Photoshop Tip: Adjust layer size
Tips & Tutorials, by Mark White
August 7, 2012
Change the way your layers appear in the palette
Change the size of the layer thumbnails by going into the side menu from the palette and selecting Panel Options.
In here are a number of sizes, making it easier to see the contents of a layer.
To see just the outline of the object on any given layer inside its thumbnail, tick the Layer Bounds box.