Measuring aggression regulation: Development of the Method of Stamp Strike Shout: Clinical sample

There is an increased interest in medical research on anger coping strategies
(Trnka & Stuchlíková , 2011). Turning one*s anger inwards instead of expressing
it, is found to have severe consequences for one*s health and seems primarily
caused by a tendency to avoid negative consequences (Smits et al., 2004).
Anger-in refers to inhibition of aggression, whereas anger-out refers to overt
aggressive behaviour. Anger-control refers to the ability to modulate emotional
and behavioural expression of anger. These categories are usually assessed by
subjective self-report measures such as the State-Trait Anger Expression
Inventory, or STAXI (Spielberger, 1988). Recently developed questionnaires show
more diversity of anger coping strategies and pay more attention to the context
of daily life and interpersonal relationships, including gender differences
(Trnka & Stuchlíková, 2011). Despite adaptations, self-report measures remain
limited by response biases (Bartz, Blume & Rose, 1996). Additional
performance-based measures are needed to estimate behavioural and non-verbal
aspects of anger. Observational methods in laboratory or real-life situations
may be a next step towards ecologically valid measurement of anger coping,
taking into account that a negative observer bias may interrupt natural anger
expressions.

In this study a performance-based psychomotor measuring instrument of
aggression regulation is developed for clinical and research purposes and
tested on its psychometric quality. This instrument is called the *Method of
Stamp Strike Shout* (MSSS) and will be developed to be applied in addition to
self-report scales. Recorded are the impulses of hitting a punching bag,
stamping on a force plate, and shouting in a microphone. The MSSS offers the
opportunity to observe the body in action and to combine quantitative outcome
measures with qualitative observation and post-test interview. Goal of the MSSS
is to provide patient and therapist with feedback on body performance for
diagnostic as well as treatment purposes, targeted on learning to apply
expressive movement and controlled force production as a vehicle for aggression
regulation. Development of the MSSS is part of a larger research on the effect
of psychomotor therapy and aggression regulation on patients with eating
disorders ( METTIG nr. 9215 / CCMO nr. NL28665.097.09).

The MSSS was tested in an explorative study in corporation with the Center of
Human Movement Sciences, University of Groningen. The data on 100 healthy
participants (students) have been analysed, that will be used as a reference
(Boerhout et al., 2018a, accepted by PLOS ONE). Scores on maximum force
production and control over increasing and decreasing force were linked to a
self-report measure on anger-in, anger-out, and anger-control, namely the
Self-Expression and Control Scale (SECS, Van Elderen et al., 1997), a Dutch
translation of the Anger Expression Scale which is part of the STAXI
(Spielberger, 1988). In the proposed study this same procedure will be applied
with 50 patients with eating disorders who are invited to voluntarily
participate in a MSSS session.

Participation in a MSSS session takes around 30 minutes. Besides three short
questionnaires, a short instruction and physical warming-up is given and
participants are asked to stamp on a force plate, strike with boxing gloves on
a punching bag and shout in a microphone with increasing and decreasing force.
It is very unlikely and has not been observed in earlier clinical and research
situations that using the well-structured protocol of the MSSS increases the
risk of injury or los of control over emotions. We don*t expect any adverse
events to happen and for this reason no risks are associated with
participation.