These early papers mainly focused on the timing of innovations and considered R&D investment and human skills as the main drivers of innovation, but do not view the technological innovation process as absorptive capacity. Cohen and Levinthal (1990) introduced the concept of absorptive capacity, which is the ability to recognise the value of new, external information, to assimilate it, and to apply it. These authors consider two faces of technological innovation: creation and absorption. In their model, some level of absorptive capacity is necessary to create, and the cost of adoption increases as absorptive capacity falls. Hence, technological innovation is considered to reduce the cost of adoption. Zahra and George (2002) distinguished not only two subsets (potential and realised absorptive capacity), but also four dimensions of absorptive capacity: acquisition, assimilation, transformation and exploitation capabilities. Knowledge acquisition and assimilation capabilities compose the potential absorptive capacity, whereas knowledge transformation and exploitation compose in the realised absorptive capacity. Their model highlights external sources of knowledge and experience as key antecedents of absorptive capacity. Along these lines, the learning process will lead to an ambiguous effect of technological innovation on exports that will affect the capacity of the country (sector) to acquire, assimilate, transform and exploit new external information. On the one hand, the more "experience" about techniques gained by using them, the greater the rate at which these techniques become more productive. On the other hand, international transmission of new techniques carries a cost because learning-by-doing must occur locally in order to reduce local costs. Hence, the learning process must be taken into account to analyse the relationship between technological innovation and exports at a national level. This relationship could significantly differ depending on the specific component of technological innovation considered. With respect to the TAI index, a higher potential absorptive capacity could be related to a higher level of technology creation and diffusion of old innovations, whereas a higher realised potential absorptive capacity could be related to a higher level of diffusion of recent innovations and human skills.