Limitation validity of monotropy is challenged. Schaffer and Emerson 1964 found most babies did attach to one person in particular at first, but then later on m lost of them formed multiple attachments. Even though the fist attachment does appear to be a particularly strong influence on later behaviour it may simply mean it is stronger, but not different in quality from the child's other attachments. Other attachments to other family members provide all of the same key qualities. Means that Bowlby may be incorrect that there is a unique quality & importance of the child's first attachment.