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There is an alternative route to Artificial Intelligence that diverges from the directions pursued under that banner for the last thirty some years. The traditional approach has emphasized the abstract manipulation of symbols, whose grounding, in physical reality has . rarely been achieved. We explore a research methodology which emphasizes ongoing physical interaction with the environment as the primary source of constraint on the design of intelligent systems. We show how this methodology has recently had significant successes on a par with the most successful classical efforts. We outline plausible future work along these lines which can lead to vastly more ambitious systems.

As a polychromatic X-ray beam passes through matter, low energy photons are preferentially absorbed, and the (logarithmic) attenuation is no longer a linear function of absorber thickness. This leads to various artifacts in reconstructive tomography. If a water bag is used, the nonlinear attenuation in bone causes a distortion of the bone values and a spill-over inside the skull, or 'pseudo-cortex' artifact. If no water bag is used, there is an additional effect due to the varying thickness of soft tissue which causes a depression of interior values, or 'cupping'. Both artifacts can be remedied by additional prefiltering of the beam and by applying a linearization correction to the detector outputs.

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