENA’s CTC estimates with manual coding.     

Does Temperament Underlie Infant Novel Food Responses?: Continuity of Approach–Withdrawal From 6 to 18 Months

This study investigated whether temperamental approach–withdrawal underlies infants' responses to novel foods. Data were drawn from a longitudinal study of mother–infant dyads (n = 136). Approach–withdrawal responses to novel foods and novel toys were coded when infants were 6 and 12 months of age. When infants were 18 months of age, approach–withdrawal behaviors, positive affect, and negative affect were used in a latent profile analysis to identify groups of toddlers who exhibited similar responses to novelty. As predicted, novel food and novel toy responses were concurrently associated at 12 months and followed a similar developmental pattern across the 1st year. Furthermore, novel food acceptance at 12 months of age, but not 6 months, predicted greater toddler approach.     

Infant Categorization of Path Relations During Dynamic Events

Fundamental to amassing a lexicon of relational terms (i.e., verbs, prepositions) is the ability to abstract and categorize spatial relations such as a figure (e.g., boy) moving along a path (e.g., around the barn). Three studies examine how infants learn to categorize path over changes in manner, or how an action is performed (e.g., running vs. crawling). Experiment 1 (n = 60) finds that 10‐ to 12‐month‐old English‐learning infants categorize a figure’s path. In Experiment 2 (n = 27) categorization is disrupted when the ground object is removed, suggesting the relation between figure and ground defines the path. Experiment 3 (n = 24) shows that language may be a mechanism guiding category formation. These studies suggest that English‐learning infants can categorize path, a component lexicalized in the world’s languages.