In the present study, we recruited at the Technical University Munich (March to August, 2006) 26 healthy male students, aged 21 to 33 years, who were classified with an insecure
attachment pattern using a standardized interview designed and validated to assess attachment patterns in adults by analyzing individual stories to attachment related pictures (Adult Attachment Projective Picture System, AAP) (George and West, 2001
). The AAP drawings depict attachment-related events (e.g. illness, solitude, separation, loss, and abuse). The psychometric properties of the AAP were established in an independent validity study with 144 non-patient subjects. The study (George and West, 2001
) found strong psychometric validity, including high inter-judge reliability, test-retest reliability (after three, six and twelve months), discriminant validity, and convergent construct validity with the Adult Attachment Interview. In recent neuroimaging studies, the feasibility of the AAP in a neurobiological context has successfully been demonstrated (Buchheim et al., 2006
To enable statistical comparisons in the experimental procedure (oxytocin vs. placebo) in the present study, we adapted the attachment task in the following way: The eight pictures (drawings) from the AAP were presented four times in the same order. Each of the 32 picture presentations was accompanied by four prototypical phrases representing one of the four established attachment categories: one secure
and three insecure categories, i. e. insecure-dismissing, insecure-preoccupied
, and unresolved with respect to loss or trauma1
. Subjects were presented these 32 pictures in the attachment task in the two experimental conditions. Secure
individuals demonstrate the ability to draw upon attachment resources (thinking, seeking for help) to remedy distress. Dismissing
individuals avoid or minimize direct expressions of attachment related distress and often take care of situations on their own. Preoccupied
individuals are uncertain if an attachment figure might be available to remedy distress. Individuals, classified as unresolved with respect to loss or trauma
are not able to integrate attachment related fears related to death, attack, abuse or devastation.
To ensure construct validity of the multiple choice version two independent certified judges of the AAP measure classified the alphabetically sorted 128 phrases into one of the four attachment categories. Agreement was achieved in 123 phrases (97%). The overall inter-rater reliability was kappa = .95. This high agreement was achieved in all four attachment categories, secure: kappa =.96; dismissing: kappa = .94. preoccupied: kappa = .96; unresolved: kappa = .94.
The examined subjects were instructed to rank these phrases from the most to the least appropriate for each presentation (). The phrase chosen as most the appropriate (i.e., their first choice) was scored with a value of 3, the second choice with 2, the third choice with 1, and the last choice with 0. Thus, the summed scores for each attachment scale (“secure”, “dismissing”, “preoccupied”, and “unresolved trauma”) ranged from 0 to 96 with a midpoint at 48. Because of the item construction based on the ranking of four statements the sum of these four attachment scales is a 192 (the sum of 0, 1, 2 and 3 = 6 points in each of 32 presentations) constantly by each measurement. The phrases were presented in a randomized balanced sequence in order to minimize simple memory effects across test sessions.
Example of the attachment task (1 of 32 presentations in total).
We used a double-blind, placebo-controlled within-subject design (AB-BA design). The participants were recruited on the basis of a pre-test screening of n=43 healthy male students with an established attachment measure (George and West, 2001
). Eleven subjects with a secure attachment pattern were excluded from the study, because our aim was to examine oxytocin-induced shifts from attachment insecurity towards attachment security. Six subjects refused intranasal application of the substance. The remaining 26 participants were divided into two equally sized, randomly assigned sub-groups to receive the oxytocin or placebo condition first. Only to the collaborating mathematician and the independent administrator masking and blinding the substance were not blind. A single dose of 24 IU oxytocin (Syntocinon spray, Novartis, Basel, Switzerland) or placebo was administered intranasally 50 minutes before the attachment task at both testing sessions (for details of substance administration, see Heinrichs & Domes, 2008
). The placebo contained all inactive ingredients except for the neuropeptide. No undesired side-effects of the substances were observed. Subjects underwent both conditions within a minimum of 2 weeks and a maximum of 3 weeks. In order to control for nonspecific effects of arousal, wakefulness, and mood, we assessed these variables at three time points (before applying the drugs, before filling out the questionnaire, and before the attachment task) by means of a suitable 12-item questionnaire (Steyer et al., 1994
). Drug and session effects were statistically tested by the sign test, a non-parametric paired test, comparing number of decreases and increases of the dependent variable between two experimental conditions. The same subjects were measured under the placebo and oxytocin conditions, with each person serving as his own control. The sign test was chosen for the following reasons. First, the instrument is based having subjects rank order phrases; this is best captured by non-parametrical methods. Second, most of the attachment scales (as well as differences of scales to be compared) did not achieve the normal distribution as measured by the Shapiro-Wilk test. Finally, in formulating the hypothesis of the present study, we expected small to moderate changes that are nonetheless observed by most subjects. The sign test is sensitive to changes of this kind. The study was approved by the local ethics committee at the Technical University of Munich and conducted according the Declaration of Helsinki. All procedures were carried out with the adequate understanding and written consent of the subjects.