Sometimes brain haemorrhages are caused by injury; they can also occur spontaneously, with weaknesses in brain blood vessels sometimes running in families.

Alternation of the strabismus may occur spontaneously, with or without subjective awareness of the alternation.

The charges are separated from their stable placement in the particles and can occur spontaneously, from pressure or an applied electric field.

Natural mutations seem to occur spontaneously throughout the world; wherever large numbers of plants are being produced, bud-sports will occur.

Reflection may occur spontaneously, but many service-learning programs include either guidelines or specific requirements for structured reflection.