Lakoff and Nuñez (2000) use related conceptual blending ideas, but also employ a series of metaphors for number and number operation to build their description of the conceptual development of complex numbers. The metaphor for negative numbers was particularly interesting to us. They write, “…negative numbers are conceptualized by the cognitive, spatial rotation operation via the metaphor Multiplication by –1 is rotation.” By blending this multiplication-as-rotation metaphor with the Cartesian plane, the rotation-plane blend is realized.
Then the complex plane is the rotation-plane blend combined with the notion that i = –1 in the sense that if rotation by 180 degrees is multiplication by -1, then rotation by 90 degrees must be
–1 which must be the (0,1) point on the plane.