We address the effects of bar-driven secular evolution in discs by comparing their properties in a sample of nearly 700 unbarred and barred ( 42 \pm 3 per cent of the population ) massive disc galaxies ( M _ { \star } \geq 10 ^ { 10 } M _ { \odot } ) .
We make use of accurate structural parameters derived from i -band bulge/disc/bar decompositions to show that , as a population , barred discs tend to have fainter central surface brightness ( \Delta \mu _ { 0 } \approx 0.25 mag ) , and disc scale lengths that are \approx 15 per cent larger than those of unbarred galaxies of the same stellar mass .
The corresponding distributions of \mu _ { 0 } and h are statistically inconsistent at the 5.2 \sigma and 3.8 \sigma levels , respectively .
Bars rarely occur in high-surface brightness discs , with less than 5 per cent of the barred population having \mu _ { 0 } < 19.5 mag arcsec ^ { -2 } – compared to 20 per cent for unbarred galaxies .
They tend to reside in moderately blue discs , with a bar fraction that peaks at ( g - i ) _ { disc } \approx 0.95 mag and mildly declines for both bluer and redder colours .
These results demonstrate noticeable structural differences between the discs of barred and unbarred galaxies , which we argue are the result of bar-driven evolution – in qualitative agreement with longstanding theoretical expectations .