Visual Perceptual Area Definitions - Form Constancy
The ability to recognise forms and objects as the same in various environments (recognise shape, size and characteristics of objects) develops through touch, movement and vision. A child learns that even when objects appear to change size and shape due to changes in its position/orientation that they are still the same. For example a book can be large, small, on its side, turned upside down, in hardback, different colours and shapes, but it remains a book.
Children with Form Constancy difficulties may learn to recognise a number, letter, or word when they see it in a particular script or context, but may be quite unable to recognise the same symbol when it is presented in a different manner, for example, letters or numbers appearing in a different type face, a word that is printed in capital letters, or a number that is represented in an unfamiliar context. A word they know in one form, colour, size, type of writing or in conjunction with certain other words may appear new to them when presented in another form, colour, size, or context. This makes learning to read or to work with symbols very difficult.