Brand is a proponent of IQ testing and the general intelligence factor and was "a major influence in the spread of influence of inspection time as a theoretically interesting correlate of psychometric intelligence," according to Ian Deary and Pauline Smith in the International Handbook of Intelligence, edited by Robert Sternberg.
Moreover, Demetriou's theory integrated models from cognitive, psychometric, and developmental psychology into an overarching model that describes the architecture of the human mind, its development, and individual differences in regard to both architecture and development.