I noticed this German tourist standing close to me on the subway but unfortunately couldn’t get this shot until she sat across from me. What caught my eye was how amazing she looked in this horizontally-striped dress. She’s a plus size, but this dress didn’t make her look gigantic. One reason: it fit really well. Another reason: the width of the stripes.
According to Imogen Lamport at Insideoutstyleblog,
It’s all to do with the width of the stripes.  Narrow stripes are harder to focus on, but wide stripes are easy to focus on.  When our eye focuses on something it lingers (and slows down, thus making the area appear larger), when the eye can’t focus, the eye moves more quickly over the area thus making the area appear smaller.  The wider the stripe, the more it widens and draws your eye outwards, more narrow stripes draw the eye upwards and are more slimming. Whether horizontal or vertical, wide stripes makes us wider, narrow stripes are more slimming. But if there are only one or two stripes, verticals are more slimming than horizontals.
Also see TracyKM’s theory in her comments to Tuesday’s post. (Nothing after the jump.)
I also really agree with the Imogen Lamport quote. Some of my favourite striped tops have stripes of varying widths, but a wide stripe right at the narrowest part. I find when I wear vertical stripes, because they don't appear straight, I tend to feel curvier (and not always in a good way). Diagonals are good because they're unusual and it takes the brain a moment to figure it out.