One theory is that there is under-stimulation of brain areas responsible for attention.

Many situations in working life, however, are characterized by either over- or under-stimulation, or worse, both.

Neglect can also be a matter of global under-stimulation that compromises the growth of the cortex.

Further secondary effects are under-stimulation, frustration, behavioural problems, inappropriate behaviour and dependency, as well as isolation.

In summary, extreme unity leads to under-stimulation, extreme complexity leads to over-stimulation.

He now appreciates that the combination of a physically abused child's abnormally low weight, under-stimulation and the general lack of competent parenting are the indicia of predictive child abuse.

In infants and the cognitively impaired, the disease has normally been attributed to over-stimulation and under-stimulation from parents and caregivers, causing the individual to seek self-gratification and self-stimulus due to the lack or abundance of external stimuli.