Infants’ perception of rhythm and tempo in unimodal and multimodal stimulation: A developmental test of the intersensory redundancy hypothesis

Research has demonstrated that young infants can detect a change in the tempo and the rhythm of an event when they experience the event bimodally (audiovisually), but not when they experience it unimodally (acoustically or visually). According to Bahrick and Lickliter (2000, 2002), intersensory redundancy available in bimodal, but not in unimodal, stimulation directs attention to the amodal properties of events in early development. Later in development, as infants become more experienced perceivers, attention becomes more flexible and can be directed toward amodal properties in unimodal and bimodal stimulation. The present study tested this developmental hypothesis by assessing the ability of older, more perceptually experienced infants to discriminate the tempo or rhythm of an event, using procedures identical to those in prior studies. The results indicated that older infants can detect a change in the rhythm and the tempo of an event following both bimodal (audiovisual) and unimodal (visual) stimulation. These results provide further support for the intersensory redundancy hypothesis and are consistent with a pattern of increasing specificity in perceptual development.     

The development of infant discrimination of affect in multimodal and unimodal stimulation: The role of intersensory redundancy

This research examined the developmental course of infants' ability to perceive affect in bimodal (audiovisual) and unimodal (auditory and visual) displays of a woman speaking. According to the intersensory redundancy hypothesis (L. E. Bahrick, R. Lickliter, & R. Flom, 2004), detection of amodal properties is facilitated in multimodal stimulation and attenuated in unimodal stimulation. Later in development, however, attention becomes more flexible, and amodal properties can be perceived in both multimodal and unimodal stimulation. The authors tested these predictions by assessing 3-, 4-, 5-, and 7-month-olds' discrimination of affect. Results demonstrated that in bimodal stimulation, discrimination of affect emerged by 4 months and remained stable across age. However, in unimodal stimulation, detection of affect emerged gradually, with sensitivity to auditory stimulation emerging at 5 months and visual stimulation at 7 months. Further temporal synchrony between faces and voices was necessary for younger infants' discrimination of affect. Across development, infants first perceive affect in multimodal stimulation through detecting amodal properties, and later their perception of affect is extended to unimodal auditory and visual stimulation. Implications for social development, including joint attention and social referencing, are considered.     

Intersensory redundancy educates selective attention in bobwhite quail embryos

We assessed whether exposure to amodal properties in bimodal stimulation (e.g. rhythm, rate, duration) could educate attention to amodal properties in subsequent unimodal stimulation during prenatal development. Bobwhite quail embryos were exposed to an individual bobwhite maternal call under several experimental and control conditions during the day prior to hatching. Experimental groups received redundant auditory and visual exposure to the temporal features of an individual maternal call followed by unimodal auditory exposure to the same call immediately or after a 2-hr or 4-hr delay. Control groups received (1) the same exposure but in the reverse sequence (unimodal --> redundant bimodal), (2) asynchronous bimodal --> unimodal, (3) only unimodal exposure, or (4) only bimodal exposure. All experimental groups showed a significant preference for the familiar maternal call over a novel maternal call when tested 2 days after hatching, whereas none of the control groups showed a significant preference for the familiar call. These results indicate that intersensory redundancy can direct attention to amodal properties in bimodal stimulation and educate attention to the same amodal properties in subsequent unimodal stimulation where no intersensory redundancy is available.     

Redundant amodal properties facilitate operant learning in 3-month-old infants

The current study examined the role redundant amodal properties play in an operant learning task in 3-month-old human infants. Prior studies have suggested that the presence of redundant amodal information facilitates detection and discrimination of amodal properties and potentially functions to influence general learning processes such as associative conditioning. The current study examined how human infants use redundant amodal information (visual and haptic) about the shape of an object to influence learning of an operant response. Infants learned to kick to move a mobile of cylinders while either holding a cylinder, a rectangular cube, or no object. Kick rate served as the dependent measure. The results showed that infants given matching redundant amodal properties (e.g., viewed cylinders while holding a cylinder) showed facilitated operant learning whereas infants given mismatching redundant amodal properties showed inhibited operant learning. These results support and extend the Intersensory Redundancy Hypothesis by demonstrating that amodal redundancy influences complex learning processes such as operant conditioning.     

Intersensory redundancy promotes visual rhythm discrimination in visually impaired infants

Infants’ attention is captured by the redundancy of amodal stimulation in multimodal objects and events. Evidence from this study demonstrates that intersensory redundancy can facilitate discrimination of rhythm changes presented in the visual modality alone in visually impaired infants, suggesting that multisensory rehabilitation strategies could prove helpful in this population.     

Intersensory redundancy facilitates prenatal perceptual learning in bobwhite quail (Colinus virginianus) embryos.

Information presented redundantly and in temporal synchrony across sensory modalities (intersensory redundancy) selectively recruits attention and facilitates perceptual learning in human infants. This comparative study examined whether intersensory redundancy also facilitates perceptual learning prenatally. The authors assessed quail (Colinus virginianus) embryos' ability to learn a maternal call when it was (a) unimodal, (b) concurrent but asynchronous with patterned light, or (c) redundant and synchronous with patterned light. Chicks' preference for the familiar over a novel maternal call was assessed 24 hr following hatching. Chicks receiving redundant, synchronous stimulation as embryos learned the call 4 times faster than those who received unimodal exposure. Chicks who received asynchronous bimodal stimulation showed no evidence of learning. These results provide the first evidence that embryos are sensitive to redundant, bimodal information and that it can facilitate learning during the prenatal period.     

Bimodal emotion congruency is critical to preverbal infants’ abstract rule learning

Extracting general rules from specific examples is important, as we must face the same challenge displayed in various formats. Previous studies have found that bimodal presentation of grammar‐like rules (e.g. ABA) enhanced 5‐month‐olds’ capacity to acquire a rule that infants failed to learn when the rule was presented with visual presentation of the shapes alone (circle‐triangle‐circle) or auditory presentation of the syllables (la‐ba‐la) alone. However, the mechanisms and constraints for this bimodal learning facilitation are still unknown. In this study, we used audio‐visual relation congruency between bimodal stimulation to disentangle possible facilitation sources. We exposed 8‐ to 10‐month‐old infants to an AAB sequence consisting of visual faces with affective expressions and/or auditory voices conveying emotions. Our results showed that infants were able to distinguish the learned AAB rule from other novel rules under bimodal stimulation when the affects in audio and visual stimuli were congruently paired (Experiments 1A and 2A). Infants failed to acquire the same rule when audio‐visual stimuli were incongruently matched (Experiment 2B) and when only the visual (Experiment 1B) or the audio (Experiment 1C) stimuli were presented. Our results highlight that bimodal facilitation in infant rule learning is not only dependent on better statistical probability and redundant sensory information, but also the relational congruency of audio‐visual information. A video abstract of this article can be viewed at https://m.youtube.com/watch?v=KYTyjH1k9RQ     

Developmental shift in the discrimination of vowel contrasts in bilingual infants: is the distributional account all there is to it?

A shift from language‐general to language‐specific sound discrimination abilities has been largely attested in different populations of infants during the second half of the first year of life; however, data are still scarce regarding bilingual populations. Previous research with 4‐, 8‐ and 12‐month‐old Catalan‐Spanish bilingual infants had offered evidence of a U‐shaped pattern in their ability to discriminate a language‐specific vowel contrast. This research explores monolingual and bilingual 4‐ and 8‐month‐olds’ capacities to discriminate two common vowel contrasts: /o–u/ and /e–u/. All groups succeeded except 8‐month‐old bilinguals tested on the phonetically close /o–u/ contrast. Discrimination was not facilitated when talker and token variability were reduced. A U‐shaped pattern was again found when data from an additional group of 12‐month‐olds were included. These results confirm bilinguals’ specific developmental pattern of perceptual reorganization for acoustically close vowels and challenge an interpretation merely based on a distributional account.     

Perceptual narrowing towards adult faces is a cross‐cultural phenomenon in infancy: a behavioral and near‐infrared spectroscopy study with Japanese infants

Recent data showed that, in Caucasian infants, perceptual narrowing occurs for own‐race adult faces between 3 and 9 months of age, possibly as a consequence of the extensive amount of social and perceptual experience accumulated with caregivers and/or other adult individuals of the same race of the caregiver. The neural correlates of this developmental process remain unexplored, and it is currently unknown whether perceptual tuning towards adult faces can be extended to other cultures. To this end, in the current study we tested the ability of 3‐ and 9‐month‐old Japanese infants to discriminate among adult and infant Asian faces in a visual familiarization task (Experiment 1), and compared 9‐month‐olds’ cerebral hemodynamic responses to adult and infant faces as measured by near‐infrared spectroscopy (NIRS) (Experiment 2). Results showed that 3‐month‐olds exhibit above‐chance discrimination of adult and infant faces, whereas 9‐month‐olds discriminate adult faces but not infant faces (Experiment 1). Moreover, adult faces, but not infant faces, induced significant increases in hemodynamic responses in the right temporal areas of 9‐month‐old infants. Overall, our data suggest that perceptual narrowing towards adult faces is a cross‐cultural phenomenon occurring between 3 and 9 months of age, and translates by 9 months of age into a right‐hemispheric specialization in the processing of adult faces.     

“Mummy,keep it steady”: phonetic variation shapes word learning at 15 and 17 months

Fifteen‐month‐olds have difficulty detecting differences between novel words differing in a single vowel. Previous work showed that Australian English (AusE) infants habituated to the word‐object pair DEET detected an auditory switch to DIT and DOOT in Canadian English (CanE) but not in their native AusE (Escudero et al., 2014 ). The authors speculated that this may be because the vowel inherent spectral change variation (VISC) in AusE DEET is larger than in CanE DEET. We investigated whether VISC leads to difficulty in encoding phonetic detail during early word learning, and whether this difficulty dissipates with age. In Experiment 1, we familiarized AusE‐learning 15‐month‐olds to AusE DIT, which contains smaller VISC than AusE DEET. Unlike infants familiarized with AusE DEET (Escudero et al., 2014 ), infants detected a switch to DEET and DOOT. In Experiment 2, we familiarized AusE‐learning 17‐month‐olds to AusE DEET. This time, infants detected a switch to DOOT, and marginally detected a switch to DIT. Our acoustic analysis showed that AusE DEET and DOOT are differentiated by the second vowel formant, while DEET and DIT can only be distinguished by their changing dynamic properties throughout the vowel trajectory. Thus, by 17 months, AusE infants can encode highly dynamic acoustic properties, enabling them to learn the novel vowel minimal pairs that are difficult at 15 months. These findings suggest that the development of word learning is shaped by the phonetic properties of the specific word minimal pair.     

Object individuation and event mapping: developmental changes in infants’ use of featural information

The present research examined the development of 4.5‐ to 7.5‐month‐old infants’ ability to map different‐features occlusion events using a simplified event‐mapping task. In this task, infants saw a different‐features (i.e. egg‐column) event followed by a display containing either one object or two objects. Experiments 1 and 2 assessed infants’ ability to judge whether the egg‐column event was consistent with a subsequent one‐column display. Experiments 3 and 4 examined infants’ ability to judge whether the objects seen in the egg‐column event and those seen in a subsequent display were consistent in their featural composition. At 7.5 and 5.5 months, but not at 4.5 months, the infants successfully mapped the egg‐column event onto the one‐column display. However, the 7.5‐ and 5.5‐month‐olds differed in whether they mapped the featural properties of those objects. Whereas the 7.5‐month‐olds responded as if they expected to see two specific objects, an egg and a column, in the final display the 5.5‐month‐olds responded as if they simply expected to see ‘two objects’. Additional results revealed, however, that when spatiotemporal information specified the presence of two objects, 5.5‐month‐olds succeeded at tagging the objects as being featurally distinct, although they still failed to attach more specific information about what those differences were. Reasons for why the younger infants had difficulty integrating featural information into their object representations were discussed.     

The effect of eye size on discriminating faces: Can infants recognize facial uncanniness?

Infants' ability to recognize uncanny human faces increases during the first year of life. In turn, their ability to recognize faces of other species declines at almost the same period (perceptual narrowing). In the current study, we aimed to clarify the relationship between the perception of uncanniness of faces and perceptual narrowing in infants and adults. We used the “uncanny valley task,” in which the participants were required to discriminate the faces of humans and monkeys by different eye size. Results showed that 3‐ to 5‐month‐old infants could not discriminate either monkey or human faces by eye size, whereas 6‐ to 8‐month olds could. Adults showed higher discrimination performance for human than monkey faces and perceived the human faces with extremely large or small eyes as exceedingly eerie. Our results suggest that perception of uncanniness of faces is formed after perceptual narrowing.     

Categorization,categorical perception,and asymmetry in infants’ representation of face race

The present study examined whether 6‐ and 9‐month‐old Caucasian infants could categorize faces according to race. In Experiment 1, infants were familiarized with different female faces from a common ethnic background (i.e. either Caucasian or Asian) and then tested with female faces from a novel race category. Nine‐month‐olds were able to form discrete categories of Caucasian and Asian faces. However, 6‐month‐olds did not form discrete categories of faces based on race. In Experiment 2, a second group of 6‐ and 9‐month‐olds was tested to determine whether they could discriminate between different faces from the same race category. Results showed that both age groups could only discriminate between different faces from the own‐race category of Caucasian faces. The findings of the two experiments taken together suggest that 9‐month‐olds formed a category of Caucasian faces that are further differentiated at the individual level. In contrast, although they could form a category of Asian faces, they could not discriminate between such other‐race faces. This asymmetry in category formation at 9 months (i.e. categorization of own‐race faces vs. categorical perception of other‐race faces) suggests that differential experience with own‐ and other‐race faces plays an important role in infants’ acquisition of face processing abilities.     

Neural correlates of infant accent discrimination: an fNIRS study

The present study investigated the neural correlates of infant discrimination of very similar linguistic varieties (Quebecois and Parisian French) using functional Near InfraRed Spectroscopy. In line with previous behavioral and electrophysiological data, there was no evidence that 3‐month‐olds discriminated the two regional accents, whereas 5‐month‐olds did, with the locus of discrimination in left anterior perisylvian regions. These neuroimaging results suggest that a developing language network relying crucially on left perisylvian cortices sustains infants’ discrimination of similar linguistic varieties within this early period of infancy.     

汉语婴儿词汇学习的注意偏好

婴儿的动、名词词类学习存在跨文化差异,但是很少研究从注意偏好角度解释这类差异。本研究利用习惯化范式考察汉语婴儿在6-8个月和17-19个月时对事件中人物,动作和物体的区分。结果发现,6-8个月的婴儿仅能区分动作变化,对人物和物体无法区分,而17-19个月的婴儿对三类变化均可以区分。本研究提供了婴儿早期注意偏好发展的实验依据,同时为儿童早期单词获得提供了新的理论基础。     

Something old,something new: a developmental transition from familiarity to novelty preferences with hidden objects

Novelty seeking is viewed as adaptive, and novelty preferences in infancy predict cognitive performance into adulthood. Yet 7‐month‐olds prefer familiar stimuli to novel ones when searching for hidden objects, in contrast to their strong novelty preferences with visible objects ( Shinskey & Munakata, 2005 ). According to a graded representations perspective on object knowledge, infants gradually develop stronger object representations through experience, such that representations of familiar objects can be better maintained, supporting greater search than with novel objects. Object representations should strengthen with further development to allow older infants to shift from familiarity to novelty preferences with hidden objects. The current study tested this prediction by presenting 24 11‐month‐olds with novel and familiar objects that were sometimes visible and sometimes hidden. Unlike 7‐month‐olds, 11‐month‐olds showed novelty preferences with both visible and hidden objects. This developmental shift from familiarity to novelty preference with hidden objects parallels one that infants show months earlier with perceptible stimuli, but the two transitions may reflect different underlying mechanisms. The current findings suggest both change and continuity in the adaptive development of object representations and associated cognitive processes.     

Discrimination of Lexical Tones in the First Year of Life

In the current study, we examined the developmental course of the perception of non‐native tonal contrast. We tested 4, 6 and 12‐month‐old Dutch infants on their discrimination of Chinese low‐rising tone and low‐dipping tone using the visual fixation paradigm. The infants were tested in two conditions that differed in terms of degree of variability. The 4‐month‐olds did not show discrimination effect in either condition. The 6‐ and 12‐month‐old infants, however, discriminated the tones in both conditions. The improvement of perception might be the result of cognitive development carried over from learning the native phonology. Infants can become better listeners in general in the first year of life, as well as get cognitively better equipped in dealing with the variable input in speech in general. Copyright © 2015 John Wiley & Sons, Ltd.     

One‐year‐old infants use teleological representations of actions productively

Two experiments investigated whether infants represent goal‐directed actions of others in a way that allows them to draw inferences to unobserved states of affairs (such as unseen goal states or occluded obstacles). We measured looking times to assess violation of infants' expectations upon perceiving either a change in the actions of computer‐animated figures or in the context of such actions. The first experiment tested whether infants would attribute a goal to an action that they had not seen completed. The second experiment tested whether infants would infer from an observed action the presence of an occluded object that functions as an obstacle. The looking time patterns of 12‐month‐olds indicated that they were able to make both types of inferences, while 9‐month‐olds failed in both tasks. These results demonstrate that, by the end of the first year of life, infants use the principle of rational action not only for the interpretation and prediction of goal‐directed actions, but also for making productive inferences about unseen aspects of their context. We discuss the underlying mechanisms that may be involved in the developmental change from 9 to 12 months of age in the ability to infer hypothetical (unseen) states of affairs in teleological action representations.     

Precursors of a theory of mind: A longitudinal study

The study examined whether the pointing gesture and intentional understanding abilities at 12 and 15 months of age predict the later understanding of perception and intention, as well as the ability to explain others' actions in a psychological way at 39 months of age. Thirty‐five infants (18 girls) were administered pointing and intention‐understanding tasks at the age of 12 and 15 months. Children were again evaluated at the age of 39 months with perception and intention tasks, and a psychological explanation task. Results showed that only 12‐month‐olds' comprehension of the pointing gesture with an imperative motive contributed to the prediction of later understanding of perception and mentalistic explanations of actions. Moreover, the ability of 12‐ and 15‐month‐olds to understand intentions contributed to the prediction of later preschool understanding of perceptions and intentions. These results indicate that a developmental trajectory in children's understanding of mental states from infancy to childhood is present, but depends on the level of engagement and communication that are required to perform these tasks.     

Sound induces perceptual reorganization of an ambiguous motion display in human infants

Adults who watch an ambiguous visual event consisting of two identical objects moving toward, through, and away from each other and hear a brief sound when the objects overlap report seeing visual bouncing. We conducted three experiments in which we used the habituation/test method to determine whether these illusory effects might emerge early in development. In Experiments 1 and 3 we tested 4‐, 6‐ and 8‐month‐old infants’ discrimination between an ambiguous visual display presented together with a sound synchronized with the objects’ spatial coincidence and the identical visual display presented together with a sound no longer synchronized with coincidence. Consistent with illusory perception, the 6‐ and 8‐month‐old, but not the 4‐month‐old, infants responded to these events as different. In Experiment 2 infants were habituated to the ambiguous visual display together with a sound synchronized with the objects’ coincidence and tested with a physically bouncing object accompanied by the sound at the bounce. Consistent with illusory perception again, infants treated these two events as equivalent by not exhibiting response recovery. The developmental emergence of this intersensory illusion at 6 months of age is hypothesized to reflect developmental changes in object knowledge and attentional mechanisms.