A pattern of behavior in some birds characterized by lying on the side and making a small depression in the surface while bill raking, head rubbing, scratching and wing shaking, and scratching on the surface (see figure below). The birds throw particles of surface material over their bodies and the surrounding area during dust bathing, …
Author Archives: Brian Hopkins
Dynamic field theory
A theoretical framework in which ideas from the dynamical systems approach are extended to address how information is processed. The concept of activation is used similarly as in connectionism, but strong interactions within an activation dynamics lead to attractors and instabilities. The application of a dynamic field theory in psychology is not new. In the …
Ductus Botalli (or ductus arteriosus)
Part of the fetal circulation. It directly connects the left pulmonary artery to the aorta, thereby bypassing circulation of the non-ventilated lungs and resulting in re-circulation of arterial blood through the lungs (see figure below). If it persists after delivery in live births of 2500 grams or more, then surgery may be required to close …
Dualism
A theory of ontology that there are only two real substances in the universe, one being material and the other being mental. Thus, the mind and body (or brain) exist independently of each other and have entirely different essences or natures. Historically, it is exemplified by the following distinctions: Pre-Socratic appearance-reality, Plato’s forms-world, Descartes’s mind-matter, Hume’s …
Dubowitz scale
44 Scores derived from summing those obtained for neuromotor and physical maturity on the Dubowitz/Ballard examination that provide estimates of gestational age. See Gestational age, Preterm infant
Dual x-ray energy absorptiometry (DEXA)
A method for estimating body composition, specifically bone mineral density (strength), fat-free soft tissues and fat. The method requires a low radiation exposure in the form of two photon beams, one of low energy and the other of high energy. In fact, the amount of radiation is less than 1/10th the dose of a standard …
Down’s syndrome
A chromosomal abnormality characterized in most cases by the presence of extra genes associated with the 21st chromosome, which in its normal state contains just 30 or so genes. Being the most common congenital disorder in humans, its estimated incidence ranges from about one per 700 to one per 1000 live births. The risk of …
Downward causation (or macrocausation)
A concept introduced by Donald T. Campbell (1916-1996) in 1974 in order to combat radical reductionism and the excesses of bottom-up explanations as provided by genetic determinism. It is evident when a higher level of a system determines the behavior of lower levels of organization. Under this influence, all processes at lower levels are constrained …
Doublets (or geminates)
Repeated letters, as in ‘hopping’ and ‘hoop’. In some scripts, doublets have an important and consistent function, in others none at all. In Finnish, for example, doublets signify long phonemes (both vowels and consonants), whereas in French doublet consonants, though plentiful, have no relation to phonology at all. See Phoneme, Phonology
Double dissociation
95% There are many who have questioned the logic of double dissociations as a means of identifying particular brain areas as the substrates for particular functions. One criticism is that this approach assumes that a specific region of the brain has a unitary function when there is considerable evidence for one anatomically or histologically identifiable …