Both specific functions and general ability can be useful: but it depends what type of research question you ask.
Phillips
Louise
L
Psychology Department, Aberdeen University, Aberdeen, Scotland. louise.phillips@abdn.ac.uk
D000375:Aging / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests; D011582:Psychological Theory; D011594:Psychometrics / Q000379:methods; D012107:Research Design