Detection of Modality-Specific Properties in Unimodal and Bimodal Events during Prenatal Development

Predictions of the Intersensory Redundancy Hypothesis (IRH) state that early in development information presented to a single sense modality (unimodal) selectively recruits attention to and enhances perceptual learning of modality-specific properties of stimulation at the expense of amodal properties, while information presented redundantly across two or more modalities (bimodal) results in enhanced perceptual learning of amodal properties. The present study explored these predictions during prenatal development by assessing bobwhite quail embryos’ detection of pitch, a modality-specific property, under conditions of unimodal and redundant bimodal stimulation. Chicks’ postnatal auditory preferences between the familiarized call and the same call with altered pitch were assessed following hatching. Unimodally-exposed chicks significantly preferred the familiarized call over the pitch-modified call, whereas bimodally-exposed chicks did not prefer the familiar call over the pitch-modified call. Results confirm IRH predictions, demonstrating unimodal exposure facilitates learning of modality-specific properties, whereas redundant bimodal stimulation interferes with learning of modality-specific properties

Tests of the Intersensory Redundancy Hypothesis across Early Postnatal Development

The Intersensory Redundancy Hypothesis (IRH; Bahrick & Lickliter, 2000, 2002, 2012) predicts that early in development information presented to a single sense modality will selectively recruit attention to modality-specific properties of stimulation and facilitate learning of those properties at the expense of amodal properties (unimodal facilitation). Vaillant (2010) demonstrated that bobwhite quail chicks prenatally exposed to a maternal call alone (unimodal stimulation) are able to detect a pitch change, a modality-specific property, in subsequent postnatal testing between the familiarized call and the same call with altered pitch. In contrast, chicks prenatally exposed to a maternal call paired with a temporally synchronous light (redundant audiovisual stimulation) were unable to detect a pitch change. According to the IRH (Bahrick & Lickliter, 2012), as development proceeds and the individual’s perceptual abilities increase, the individual should detect modality-specific properties in both nonredundant, unimodal and redundant, bimodal conditions. However, when the perceiver is presented with a difficult task, relative to their level of expertise, unimodal facilitation should become evident. The first experiment of the present study exposed bobwhite quail chicks 24 hr after hatching to unimodal auditory, nonredundant audiovisual, or redundant audiovisual presentations of a maternal call for 10min/hr for 24 hours. All chicks were subsequently tested 24 hr after the completion of the stimulation (72 hr following hatching) between the familiarized maternal call and the same call with altered pitch. Chicks from all experimental groups (unimodal, nonredundant audiovisual, and redundant audiovisual exposure) significantly preferred the familiarized call over the pitch-modified call. The second experiment exposed chicks to the same exposure conditions, but created a more difficult task by narrowing the pitch range between the two maternal calls with which they were tested. Chicks in the unimodal and nonredundant audiovisual conditions demonstrated detection of the pitch change, whereas the redundant audiovisual exposure group did not show detection of the pitch change, providing evidence of unimodal facilitation. These results are consistent with predictions of the IRH and provide further support for the effects of unimodal facilitation and the role of task difficulty across early development

Social touch and human development.

Social touch is a powerful force in human development, shaping social reward, attachment, cognitive, communication, and emotional regulation from infancy and throughout life. In this review, we consider the question of how social touch is defined from both bottom-up and top-down perspectives. In the former category, there is a clear role for the C-touch (CT) system, which constitutes a unique submodality that mediates affective touch and contrasts with discriminative touch. Top-down factors such as culture, personal relationships, setting, gender, and other contextual influences are also important in defining and interpreting social touch. The critical role of social touch throughout the lifespan is considered, with special attention to infancy and young childhood, a time during which social touch and its neural, behavioral, and physiological contingencies contribute to reinforcement-based learning and impact a variety of developmental trajectories. Finally, the role of social touch in an example of disordered development -autism spectrum disorder-is reviewed

The Development of Attentional Biases for Faces in Infancy: A Developmental Systems Perspective

We present an integrative review of research and theory on major factors involved in the early development of attentional biases to faces. Research utilizing behavioral, eye-tracking, and neuroscience measures with infant participants as well as comparative research with animal subjects are reviewed. We begin with coverage of research demonstrating the presence of an attentional bias for faces shortly after birth, such as newborn infants’ visual preference for face-like over non-face stimuli. The role of experience and the process of perceptual narrowing in face processing are examined as infants begin to demonstrate enhanced behavioral and neural responsiveness to mother over stranger, female over male, own- over other-race, and native over non-native faces. Next, we cover research on developmental change in infants’ neural responsiveness to faces in multimodal contexts, such as audiovisual speech. We also explore the potential influence of arousal and attention on early perceptual preferences for faces. Lastly, the potential influence of the development of attention systems in the brain on social-cognitive processing is discussed. In conclusion, we interpret the findings under the framework of Developmental Systems Theory, emphasizing the combined and distributed influence of several factors, both internal (e.g., arousal, neural development) and external (e.g., early social experience) to the developing child, in the emergence of attentional biases that lead to enhanced responsiveness and processing of faces commonly encountered in the native environment

Dysconnection in schizophrenia: from abnormal synaptic plasticity to failures of self-monitoring

Over the last 2 decades, a large number of neurophysiological and neuroimaging studies of patients with schizophrenia have furnished in vivo evidence for dysconnectivity, ie, abnormal functional integration of brain processes. While the evidence for dysconnectivity in schizophrenia is strong, its etiology, pathophysiological mechanisms, and significance for clinical symptoms are unclear. First, dysconnectivity could result from aberrant wiring of connections during development, from aberrant synaptic plasticity, or from both. Second, it is not clear how schizophrenic symptoms can be understood mechanistically as a consequence of dysconnectivity. Third, if dysconnectivity is the primary pathophysiology, and not just an epiphenomenon, then it should provide a mechanistic explanation for known empirical facts about schizophrenia. This article addresses these 3 issues in the framework of the dysconnection hypothesis. This theory postulates that the core pathology in schizophrenia resides in aberrant N-methyl-D-aspartate receptor (NMDAR)–mediated synaptic plasticity due to abnormal regulation of NMDARs by neuromodulatory transmitters like dopamine, serotonin, or acetylcholine. We argue that this neurobiological mechanism can explain failures of self-monitoring, leading to a mechanistic explanation for first-rank symptoms as pathognomonic features of schizophrenia, and may provide a basis for future diagnostic classifications with physiologically defined patient subgroups. Finally, we test the explanatory power of our theory against a list of empirical facts about schizophrenia

Olfaction scaffolds the developing human from neonate to adolescent and beyond

The impact of the olfactory sense is regularly apparent across development. The foetus is bathed in amniotic fluid that conveys the mother’s chemical ecology. Transnatal olfactory continuity between the odours of amniotic fluid and milk assists in the transition to nursing. At the same time, odours emanating from the mammary areas provoke appetitive responses in newborns. Odours experienced from the mother’s diet during breastfeeding, and from practices such as pre-mastication, may assist in the dietary transition at weaning. In parallel, infants are attracted to and recognise their mother’s odours; later, children are able to recognise other kin and peers based on their odours. Familiar odours, such as those of the mother, regulate the child’s emotions, and scaffold perception and learning through non-olfactory senses. During adolescence, individuals become more sensitive to some bodily odours, while the timing of adolescence itself has been speculated to draw from the chemical ecology of the family unit. Odours learnt early in life and within the family niche continue to influence preferences as mate choice becomes relevant. Olfaction thus appears significant in turning on, sustaining and, in cases when mother odour is altered, disturbing adaptive reciprocity between offspring and caregiver during the multiple transitions of development between birth and adolescence

A Multi-method Analysis of Intersensory Perception of Social Information in Children and Adolescents with Autism Spectrum Disorder

The present study investigated the intersensory processing deficit for social stimuli in individuals with ASD compared to age- and cognitive-ability matched typically developing peers. This deficit was theorized to account (at least partially) for cascading impairments in attention and autism symptomatology across development. The primary goal was to isolate the social and linguistic properties of intersensory (audio-visual) processing using a manipulation of temporal synchrony. In Study One, a multi-method analysis of looking time and proportion of efficient gaze patterns using eye-tracking data from a behavioural task was used. Results provided evidence of a difference in intersensory processing specifically for social stimuli in children with ASD that does not appear to be solely attributable to a deficit in processing faces, language, or body movement. The secondary goal of the project was to provide a better understanding of variables that impact and are impacted by intersensory processing. In Study Two the strength and direction of the relationship between intersensory processing and developmental, diagnostic, and attention variables was assessed. Results showed that impaired intersensory processing for social information appears to be associated with cascading consequences across development including some of the core impairments in Autism Spectrum Disorder: disrupted sensory processing, social-communication disability, and slower attentional disengagement. In summary, results of Study One and Study Two are best understood as a specific cognitive-perceptual deficit in social orienting and are consistent with the Intersensory Redundency Hypothesis. The observed intersensory processing differences between groups may be impacted by dysfunctional intersensory integration wherein the most general amodal property, temporal synchrony, is misprocessed at early stages, disrupting selective attention and early social orienting. This impairment impacts the cascading cycle of perception, learning, memory, attention and so on and contributes to core sensory and social-communication impairments associated with Autism Spectrum Disorder

The Role of Auditory-Visual Synchrony in Capture of Attention and Induction of Attentional State in Infancy

This study was designed to examine the types of events that are most effective in capturing infant attention and whether these attention-getting events also effectively elicit an attentional state and facilitate perception and learning. Despite the frequent use of attention-getters (AGs) - presenting an attention-grabbing event between trials to redirect attention and reduce data loss due to fussiness - relatively little is known about the influence of AGs on attentional state. A recent investigation revealed that the presentation of AGs not only captures attention, but also produces heart rate decelerations during habituation and faster dishabituation in a subsequent task, indicating changes in the state of sustained attention and enhanced stimulus processing (Domsch, Thomas, & Lohaus, 2010). Attention-getters are often multimodal, dynamic, and temporally synchronous; such highly redundant properties generally guide selective attention and are thought to coordinate multisensory information in early development. In the current study, 4-month-old infants were randomly assigned to one of three attention-getter AG conditions: synchronous AG, asynchronous AG, and no AG. Following the AG, infants completed a discrimination task with a partial-lag design, which allowed for the assessment of infants' ability to discriminate between familiar and novel stimuli while controlling for spontaneous recovery. Analyses indicated that the AG condition captured and induced an attentional state, regardless of the presence of temporal synchrony. Although the synchronous and asynchronous AG conditions produced similar patterns of attention in the AG session, during familiarization infants in the asynchronous AG condition showed a pattern of increasing HR across the task and had higher overall HR compared to the synchronous AG and no AG conditions. Implications of the effect of attention-getters and temporal synchrony on infant performance are discussed