On a project where I played both design and development roles, I recall feeling uncomfortable because I was assigned only two days to complete the visual design.

So on dreary days, ask subjects to wear something colourful or stripy to give the image some visual interest and warmth.

After as few as two days, fMRI scans showed bursts of activity in their visual cortex when they performed tasks with their fingers, or even when they listened to tones or words.