Anti-trait movement (1968). The anti-trait movement was launched by Mischel in 1968 in his book Personality and Assessment. According to Mischel, trait measures of personality showed little consistency across either settings or over time, and were of little predictive value, i.e. the person interacted with the situation (or environment) in which they found themselves. This is often referred to as the person-situation debate. To a degree, Mischel's thesis is similar in complaint to those that dogged attitude researchers at the same time - if traits or attitudes cannot predict behaviour, then what use are they? Defendants of trait theories argued that the studies chosen by Mischel to illustrate his point were particularly poor, and that better methodology would lead to better prediction of behaviour across time or situations. As with many debates in psychology, a great deal of effort was spent in trying to establish how much of people's behaviour can be predicted from knowing their traits and how much depends on the situation (i.e. person x situation interactions). Thus, if a personality measure of punctuality can predict 30% of the variance in a person's punctuality on a specific occasion, it inevitably follows that 70% of the variance is due to the situation. However, there are many difficulties in analysing what situation is and, in practice, it has generally been considered to be everything that is not the person (i.e. not a trait). As a result, there has been little advance in understanding what aspects of the situation or environment influence behaviour.