This book summarised the results of observations made during the Baltimore studies. Although Ainsworth viewed attachment as continuous, for convenience she defined three styles of mother-infant relationship: 

Avoidant (A)
Infant not interested in mother but attention displaced to toys. This can appear to be confident exploration but 'displacement exploratory behaviour is devoid of the true interest that is inherent in non-anxious exploration' (pp. 319-320). Infant displays detachment behaviour on separation and avoidance of the caregiver. Mother rejecting, rigid and hostile. Tends to be insensitive to infant's signals and rebuff or deflect when the infant attemtpts to gain proximity - especially bodily contact.

Secure (B)
Infant engages in active exploration. Upset by separation. Positive response to caregiver. Will be quite wary of strangers during infancy. Mother consistently sensitive and responsive to infant's signals. Available and warm.

Anxious/Ambivalent (C)
Infant preoccupied with mother's availability. Protest behaviours and distress on separation. Anger-ambivalence to caregiver. Mother inconsistent in response to infant's signals. Insensitive and frequently  intrusive.