The shapes are all able to be written in a way that visits points in the corners of the square in the same order (UL, LL, UR, LR). So 0111 and 1110 can be writ

The shapes are all able to be written in a way that visits points in the corners of the square in the same order (UL, LL, UR, LR). So 0111 and 1110 can be written with the skewed V shape because the 1's are in sequence, while 1011 and 1101 are written with rotated L shapes because they skip one of the middle bits. (Compare also 1111, a backwards N shape).