complex, but quite stereotyped movements carried out slowly with a clear sequence of body parts Head backward, trunk arching, and arms lifting. During pregnancy, they occur infrequently in the human fetes (see figure below). Fetal stretches Appearing for the first the first time 10-15 weeks of gestation, they occur infrequently from 10 to 19 …
Author Archives: Brian Hopkins
Stress (or adrenal) hormones
The hormones, typically corticosteroids, which are involved during the stress response. The hormones of the adrenal cortex respond to internal physiological stress, while those of the adrenal medulla are released in response to stress situations outside the body. See Adrenal cortex, Adrenal gland, Adrenal medulla, Cortisol, Epinephrine (or adrenaline), Hormones, Hypothalamic-pituitary-adrenal (HPA) axis, Methylation, Nerve …
Strange situation test
A test developed and standardised by Mary D. Salter Ainsworth in which a stranger approaches an infant with and without the caregiver being present together with two brief separations, and various aspects of the infant‚was behaviour are measured. Three classes of attachment patterns were originally identified by Ainsworth based on the behavior of 10-24 month-old …
Stopping
A phonological pattern of substituting a stop consonant for another type of sound, especially fricative consonants as in ‘tick’ for ‘sick’. See Cluster reduction, Final consonant reduction, Phonological process, Phonology
Stochasticity
Refers to any process in which there is a random variable or element of probability in its structure, and which as such depends on some parameter that may be discrete or continuous. In a stochastic process consisting of a sequence of discrete events, the outcome of one event has no bearing on the outcome of …
Stimulus orienting
A form of attention in which sensory organs and perceptual systems are aligned to increase responsively to environmental events. This type of attention is present at birth and is fully developed very early in infancy. See Attention, Overt attention
Stimulus generalization
The tendency for a stimulus that has been conditioned to elicit similar responses even after the response has been conditioned. The classical example is the Little Albert experiment carried out by John B. Watson and Rosalie Rayner in 1920: following a baseline period in which he was allowed to play with a white rat, the …
Stimulus-response compatibility
A situation in which critical features of the stimulus and the response are the same. For example, this arises when subjects are asked to press the ‚aaleft‚aa key (the response) when they see a dot appear on the left side of the visual field (the stimulus). Humans respond more quickly and with fewer errors in …
Stimulus enhancement
An object may become the focus of attention by virtue of the fact that someone else uses it. Such attention may lead the observer to increased manipulation of it, which in turn leads to the chance production of behaviours. Studies of imitation often attempt to distinguish stimulus enhancement from imitation . See Attention, Imitation
Stimulus-driven development
Also referred to as sensory-driven development, the termrefers to neural development of the brain on the basis of stimulation it isexposed to. As a result ofstimulus-driven development, infants, for example, develop neural memory tracesfor their native language phonemes. Incontrast, the lack of specific stimulation retards the cortical regions thatwould otherwise process such stimuli, such as …