For more than a century, the standard view in the field of human intelligence has been that there is a “general intelligence” that permeates all human cognitive activity. This general cognitive ability is supposed to explain the positive manifold, the finding that intelligence tests with different content all correlate. However, this interpretation does not sit well with findings from cognitive psychology and neuroscience that point to the domain-specific modular fractionation of cognition.

In my research talk I will present an alternative interpretation - process overlap theory - a new theoretical framework for the study of individual differences in cognitive ability (Conway & Kovacs, 2013; 2015; Kovacs & Conway, 2016; 2019). The theory assumes that most forms of complex cognition, and IQ test items, require a number of domain-general as well as domain-specific processes. Domain-general processes involved in executive attention are central to test performance. That is, they are activated by a large number of test items, alongside with domain-specific processes tapped by specific types of tests only. Such an overlap of executive processes explains the positive manifold as well as the hierarchical structure of cognitive abilities and rejects the notion of a general mental ability.

As a consequence of the theory, IQ is redefined as an emergent formative construct rather than a reflective latent trait. This implies that IQ should be interpreted as an index of specific cognitive abilities rather than the reflection of an underlying general cognitive ability. The consequences of this new approach will be discussed, including a focus on specific abilities rather than on global measures of cognitive performance.