Ainsworth et al. (1978): The Strange Situation.

The Strange Situation Procedure (SSP) was designed as a valid method of measuring attachment in young children. More specifically, it aimed to assess how infants between the ages of 9 and 18 months behaved under conditions of mild stress and novelty. It measured three main factors of attachment theory: anxiety, separation anxiety and secure base.

The SSP is still considered to be the accepted method of assessing the quality of attachments, despite a number of criticisms.

The Procedure.

The SSP comprises eight episodes, most lasting for about three minutes. Episode one (introductions) lasts around thirty seconds. During the procedure, every aspect of the participants’ behaviour is observed and recorded, with special attention given to reunion behaviours, that is, the infants’ responses to their mothers’ return.

Each episode is outlined in the Box 1.

Box 1: SSP Episodes

In the original study, the testing room was an unfamiliar environment of 81 square foot, divided into 16 squares to aid the recording of movements.

Five categories were recorded:

  1. Proximity seeking and contact seeking behaviours.
  2. Contact maintaining behaviours.
  3. Proximity avoiding and interaction avoiding behaviours.
  4. Contact resisting and interaction resisting behaviours.
  5. Search behaviours.


Infants tended to explore the room and the toys more enthusiastically when just the mother was present than when after the stranger entered or when the mother had left the room.

Reunion behaviour showed three specific types of attachment (see box 2), with 70 percent displaying type B (securely attached); 15 percent type A (insecure-avoidant) and 15 percent displaying type C (insecure resistant).

Box 2: Types of attachment


Ainsworth concluded that sensitive responsiveness plays a major role in the quality of attachments. Sensitive mothers are able to correctly interpret the signals emitted by the infant and respond in an appropriate way. Sensitive mothers are more likely to have securely attached babies, whereas insensitive mothers tend to have insecurely attached babies.


The SSP assumes that attachment type is a fixed characteristic. However, behaviours on the day can change in response to, for example, the stress levels of the mother. The behaviour of the mother will then impact how she responds to the child and how the child responds in return.

The procedure lacks what researchers call ecological validity, that is, it representers an artificial environment that is unlikely to replicate itself in the real world. Some researchers have found that the behaviour of the child can alter within different environments, such as the home (e.g. Brofenbrenner, 1979).

The procedures ethics have been called into question because it places very young children is a stressful situation.

Children might act differently in the SSP when they are with a different parent. For example, children might register as insecurely attached with the mother but securely attached with their father (see Main and Weston, 1981).