Systematic variance that characterises the time interval under study . See Variance (between), Variance (within)
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Time-lag design
The study of one age group across developmental or historical time . See Developmental (or ontogenetic) time. Longitudinal studies
Time-adjacent observations
Repeated measures directly next to each other in the temporal sequence of observations. See Time-series
Timbre
Tonal quality of sounds that distinguishes one vowel from another. See Cochlea, Pitch
Tiers
In Fischer‚aas neo-Piagetian skill theory, the broadest set of distinctions in the degree of hierarchical integration of an action and thought. Accordingly, there are four tiers of development Reflexes, sensorimotor actions, representations and abstractions. The concept of tier and the related concept of levels stands parallel but in contrast to the Piagetian notion of stage. …
Thrombophilic disorders
A disorder of the hemopoietic system responsible for the formation of blood cells in which there is a tendency to the occurrence of thrombosis (blood clots). When these occur in the brain, they can cause hemiplegia . See Cerebral palsies, Spastic hemiplegia
Thymine
Also known as 5-methyl-2, 6-dioxytetrahydropyridime, it is one of four molecules that form the base pairs of DNA, but not RNA. In DNA, it is always paired with the purine adenine. See Adenine, DNA (deoxyribonucleic acid), Nucleotide, Pyrimidines, Purines, RNA
Thermodynamics
See Classical thermodynamics
Theory of the germ plasm
The theory of Augustus Weismann (1834-1914) that the cells destined to become reproductive cells are segregated very early in development and are thus untouched by influences from the environment or from anywhere else in the body. They are transmitted unchanged from generation to generation (and thus are ‘immortal’) and have no role in development, but …
Theory of sexual selection
Originally proposed by Darwin (in his book The descent of man, 1871), it is a form of selection that is typically contrasted with natural selection. According to the theory, sexual selection results from mating preferences (most often by females) in favor of those members of the opposite sex expressing certain genetically determined characters (e.g., the …