Human intelligence differences: towards a combined experimental-differential approach

Despite the fact that much is known about the taxonomy and predictive valid ity of human intelligence differences, there has been relatively little pro gress in understanding their cognitive bases. However, some recent firm fin dings mark the beginnings of a cognitive reductionism in human intelligence . Progress towards discovering 'cognitive components' that, firstly, show i ndividual differences and, secondly, relate to psychometric intelligence di fferences is described here at different nominal levels of analysis: 'psych ometric: 'cognitive-experimental' and 'psychophysical: The field of intelli gence differences remains a fertile yet seriously under-developed demesne i n which cognitive scientists should collaborate with differential psycholog ists.