Boundary Extension (BE) is a cognitive psychology phenomenon and an error of commission in which people remember more of a scene or boundary than was originally present in the original picture
our prior knowledge/beliefs/experiences dictates our extrapolation of a scene
below we are given 2 images. A subject was given an image to look at for a couple seconds then was told to redraw by memory
/examples-of-boundary-extension-a-typical-drawing-of-an-observer-who-viewed-the-picture.png)