How to measure embodied intelligence?

Embodied intelligence (EI) summarizes design approaches that give robots efficient physical interaction with their surrounding environment. EI has, to date, found an extensive descriptive treatment yet lacks universal metrics. Could we quantify EI? What would be the EI analog to intelligence quotient (IQ) in humans? We first suggest an intelligent unit (intel-unit) as the smallest entity that displays program execution beyond simple stimuli-responsiveness. The emergence of EI by situatedness of encoded physical agents in an environment is explored in three case studies. First, an awn of a wild oat – a non-living structure in nature that satisfies all robot's descriptions – is analyzed in terms of material-level intelligence. Next, a jocular quantitative scale found with a popular gadget – the 'fortune teller fish' – is given treatment in the EI context. Finally, the learned and summarized EI principles are tested on a well-known object with perceived intelligence yet lacking a consensual robotic description – a knitted woollen sweater. We confirm the necessity of treating environment interactions in expressions and definitions of EI, as situatedness is central in defining functionality. Universal metrics would identify non-intuitive representations of EI and lead from empirical to model-based design of unconventional robots. Robots that engage situatedness provide a physical interface to artificial intelligence, similar to our bodies communicating with our brains.