A measure of a body’s inertia (i.e., its resistance to acceleration) and termed inertial mass. According to Newton’s law of universal gravitation, mass can also be defined in terms of the gravitational force it produces, and which is called gravitational mass. The latter is used to measure weight and in defining the kilogram, the SI …
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Mastery
A person’s subjective view of the extent to which he or she can influence events and conditions, rather than believing that fate or external forces control outcomes. Higher mastery is considered a psychological resource that may reduce social stress when the person faces undesirable events or conditions. See Competence (psychological), Learned helplessness, Phonemic mastery, Self, …
Masked threshold
The ability of a listener to detect an auditory signal (e.g., a pure tone) amongst noise. It is typically expressed as decibles (db). A well-known example is the cocktail party effect. See Sensitivity threshold, Temporal resolution, Temporal contiguity window
Mappings
In Kurt Fischer’s neo-Piagetian skill theory, a concept borrowed from mathematics to describe a level of functioning in which an individual is able to control the relationship between two units of behavior. For example, using representational mappings, a 4-year-old child can hold in mind the relationship between two representations. In so doing, she maps one representation …
Marfan syndrome
A disorder inherited as an autosomal dominant trait and marked by defective formation of elastic fibers that affects the skeleton, large arteries, suspensory ligaments of the lens of the eye, tendons, and joint capsules. If afflicts 1/5000 to 1/10,000 people, making it more common, for example, than cystic fibrosis. Sufferers have abnormally long slender extremities, …
Major depressive disorder
At least five of the following symptoms must be present during the same two-week period (according to ICD-10, less than a two-week period if symptoms are severe and of rapid onset): 1. depressed or irritable mood, 2. anhedonia, 3. significant decrease or increase in weight or appetite or failure to make expected weight gain, 4. insomnia …
Magnetic resonance imaging (MRI)
Based on magnetic fields and pulsed radio frequencies without ionising radiation, it is a class of techniques that use the static or changing properties of polar molecules in the brain, such as haemoglobin, to visualise its structures, or activity in structures. Also used to estimate body composition, specifically images of fat, muscle and bone tissues. …
Magnetoencephalography (MEG)
A technique of brain imaging that measures the magnetic fields created by the induction of electrical activity of nerve cells. Unlike conventional EEG that detects radially oriented electrical activity, which is perpendicular to the cortical surface, MEG measures activity tangentially, with less scalp-induced distortion than EEG. See Brain (neuro-) imaging, Dewar, Diffusion tensor magnetic resonance …
Macroevolution (or horizontal evolution) and microevolution (or vertical evolution)
This distinction is essentially one about the tempo of biological evolution. Microevolution manifests itself as continuous, small changes in gene frequencies within a population (phyletic gradualism). In contrast, macroevolution appears as sudden, gross changes in morphology and function that mark the emergence of a new species. It refers to two issues: the evolutionary origin and extinction …
Méthode clinique
Namegiven to the combination of naturalistic observation, psychometricquestioning, and psychiatric clinical examination devised by Jean Piaget (see Mayer, 2006). . See Cognitive development, Neo-Piagetian theories of cognitive development, Qualitative research Mayer, S. J. (2005). The earlyevolution of Jean Piaget’s clinical method. History of Psychology, 8,362.