In biology, the structural and functional unit of all living organisms, which exists as an independent unit of life in bacteria and protozoans, and first described by Robert Hooke (1635-1703) in 1665 with the aid of a light microscope. In other living organisms, they form colonies or tissues. Each cell contains protoplasm differentiated into cytoplasm …
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Causality (in philosophy)
Covers three distinct meanings. To begin with, there is causation (the causal relationship between two things when the first is a necessary and/or sufficient condition the occurrence of the second), the causality principle (a statement of the law of causation in the form ‘The same cause always or invariably produces the same effect’), and causal …
Causality (as a psychological phenomenon)
Perception of cause-effect relationships among objects. The roots of this interpretation of causality lie with David Hume (1711-1776) who argued that causality is not a logical relationship waiting to be discovered, but rather is based on inferences derived from experiencing a succession of events. With this contention, he shifted the study of causality from logic …
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Causal pathway
The sequence of causes leading to the outcome of interest. In epidemiology and the design of clinical trials, the identification of causal pathways leading to pathology is a major objective. In studying development, normal or pathological, causal pathways can be more readily identified from retrospective studies than from longitudinal data gathered prospectively. Structural equation modelling …
Causal determinism (or causalism)
The doctrinal assertion of the causality principle. In general terms, it advocates the idea that every event is necessitated by antecedent events and conditions, together with the laws of nature. Pursued thoroughly enough, it has been held, then it will explain all phenomena and thus give rise to a Theory of Everything. See Cause (or …
Category learning
The ability to group objects together that are perceptually dissimilar (e.g., different cats), and treat them as members of a single category. The ability to form categories has been shown to exist even in 3-month-old infants. However, the category structures of infants differ from those of adults. It is a crucial type of learning as …
Caudal
From the Latin word for a ‘tail’, it means at the back or end of the longitudinal axis of the body or organ, and in the brain toward the brain stem. Used as a directional term in anatomy and physiology. See Dorsal, Neurulation, Rostral, Ventral
Catecholamines
A group of hormones that act as neurotransmitters, which are mainly manufactured by the chromatin cells (the secretory organelles) of the medulla of the adrenal glands and from the postganglionic fibbers of the sympathetic nervous system. The most abundant catecholamines are three closely related chemical messengers:epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine, all of which are …
Categorical perception
A perceptual phenomenon by whichvarious instances of stimuli equally distant from each other in their physicalproperties are mapped to different perceptual categories (i.e., /b/ and /p/). Thus, it means that a change insome variable along a continuum not perceived as gradual but as an instance of a discrete categorie. Some stimuli are perceived as belonging to …
Catching
Grasping a moving object with one or two hands. See Prehension