Establish whether sensory filtering remains fixed during contrast manipulation

Determine whether the sensory Fourier coefficients \(c_n(\sigma)\) remain unchanged when cue contrast is varied within individual flies, thereby separating contrast-dependent changes in sensory filtering from changes in the neural compass-bump filter.

Background

Behavioral measurements identify only the product of cue-shape, sensory, and neural filters. The within-fly contrast experiment demonstrates that the neural bump changes with contrast, but it does not measure the sensory coefficients in the same manipulation. A simultaneous behavioral spectrum and an independent cue-size or eccentricity manipulation are proposed as ways to separate these latent factors.