Introduction: the place of states in trait theory

Traits refer to stabilities of behaviour and beliefs about our enduring dispositions. However, we must also take into account the variation over time of the person's ‘state of mind’ or ‘transient internal conditions’ (Eysenck and Eysenck, 1980). Since antiquity, philosophers such as Aristotle and Cicero distinguished temporary emotional states from stable dispositions. Someone whose personality is characterised by trait anxiety is not usually anxious the whole time. The high trait anxious person may experience feelings of anxiety more often and more intensely than the low trait anxious person, but, even so, periods of feeling anxious alternative with periods of more relaxed states of mind (Spielberger, 1966). Similarly, even extraverts may occasionally wish for solitude, and introverts may sometimes be in a party mood. Short-lasting, unstable general characteristics of the person, such as a temporary feeling of anxiety or sociability, are known as states. In principle, states may refer to any reliably measurable characteristic, but, typically, state variables refer to conscious, verbally reportable qualities such as moods.

Interest in dimensions of mood goes back to Wilhelm Wundt (1897), but, in the behaviourist epoch, the field languished until the 1950s and 1960s. Nowlis (1965) developed a pioneering adjective checklist, requiring the person to rate how well each adjective corresponded to their present mood. Although Nowlis hypothesised twelve dimensions of mood, subsequent work has reduced dimensionality to as few as two or three fundamental constructs.