Dissipative system

In irreversible thermodynamics, it is a non-linear system capable of assimilating large reserves of energy from the environment and converting them into increasing structural complexity, thus maintaining its integrity while it is far-from-equilibrium.  Existing in a far-from-equilibrium state, such a thermodynamically open system shows spontaneous internal fluctuations that can be amplified to the point that …

Display rules

The understanding of when, where and how to control emotional expressions according to cultural expectations (see figure below).  Consequently, there is a large cultural (and individual) variation in such rules (e.g., shaking the head from side-to-side to indicate ‘no’ is common, but in Greece it can be done by titling the head backward and lowering …

Disorder

A disturbance of function, structure, or both, resulting from a genetic or embryonic failure in development or from exogenous factors such as poison, trauma, or disease.  See Developmental disorder, Disability, Impairment, Learning disability, Nosology, Teratogen

Displacement activities

Actions studied by ethologists that appear out of context or irrelevant to the situation, such as scratching movements or self-grooming behavior during anxiety, conflict, embarrassment, frustration or stress.  Sometimes interpreted as a defence mechanism, involving motivational disinhibition, and in non-humans as an instinct.  In contrast to displacement activity, there is redirected activity: actions directed away from …

Discrimination

A difference in responding resulting from differential consequences of responding in the presence of different stimuli.  Given this definition, it can also be regarded as a class of experimental procedures, which together are referred to as discrimination training procedures (e.g., as in classical or operant conditioning).  In such procedures, the response is reinforced in the …

Discriminant validity

An aspect of construct validity, in which measures of constructs that theoretically should not be related to each other are shown, in fact, not to be related to each other (i.e., you should be able to discriminate between dissimilar constructs).  Together with convergent validity it provides evidence of construct validity.  Thus, neither alone is sufficient …

Discipline

Its meaning and allocation to subjects has changed considerably over historical time.  Whatever the meanings offered, they have never included the tools used (e.g., developmental biology studies the development of multicellular organisms using whatever tools are available).  By the 18th century, and following Gottfried W. Leibniz (1646-1716) who was reputed to be the last person …

Disability

According to the International Classification of Impairments, Disabilities and Handicaps (World Health Organization, 2001), any restriction or lack of ability to perform an activity in a manner or within the range considered normal for a human being.  As the term reflects the consequences of impairment with regard to functional performance and activity by the individual, …