Inverted spectrum

C. L. Hardin criticizes the idea that an inverted spectrum would be undetectable on scientific grounds:[3][4] ...there are more perceptually distinguishable shades between red and blue than there are between green and yellow, which would make red-green inversion behaviorally detectable.

From this reductive perspective, sundry qualia inversions are indeed possible, but not without the appropriate rewirings within the entirely physical H–J net that embodies and sustains all of our color experience.

This could be achieved by making small changes to the code governing how colors are displayed, such that what was previously shown as green might now appear as red, without altering the underlying simulated physics.

[6] In his book I Am a Strange Loop, Douglas Hofstadter argues that the inverted spectrum argument entails a form of solipsism in which people can have no idea about what goes on in the minds of others—contrary to the central theme of his work.

He presents several variants to demonstrate the absurdity of this idea: the "inverted political spectrum", in which one person's concept of liberty is identical to another's concept of imprisonment; an inverted "sonic spectrum" in which low musical notes sound like "high" ones and vice versa (which he says is impossible because low sounds can be felt physically as vibrations); and a version in which random, complex qualia such as riding a roller coaster or opening presents are reversed, so that everyone perceives the world in radically different, unknowable ways.