Relativity and Invariance for Perception and Action

This chapter looks at information representation from a different perspective.

We would like perception to be invariant to the position of the head and the inclination of the body

• The 2D pixellated image on the retina is relative to our point of view which is determined by distance and by how the head is angled relative to the objects being looked at.
• One can easily experiment with a camera by turning and tilting it to explore this kind of relativity.

We would like the action specification to be invariant to our physical states such as tiredness, or the weight we might be carrying in a bag

• The precise muscle tension requirements are relative to the weight we carry and our state of exhaustion
• One can easily experiment by going up a long flight of stairs in the morning, after breakfast, or going up the same stairs after a long work day carrying a heavy bag.