We compared maternal speech in interactions of mothers with their firstborn dizygotic twin and singleton infants. Nine twins and nine singletons were video-recorded at home in spontaneous face-to-face interactions with their mothers, from the 2nd to the 6th month. Continuous micro-analysis revealed that there are more quantitative and qualitative…

Infant-directed speech (IDS) is characterized by a range of register-typical characteristics. Many of those can be objectively measured, such as acoustic-prosodic and structural-linguistic modifications. Perceived vocal affect, however, is a socio-emotional IDS characteristic and is subjectively assessed. Vocal affect goes beyond acoustic-prosodic…

Visual attention in complex, dynamic scenes is attracted to locations that contain socially relevant features, such as faces, and to areas that are visually salient. Previous work suggests that there is a "global shift" over development such that observers increasingly attend to faces with age. However, no prior work has tested whether…

Fourteen-month-olds selectively imitated a sub-efficient means (illuminating a lightbox by a head-touch) when this was modeled by linguistic ingroup members in video-demonstrations. A follow-up study with slightly older infants, however, could replicate this effect only in a video-demonstration context. Hence it still remains unclear whether…

Infants are born highly sensitive to the natural patterns found in languages. They use their perceptual sensitivity to acquire detailed information about the structure of languages in their environment. To date, most studies of infant perception and early language acquisition have investigated spoken/auditory languages and hearing infants (e.g.…

This experiment tests the age at which left-to-right spatial associations found in infancy shift to culture-specific spatial biases in later childhood, for both numerical and non-numerical information. Children ages 1-5 years (N = 320) were tested within an eye-tracking paradigm which required passive viewing of a video portraying a spatial…

Measurements of infants' quotidian experiences provide critical information about early development. However, the role of sampling methods in providing these measurements is rarely examined. Here we directly compare language input from hour-long video-recordings and daylong audio-recordings within the same group of 44 infants at 6 and 7 months. We…

This study analyses variation sets in a sample of child-directed speech (CDS) in Turkish in terms of their structure and effect on child speech. The term "variation set" was first introduced to describe the sequences of repetitions, in which the intention behind expressions stays the same throughout the whole conversation while the form…

Behavioral research has shown that 12- but not 9-month-olds imitate an unusual and inefficient action (turning on a lamp with one's forehead) more when the model's hands are free. Rational-imitation accounts suggest that infants evaluate actions based on the rationality principle, that is, they expect people to choose efficient means to achieve a…

Over the last 2 centuries there has been a rapid increase in the proportion of children who grow up in cities. However, relatively little work has explored in detail the physiological and cognitive pathways through which city life may affect early development. To assess this, we observed a cohort of infants growing up in diverse settings across…

Personal narrative is decontextualized talk where individuals recount stories of personal experience about past or future events. As an everyday discursive speech type, narrative potentially invites parents and children to explicitly link together, generalize from, and make inferences about representations--that is, to engage in higher-order…

Personal narrative is decontextualized talk where individuals recount stories of personal experiences about past or future events. As an everyday discursive speech type, narrative potentially invites parents and children to explicitly link together, generalize from, and make inferences about representations--i.e., to engage in higher-order…

It is important to identify Autism Spectrum Disorder (ASD) early to alleviate its developmental impact. This pilot correlational study aimed to identify subtle differences in play and movement in 6-month-old infants that are associated with a later ASD diagnosis through retrospective home video analysis of six children with ASD and nine typically…

This study deals with speech acts addressed to Hadza infants in Tanzania, a group that has traditionally lived off hunting and gathering. Three research questions are addressed: How do Hadza speech acts compare with those found in previous studies in other cultures? Are there differences between child and adult speakers? And do speech acts differ…

Background: Typical scaffolding coding schemes provide overall scores to compare across a sample. As such, insights into the scaffolding process can be obscured: the child's contribution to the learning; the particular skills being taught and learned; and the overall changes in amount of scaffolding over the course of the task. Aims: This study…