The eye of the retriever: developing episodic memory mechanisms in preverbal infants assessed through pupil dilation

Studying memory in infants can be challenging, as they cannot express their subjective recollection verbally. In this study we use a novel method with which we can assess episodic recognition memory through pupillometry, using identical procedures and stimuli for infants and adults. In three experiments of 4‐ and 7‐month‐old infants, and adults we show that the adult pupillary response is larger to previously seen than to never seen items (old/new effect). Pupil dilations index subjective memory experience in adults, producing distinct pupil dilations to items judged as remembered, familiar, and new, regardless of actual previous exposure (Experiment 1). Seven‐month‐old infants demonstrate a clear pupillary old/new effect, very similar to that of adults (Experiment 2), whereas 4‐month‐olds do not demonstrate such an effect (Experiment 3). Our findings suggest that the mnemonic mechanisms that serve infants' and adults' episodic recognition memory are more similar than previously asserted: they are not fully developed at 4 months of age but that there is contiguity in human episodic memory development from 7 months of age.     

The development of the still-face effect: Mothers do matter

The Face-to-Face Still-Face paradigm (FFSF) has been used to investigate how infants react to stressful events. However, there is little developmental data on the FFSF effect, and whether it connects to a specific relationship (e.g., to a mother versus a stranger). This prospective longitudinal study aims to evaluate developmental changes in infant reaction to the FFSF presented by the mother or a stranger at 2, 4, 6, and 8 months of age (n = 39). Results show that infant negativity was expressed less in relation to a stranger, the identity effect. Results further suggest that from 6 to 8 months of age, stranger induced protest flattens out; whereas mother induced protest decreases. The results are discussed in relation to different theories regarding infant responsiveness.     

The development of joint visual attention: a longitudinal study of gaze following during interactions with mothers and strangers

Two- to 8-month-old infants interacted with their mother or a stranger in a prospective longitudinal gaze following study. Gaze following, as assessed by eye tracking, emerged between 2 and 4 months and stabilized between 6 and 8 months of age. Overall, infants followed the gaze of a stranger more than they followed the gaze of their mothers, demonstrating a stranger preference that emerged between 4 and 6 months of age. These findings do not support the notion that infants acquire gaze following through reinforcement learning. Instead, the findings are discussed with respect to the social cognitive framework, suggesting that young infants are driven by social cognitive motives in their interactions with others.     

Using a virtual reality system to study balance and walking in a virtual outdoor environment: a pilot study.

Falls and fall-related injuries are a major problem for elderly persons. Most falls occur during walking and turning, and the risk of falling increases when attention is diverted to something besides walking. It is often difficult to standardize methods for testing balance and fall tendency in a clinically relevant setting. We describe the development of a system using a virtual environment (VE) to assess how attention demanding and unexpected events influence a person's capacity to control balance and movement. The hardware in the system consists of a head-mounted display (HMD), a magnetic tracker system, and two SGI computers. The software consists of the image generation of the VE and the management and visualization of motion tracking data. In a preliminary pilot study eight subjects (age 23-80) participated. Each subject walked on a normal floor and was visually presented a familiar outdoor environment in the HMD. They were exposed to different unexpected events, such as a virtual snowfall and tilting of the VE. Disturbances of balance and walking patterns such as changes in speed, stride length and balance reactions like slipping were observed. Two subjects experienced symptoms of cyber sickness with a SSQ score above 25 points. Walking with sensors only did not affect walking time, but in VE the subjects generally walked more slowly. Virtual tilting of the environment had an impact on balance performance during walking. This effect was not observed while the test subjects were walking in a virtual snowfall. The model needs further development but may hold a potential for clinical use.     

The social foundation of executive function

In this study, we propose that infant social cognition may ‘bootstrap' the successive development of domain‐general cognition in line with the cultural intelligence hypothesis. Using a longitudinal design, 6‐month‐old infants (N = 118) were assessed on two basic social cognitive tasks targeting the abilities to share attention with others and understanding other peoples' actions. At 10 months, we measured the quality of the child's social learning environment, indexed by parent's abilities to provide scaffolding behaviors during a problem‐solving task. Eight months later, the children were followed up with a cognitive test‐battery, including tasks of inhibitory control and working memory. Our results showed that better infant social action understanding interacted with better parental scaffolding skills in predicting simple inhibitory control in toddlerhood. This suggests that infants' who are better at understanding other's actions are also better equipped to make the most of existing social learning opportunities, which in turn may benefit future non‐social cognitive outcomes.     

Infants use social context to bind actions into a collaborative sequence

Eye tracking was used to show that 18‐month‐old infants are sensitive to social context as a sign that others’ actions are bound together as a collaborative sequence based on a joint goal. Infants observed five identical demonstrations in which Actor 1 moved a block to one location and Actor 2 moved the same block to a new location, creating a sequence of actions that could be considered either individual actions or collaboration. In the test phase, Actor 1 was alone and sitting so that she could reach both locations. The question was whether she would place a new block in the location she had previously (individual goal) or in the location that could be considered the goal of collaboration (joint goal). Importantly, in the Social condition, the actors were socially engaged with each other before and during the demonstration, while in the Non‐Social condition, they were not. Results revealed that infants in the Social condition spontaneously anticipated Actor 1 placing her block in the joint goal location more often than those in the Non‐Social condition. Thus, the social context seems to allow infants to bind actions into a collaborative sequence and anticipate joint rather than individual goals, giving insight into how actions are perceived using top‐down processing early in life.     

Staring us in the face? An embodied theory of innate face preference

Human expertise in face perception grows over development, but even within minutes of birth, infants exhibit an extraordinary sensitivity to face‐like stimuli. The dominant theory accounts for innate face detection by proposing that the neonate brain contains an innate face detection device, dubbed ‘Conspec’. Newborn face preference has been promoted as some of the strongest evidence for innate knowledge, and forms a canonical stage for the modern form of the nature–nurture debate in psychology. Interpretation of newborn face preference results has concentrated on monocular stimulus properties, with little mention or focused investigation of potential binocular involvement. However, the question of whether and how newborns integrate the binocular visual streams bears directly on the generation of observable visual preferences. In this theoretical paper, we employ a synthetic approach utilizing robotic and computational models to draw together the threads of binocular integration and face preference in newborns, and demonstrate cases where the former may explain the latter. We suggest that a system‐level view considering the binocular embodiment of newborn vision may offer a mutually satisfying resolution to some long‐running arguments in the polarizing debate surrounding the existence and causal structure of newborns' ‘innate knowledge’ of faces.