A neologism devised by Conrad H. Waddington (1903-1975) to signal his attempt at integrating genetics, embryology and evolutionary biology into a unified developmental science based on dynamical principles. According to diachronic biology, evolutionary change is engendered by heritable alterations in development, with stabilising selection within the embryo being followed by normative selection on the adult. …
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Diachronic emergence
The emergence of new structures in the language through pressures from social group differentiation and stylistic variation over historical time. Diachronic linguistics is the study of language change over such time. ‘Diachronic’ is from the Greek dia meaning ”through’ and chronos meaning ‘time’, and is opposed with ‘synchronic’ standing for ‘at one point in time’. …
Dewar
Insulating storage vessel or flask made from glass or metal that uses a vacuum to reduce heat exchange of storedliquid with the surrounding. For magneto encephalographic recordings, the SQUIDsensors are installed in thedewar containing liquified helium to ensuresuperconductivity. Invented by James Dewar (1842-1923) in 1892. See Magnetoencephalography (MEG), SQUID
Developmental velocity
Units of change in a developmental variable during a specified time interval. It is obtained by subtracting two age-related values from each other. For example, if a group of infants had a mean score of say 10 seconds for looking at a display followed by 15 seconds at the next age, then the measure of …
Deviance statistic
Used in multilevel modelling, it is a statistic that follows the chi-square distribution, which is used to compare the fit of two models after one or more parameters have been added or deleted. The lower deviance, the better the fit. Many models can fit the data, and so the usual tactic is to obtain deviance …
Developmental trajectories
Patterns of developmental change that are either hypothesized or actual, and in the latter case that may be used to identify sub-groups of individuals with similar trajectories. Individuals may differ in the starting point for the emergence of a particular function, the relative amount and timing of acceleration and velocity, overall shape of the curve, …
Developmental risks
Risks that are associated with some probability of a deviant developmental course, or trajectory; risks (e.g., very preterm birth) with outcomes (e.g., cerebral palsy) later in a child’s development. More fully, developmental risk can be defined as an event (e.g., chromosomal disorder), circumstance (e.g., severe intrauterine growth restriction) or property (e.g., neurological disturbance) about which …
Developmental screening
Refers to some form of assessment carried out to check that the child’s development is proceeding as expected. More specifically, the purpose of developmental screening is to identify or detect children who are in need of further evaluation and diagnosis. Thus, such an instrument cannot serve to provide a diagnosis, and at best is a …
Developmental readiness
As a general concept, ‘readiness’ refers to a state of preparedness through that an organism is set to act or respond (e.g., sexual readiness) or to benefit from experience. Applied to development, it can be considered to be the age-related capacity of the individual to function effectively in specific situations. In practice, developmental readiness proves …
Developmental research
The systematic study of constancy and change across the life-span (i.e., in inter-individual differences in intra-individual change). Strictly speaking, with a major commitment to the study of intra-individual change, it is based on a longitudinal, not cross-sectional, designs, or some combination of the two as a means of accounting for learning effects derived from repeated …