Behavourists view that attachment in a learnt process and that it isn't innate (the desire to attach instantly)
Attachment is learnt through two types of conditioning.
One called Classical and the other known as Operant.
Classical is when the baby associates the primary care give with pleasure. The primary care giver provides the baby with food which gives the baby pleasure when hungry. The baby then on associates the mother with food and pleasure.
Operant is when you learn through rewards and consequence. If the baby eats all their food then the primary care giver might say "clever boy/girl." Whereas if the baby chucks all their food on the floor the primary care giver might say "thats naughty, dont do that"
A strength of the learning theory is that we DO learn through association and reinforcement.
A weakness of the learning theory is that FOOD isn't the main reinforcer. Harlows study on monkeys found that the monkey attached to the wire 'mother' covered in blankets rather than the wire mother with food showing that the main reinforcer of attachment could be comfort.