A branch of psychology that is concerned with intelligence and thought processes. It tries to understand the complexity of the relationship between an individual’s thought and action.

A generation of people (or animals) all born during the same period of time.

Those aspects of a person’s biography that are common to the particular cohort or group to which they belong.

An enzyme that breaks down the protein collagen.

A substance made up of two or more types of atom.

This claims that disease and decay have largely been eliminated until the very last few years of the lifespan.

A gradient that exists when there is a difference in concentration of a particular substance, which results in the net movement of the substance from the region of high concentration to the one of lower concentration.

The extent to which halves of a twin pair correlate in some quality, e.g. height or IQ.

A stimulus that owes its behavioural capacity to its association with an unconditional stimulus. For example, a CS (bell) might evoke salivation as a result of its earlier pairing with food.

The reflex that links a conditional stimulus and a conditional response, e.g. the neurons that link the sound of a bell (after conditioning) with the production of saliva.