The seven primary mental abilities in Thrustone's model were verbal comprehension, word fluency, number facility, spatial visualization, associative memory, perpetual speed,and reasoning.
The Abbasids established the new position of vizier to delegate central authority, and delegated even greater authority to local emirs. The Abbasid dynasty ruled as caliphs from their capital in Baghdad, in modern Iraq, after taking over authority of the Muslim empire from the Umayyads in 750 CE.
