When one-year-old Timmy enters an unfamiliar laboratory playroom with his mother, he stays near her for a while. But soon, he ventures out to play with some interesting toys, looking back at his mother every minute or two. Timmy gives his mother a few toys every few minutes. Later, the mother leaves the room for a minute; Timmy cries and becomes distressed, but quickly calms down after his mother returns.
According to Mary Ainsworth, which type of attachment pattern does Timmy demonstrate?