EW ratios of the 12.7/11.3 PAH and the 6.2/11.3 PAH for the spectral mapping sample. For each galaxy, values are coloured by the aperture radius used to extract the spectra; a larger aperture will contain more emission from star formation in the galactic disc. The inner purple box shows the CON selection region as defined for the staring mode spectra, and the outer box shows a larger selection region that accounts for aperture correction effects. The grey lines show the mean EW ratios for the star-forming calibration sample. The two bona fide CONs are shown with a red title.