The ability to postpone or inhibit a desired response or behaviour. The importance of delayed gratification for understanding individual differences in child development came to prominence as a consequence of the famous Stanford marshmallow experiment carried in 1960s by Walter Mischel in a preschool on the university campus. He told four-year children that they could …
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Delivery position (or presentation)
Refers to the part of the fetus’s body that is in advance during birth. For vertex presentation, which is the normal cephalic presentation, the head is delivered first. In most cases, the infant’s back is to the left side of the mother’s pelvis (left occiput anterior), in other cases to her right (right occiput anterior) …
Delay(ed) conditioning
A classical conditioning procedure in which the conditional stimulus begins before and overlaps with the onset of the unconditional stimulus. The two stimuli then terminate together. See Classical conditioning, Learning, Operant (or instrumental) conditioning
Dehoaxing
A form of debriefing, it is a procedure designed to make good the consequences of any false information (e.g., via deception) that was provided to a participant earlier in the research. See Benefience, Debriefing, Desensitizing
Dehydroepiandrosterone (DHEA)
An endogenous steroid hormone produced from cholesterol and secreted by the adrenal glands in the adrenal cortex. After being secreted by the adrenal glands, it circulates in the bloodstream as DHEA-sulfate (DHEAS), and is converted as needed into other hormones such as testosterone. Its conversion into testosterone may account for the fact that low blood …
Degrees of freedom (or Bernstein’s) problem
In engineering, the degrees of freedom of a system are the minimum of independent co-coordinates that are needed to specify uniquely the state of configuration of a system, without violating how its parts are interrelated. The arm has seven degrees of freedom: three at the shoulder (flexion-extension, abduction-adduction, rotation about its axis), one at the elbow …
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Deep and surface structure (linguistics)
Surface structure is the actual spoken sentence comprising phonemes, syllables, words, phrases, sentences, and deep structure the underlying meaning of the sentence. A single idea constituting a deep structure can be expressed in a number of different surface structures (and conversely similar surface structures can have completely different deep structures). For example: * John hits …
Deep cerebellar nuclei
Four nuclei located deep in the cerebellar hemispheres, namely, the dentate nucleus (the largest), the globose emboliform nucleus and fastigial nucleus (which together form the nucleus interpositus), and the globose nucleus (see figure below). All are relay stations for the Purkinje cells from different cerebellar regions. The dentate nucleus receives inputs from the Purkinje cells …
Deduction
A method of reasoning or logical inference going from the general to the particular (or from cause to effect). In another respect, and according to Karl R. Popper (1902-1994), it involves stating a theory first and then trying to find facts to reject it. Darwin and Piaget are usually offered as prime examples of using …
Deductive-nomological (D-N) model
Also known as the covering law model of scientific explanation, it means in effect ‘deduction from laws’. According to the model, put forward by Carl Gustav Hempel (1905-1997) and Paul Oppenheim in 1948, scientific explanations deduce a statement describing a phenomenon to be explained (the explanandum) from a statement (the explanans) specifying a law, or …