If a baby macaque monkey must be separated from its mother, it should be pre-fed formula
before separation at around day 5-6. If a milk bottle is always present and the infant always
lifted to the bottle to feed, it will learn to feed itself in about 30 hours. Peer contact before
the age of 5 months is desirable and as little as 1 hour per day produces socially adequate
monkeys. A peer, adult male, unrelated adult female, or older juvenile can be used as a
mother-substitute but if a peer is used, excessive clinging results from continuous contact
with the same peer(s) and excessive aggression results if contact is with only one other
animal. Self-injurious behaviour (similar to human stereotypy and not human SIB) results
when young monkeys cannot direct aggressive play towards another monkey because one is
not present during the day when the appropriate direction for such behaviour is practised. If
the young monkey is subjected to higher or lower levels of aggression, their subsequent level
of aggressiveness will be similarly changed, even when there is no opportunity for modelling.
It is as ifthere is some mechanism for copying those levels of aggression to which they are
subjected. During therapy of isolates, infants keep aggression levels low. Aggression levels
are also determined by visual stimuli, animals that can never see other animals showing no
aggression and those intermittently viewing them showing lower levels when interacting with
others in total darkness. Interference with visual interaction by foliage or screens also
reduces aggression by at least half in farmed animals such as bulls, deer, and chickens.
Personality, as determined by traditional factor-analytic techniques, is less able to
predict behaviour in macaques than dominance rank. High dominance rank protects animals
during fights from stress, while large changes in rank are stressful in new groupings. Most
groups have individuals with specific roles independent from but influenced by dominance
rank, and when those members are absent, group behaviour is not as efficient. Attachment
bonds influence protective harassment during post-mating ties and attachment is more
influenced by early companionship than by kinship or type of rearing.
To improve housing conditions for non-human primates, a litter-like substrate is
more hygienic than bare floors cleaned twice daily. It allows foraging which reduces
aggression and is performed even when the same food is freely available. Food-related tasks
are best at simulating patterns of wild behaviour although brief periods of challenge are also
beneficial. Visitors to zoos provide long-term stress which can be reduced if humans are
located at a level lower than the monkeys. Behaviours of activity, grooming, aggression and
abnormal differentiate long-term stress from enrichment. Enrichment may be conceptualised
as increasing psychological space in that the animals must do more to get achieve less. Some
enrichment devices are rarely used such as ropes unless they are more unpredictable.
Humans too, especially those in institutions, benefit from physical and mental
activity reporting that they feel better, are seen to interact healthier and more with others, and
are rated as improved by nursing staff. Benefits of occupational therapy may be attributed
simply to increasing activity. Like in monkeys, many of the objects supplied to
institutionalised people are rarely used; personal items are used more frequently.
Encouraging people with a mental handicap to change their behaviour is often less effective
than "paradoxical prescriptions;" encouraging undesirable behaviour can dramatically reduce
Monkeys with a mental handicap similar to human phenylketonuria, show abnormal
learning and social behaviour which can be characterised as excessive emotionality. When
with other monkeys they react with high levels of aggression and fear in normal hierarchical
situations which reduces play; when making an error in learning tasks they are excessively
rigid in subsequent trials leading to high error rate, poor adaptation, and inferior learning.
Increasing relative success and redundancy is likely to counteract some effects of such
retardation. Fewer monkeys may be used in such studies if sequential sampling techniques
are used, especially if a measure of effect size can be estimated.