Basic research in "aggression"
- From: "whitesickle@xxxxxxx" <whitesickle@xxxxxxx>
- Date: Fri, 17 Feb 2006 13:52:37 -0500 (EST)
Some suggestions for revitalizing
aggression research
Robert J. Blanchard and D. Caroline Blanchard*1
Department of Psychology, University of Hawaii, 2430 Campus Road,
Honolulu, HI 96822,
and Pacific Biomedical Research Center, University of Hawaii, 1993 East
West Road
Honolulu, HI 96822, USA
Abstract. Aggression research is moribund. Lack of research over the
past two decades
has left many issues. (1) Understanding varieties of agonistic
behaviour in an ethological
context: categories differring in behaviours, target sites and function
include offence,
defensive attack, and predation. Biological systems must be determined
for each of
these. (2) Insuring availability of ethologically valid laboratory
models of agonistic
behaviour and describing (possibly species-specfic) standards for
these. We shall
present models and consider the problematic issue of biting. (3) Use of
non-damaging
behavioural markers that precede fights. These should be independently
analysed,
measured and verified as potential substitutes for biting attack. (4)
Interaction between
fear and offensive aggressive motivation systems must be understood in
order to evaluate
whether independent variable (e.g. pharmacological, genetic) effects
involve a specific
motivational system rather than reflecting changes in oppositional
systems. (5)
Knowledge of agonistic systems and their biological basis must be
extended to humans,
focusing on both normal aggression in each category, and the
development of models of
aggressive psychopathology. Placing aggression research in an
ethological context and
focusing on its biomedical relevance may help to counter forces
suppressing this work.
2005 Molecular mechanisms influencing aggressive behaviours. Wiley,
Chichester (Novartis
Foundation Symposium 268) p 419
Basic research in aggression: a dying field?
It is a considerable irony that during the past 30 years, a period in
which problems
of interpersonal and group violence in real world settings have come
more and
more strongly to the attention of the public and the media, the
relative attention
of the scientific community to basic experimental research on
aggression has
sharply declined. This statement is based on data for research on the
three rodent
species that are used as subjects of most experimental aggression
experiments:
PubMed citations appearing in response to the search terms
'aggressive
behaviour' and 'rat' (or mouse, or hamster) during three year
periods from 1970
to 2000 indicate that citations for rats and mice are about equal, and
appear to reflect
a peak in the early 1970s followed by a slow decline. Hamster studies,
fewer in
number, remained relatively steady over this period.
In contrast to this steady state, comparable figures for studies of
sexual and
stress-related behaviour for the same three species of laboratory
animals indicate
a sharply increasing trend over the same period. Although both areas
received
attention comparable to that of aggression research in 1970, studies of
sexual
behaviour have since almost tripled, and stress-related behaviour
increased nearly
20 times. Thus, on a baseline of activity in comparable areas of
behavioural
research, it can be seen that aggression research has substantially
declined over
the past 30 years. The comparison with stress research is particularly
interesting,
as increased restrictions on animal research involving aversive events
might be
blamed for the decline in experimental aggression work. However, the
striking
increase in rodent research on stress indicates that, although
restrictions on
animal research may have exerted considerable inhibitory influence
overall, they
do not appear to have served as a specific and differential inhibitor
of work
involving response to stressful or provocative conditions.
Finally, while the absolute numbers of aggression studies involved may
seem
adequate even if sufferring in comparison to other areas, these numbers
provide
an overestimation of the magnitude of true aggression research.
Individual
analysis of citations for a single year (2000) indicated that only
about 24% of the
studies retrieved by this searchsome 36 studies for the year
2000contributed
directly and empirically to our knowledge of o¡ensive aggressive
behaviour in the
three laboratory species in which it has been best and most thoroughly
analysed.
What is aggression, and why should it be studied?
Aggression is something of a 'catch-all' term for several types of
evolved
behaviours (Blanchard et al 1999). Like other evolved behaviour
patterns, these
behaviours are adaptive under a range of circumstances, but may be
maladaptive
in other situations. Analogously, evolved appetites for fats and sugars
are adaptive
when these nutrients are in relatively short or sporadic supply, but
may result in
widespread obesity and other health problems when such food items are
abundant.
Evolved behaviours also involve underlying brain and neurochemical
systems,
and additional problems may occur when these are hyperexpressed,
resulting in
pathological manifestation of behaviour; too much, too poorly
controlled, or in
the wrong situation (Marks&Nesse 1994). As will be detailed later, one
variety of
aggressionoffensive aggressionis particularly sensitive to its own
consequences, in the form of behaviour change on the part of the
opponent. This
sets up conditions for it to serve as an operant; offensive aggression
increases when
it is reinforced, leading directly to functions that are sometimes
grouped under the
rubric 'instrumental aggression' and providing for another avenue
by which
aggressive behaviour can become problematic. Finally, there is the
problem of
group aggression. This is a relatively rare phenomenon in other
mammalian
species, showing, however, a clear increase in larger-brained primates
and
reaching extraordinarily high levels in people. In combination with
other factors
such as the sensitivity of offensive aggression to successful
consequences, and
technological enhancement of the capacity of aggressive behaviour to
cause
damage, group aggression has been a prominent problem throughout human
history (Keeley 1996).
This problem, that hyperexpressed and damaging aggression is common in
human societies, constitutes one important reason for studying
aggressive
behaviour. The second is simply that aggression, even when normal and
adaptive, includes several deeply interesting examples of evolved
behaviour
patterns that are simultaneously highly responsive to antecedent
circumstances
and to their own consequences. These patterns may be common across
mammalian species, but there are important differences from one species
to
another in when, how, and to what effect the various types of
aggression are
expressed. All varieties of aggression known in inframammalian species
are
found in people, and the brain systems and behavioural budgets of both
human
and non-human mammals devote an extraordinary amount of space or time
to
them. They are worthy of study.
.
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