This is an interesting exercise, seeing how the context of a colour affects the way it is perceived. The exercise asked for six squares of different coloured paper with smaller squares of one colour in the centre. Then see how they look different from each other. I find looking at the image here is different to looking at the actual papers in my workbook. The blue square on the yellow looks much brighter in both. On the original sheet I find the pink square pops a lot more too. I find you can’t look too long at the squares or your brain takes over too much and starts to fight with your eyes.
Looking at the original sheet for this image the yellow against the blue looks partiularly greenish. Also the yellow against the gold is very warm and the yellow against the orange looks a bit grey/green.
Here the blue against the gold background seems very bright compared to the blue against the mauve square. The blue against the orange square seems to take some of the colour away and make the orange appear slightly gray.