Scott P. Johnson’s research while affiliated with University of California, Los Angeles and other places

Infants prefer infant-directed (ID) speech. Concerning talking faces, previous research showed that 3-and 5-month-olds prefer faces that produce native ID than native adult-directed (AD) speech, regardless of background speech being ID, AD or silent. Here, we explored whether infants also show a preference for non-native ID speech. We presented 3-and 6-month-old infants with pairs of talking faces, one producing non-native ID speech and the other non-native AD speech, either in silence (Experiment 1) or accompanied by non-native ID or AD background speech (Experiment 2). Results from Experiment 1 showed an overall preference for the silent ID talking faces across both age groups, suggesting a reliance on cross-linguistic, potentially universal cues for this preference. However, Experiment 2 showed that preference for ID faces was disrupted at 3 months when auditory speech was present (ID or AD). At 6 months, infants maintained a preference for ID talking faces, but only when accompanied by ID speech. These findings show that auditory non-native speech interferes with infants' processing of ID talking faces. They also suggest that by 6 months, infants start associating ID features from faces and voices irrespective of language familiarity, suggesting that infants' ID preference may be universal and amodal.

Mental rotation (MR) is an important feature of spatial cognition invoking mental imagery of an object’s appearance when viewed from a new orientation. Prior studies have revealed evidence of MR in infants, including a sex difference similar to that detected in older populations. Some of these studies used visual habituation methods whereby infants were familiarized with an object rotating through a 240° angle, followed by test trials showing either the habituation object or a mirror image object rotating through the previously unseen 120° angle. Significantly longer looking at either of these objects was taken to reflect infants’ ability to recognize the habituation object even when seen from a novel viewpoint, suggesting the capacity for MR. However, these infants’ responses could, in theory, be explained with reference to perceptual discrimination rather than MR, because the views of the habituation and test objects were very similar in some video frames. In the current study, we observed a diverse population of 5-month-olds (24 females, 24 males) for evidence of MR through 30° of arc. In this more challenging test, our stimuli left a 30° gap angle between critical video frames representing the habituation and test objects. Consistent with earlier reports, we found that relative to female infants, male infants looked significantly longer at the mirror image test stimulus immediately following habituation. These results add to an emerging consensus that some young infants are capable of MR, and that male and female infants on average behave differently in this type of MR task.

The communication of emotion is dynamic and occurs across multiple channels, such as facial expression and tone of voice. When cues are in conflict, interpreting emotion can become challenging. Here, we examined the effects of incongruent emotional cues on toddlers’ interpretation of emotions. We presented 33 children (22–26 months, Mage = 23.8 months, 15 female) with side‐by‐side images of faces along with sentences spoken in a tone of voice that conflicted with semantic content. One of the two faces matched the emotional tone of the audio, whereas the other matched the semantic content. For both congruent and incongruent trials, toddlers showed no overall looking preference to either type of face stimuli. However, during the second exposure to the sentences of incongruent trials, older children tended to look longer to the face matching semantic content when listening to happy vs. angry content. Results inform our understanding of the early development of complex emotion understanding.

Individuals with autism spectrum disorder (ASD) tend to experience greater difficulties with social communication and sensory information processing. Of particular interest in ASD biomarker research is the study of visual attention, effectively quantified in eye tracking (ET) experiments. Eye tracking offers a powerful, safe, and feasible platform for gaining insights into attentional processes by measuring moment-by-moment gaze patterns in response to stimuli. Even though recording is done with millisecond granularity, analyses commonly collapse data across trials into variables such as proportion time spent looking at a region of interest (ROI). In addition, looking times in different ROIs are typically analyzed separately. We propose a novel multivariate functional outcome that carries proportion looking time information from multiple regions of interest jointly as a function of trial type, along with a novel constrained multivariate functional principal components analysis procedure to capture the variation in this outcome. The method incorporates the natural constraint that the proportion looking times from the multiple regions of interest must sum up to one. Our approach is motivated by the Activity Monitoring task, a social-attentional assay within the ET battery of the Autism Biomarkers Consortium for Clinical Trials (ABC-CT). Application of our methods to the ABC-CT data yields new insights into dominant modes of variation of proportion looking times from multiple regions of interest for school-age children with ASD and their typically developing (TD) peers, as well as richer analysis of diagnostic group differences in social attention.

The Selective Social Attention (SSA) task is a brief eye‐tracking task involving experimental conditions varying along socio‐communicative axes. Traditionally the SSA has been used to probe socially‐specific attentional patterns in infants and toddlers who develop autism spectrum disorder (ASD). This current work extends these findings to preschool and school‐age children. Children 4‐ to 12‐years‐old with ASD (N = 23) and a typically‐developing comparison group (TD; N = 25) completed the SSA task as well as standardized clinical assessments. Linear mixed models examined group and condition effects on two outcome variables: percent of time spent looking at the scene relative to scene presentation time (%Valid), and percent of time looking at the face relative to time spent looking at the scene (%Face). Age and IQ were included as covariates. Outcome variables' relationships to clinical data were assessed via correlation analysis. The ASD group, compared to the TD group, looked less at the scene and focused less on the actress' face during the most socially‐engaging experimental conditions. Additionally, within the ASD group, %Face negatively correlated with SRS total T‐scores with a particularly strong negative correlation with the Autistic Mannerism subscale T‐score. These results highlight the extensibility of the SSA to older children with ASD, including replication of between‐group differences previously seen in infants and toddlers, as well as its ability to capture meaningful clinical variation within the autism spectrum across a wide developmental span inclusive of preschool and school‐aged children. The properties suggest that the SSA may have broad potential as a biomarker for ASD.

Sensory Individuals: Unimodal and Multimodal Perspectives provides an interdisciplinary, well-balanced, and comprehensive look at different aspects of unisensory and multisensory objects, using both nuanced philosophical analysis and informed empirical work. The research presented in this book represents the field's progression from treating neural sensory processes as primarily modality-specific towards its current state of the art, according to which perception, and its supporting neural processes, are multi-modal, modality-independent, meta-modal, and task-dependent. Even within such approaches sensory stimuli, properties, brain activations, and corresponding perceptual phenomenology can still be characterized in a modality-specific way. The book examines the basic building blocks of human perception, and whether they are best understood as sense modality-dependent units of different forms or multimodal perceptual objects. The book combines a variety of innovative and integrative angles to explore the topic and acts as a catalyst for an increasingly diverse field of research, which is in an exciting phase of growth and advancement. New questions are arising as quickly as they are being answered, and the collection Sensory Individuals provides an original and up-to-date addition to the field.

Statistical learning relies on detecting the frequency of co-occurrences of items and has been proposed to be crucial for a variety of learning problems, notably to learn and memorize words from fluent speech. Endress and Johnson (2021) (hereafter EJ) recently showed that such results can be explained based on simple memory-less correlational learning mechanisms such as Hebbian Learning. Tovar and Westermann (2022) (hereafter TW) reproduced these results with a different Hebbian model. We show that the main differences between the models are whether temporal decay acts on both the connection weights and the activations (in TW) or only on the activations (in EJ), and whether interference affects weights (in TW) or activations (in EJ). Given that weights and activations are linked through the Hebbian learning rule, the networks behave similarly. However, in contrast to TW, we do not believe that neurophysiological data are relevant to adjudicate between abstract psychological models with little biological detail. Taken together, both models show that different memory-less correlational learning mechanisms provide a parsimonious account of Statistical Learning results. They are consistent with evidence that Statistical Learning might not allow learners to learn and retain words, and Statistical Learning might support predictive processing instead.

Eye tracking (ET) experiments commonly record the continuous trajectory of a subject’s gaze on a two-dimensional screen throughout repeated presentations of stimuli (referred to as trials). Even though the continuous path of gaze is recorded during each trial, commonly derived outcomes for analysis collapse the data into simple summaries, such as looking times in regions of interest, latency to looking at stimuli, number of stimuli viewed, number of fixations, or fixation length. In order to retain information in trial time, we utilize functional data analysis (FDA) for the first time in literature in the analysis of ET data. More specifically, novel functional outcomes for ET data, referred to as viewing profiles, are introduced that capture the common gazing trends across trial time which are lost in traditional data summaries. Mean and variation of the proposed functional outcomes across subjects are then modeled using functional principal component analysis. Applications to data from a visual exploration paradigm conducted by the Autism Biomarkers Consortium for Clinical Trials showcase the novel insights gained from the proposed FDA approach, including significant group differences between children diagnosed with autism and their typically developing peers in their consistency of looking at faces early on in trial time.

Language has been proposed as a potential mechanism for young children's developing understanding of emotion. However, much remains unknown about this relation at an individual difference level. The present study investigated 15- to 18-month-old infants' perception of emotions across multiple pairs of faces. Parents reported their child's productive vocabulary, and infants participated in a non-linguistic emotion perception task via an eye tracker. Infant vocabulary did not predict nonverbal emotion perception when accounting for infant age, gender, and general object perception ability (β = -0.15, p = .300). However, we observed a gender difference: Only girls' vocabulary scores related to nonverbal emotion perception when controlling for age and general object perception ability (β = 0.42, p = .024). Further, boys showed a stronger preference for the novel emotion face vs. girls (t(48) = 2.35, p = .023, d= 0.67). These data suggest that pathways of processing emotional information (e.g., using language vs visual information) may differ for girls and boys in late infancy.