Fear and Fearfulness in Animals

Abstract

Persistence of individual differences in animal behavior in reactions to various environmental challenges could reflect basic divergences in temperament, which might be used to predict details of adaptive response. Although studies have been carried out on fear and anxiety in various species, including laboratory, domestic and wild animals, no consistent definition of fearfulness as a basic trait of temperament has emerged. After a classification of the events that may produce a state of fear, this article describes the great variability in behavior and in physiological patterns generally associated with emotional reactivity. The difficulties of proposing fearfulness--the general capacity to react to a variety of potentially threatening situations--as a valid basic internal variable are then discussed. Although there are many studies showing covariation among the psychobiological responses to different environmental challenges, other studies find no such correlations and raise doubts about the interpretation of fearfulness as a basic personality trait. After a critical assessment of methodologies used in fear and anxiety studies, it is suggested that discrepancies among results are mainly due to the modulation of emotional responses in animals, which depend on numerous genetic and epigenetic factors. It is difficult to compare results obtained by different methods from animals reared under various conditions and with different genetic origins. The concept of fearfulness as an inner trait is best supported by two kinds of investigations. First, an experimental approach combining ethology and experimental psychology produces undeniable indicators of emotional reactivity. Second, genetic lines selected for psychobiological traits prove useful in establishing relationships between behavioral and neuroendocrine aspects of emotional reactivity. It is suggested that fearfulness could be considered a basic feature of the temperament of each individual, one that predisposes it to respond similarly to a variety of potentially alarming challenges, but is nevertheless continually modulated during development by the interaction of genetic traits of reactivity with environmental factors, particularly in the juvenile period. Such interaction may explain much of the interindividual variability observed in adaptive responses.

Temperament, age and weather predict social interaction in the sheep flock

“…Behaviour in the IBT reflects temperament and in this context vocalisations are reflective of fear in isolation, and a desire to re-establish social contact (Boissy 1995;Boissy et al 2005). Vocalisations are used by sheep to locate and recognise conspecifics (Dwyer and Lawrence 2008), but in the current study contact was not associated with frequency of vocalisations, as according to the MMMC model the more vocal sheep did not necessarily spend more time with all sheep.…”

Relationship between the behaviour of sows at 6 months old and the behaviour and performance at farrowing

“…This correlation is not easy to interpret. Generally, the novel object test is used to test general fearfulness, those interacting quickly with the object being less fearful (Boissy, 1995). It could be that those interacting quickly with the object are more active animals.…”

Long-term exposure to unpredictable and uncontrollable aversive events alters fearfulness in sheep

“…Emotional reactions of animals can be inferred from acute physiological and behavioural adjustments, such as increased heart rate, elevated blood corticoid levels and specific behaviours in response to potential alarming events. Boissy (1998) proposed the term 'fearfulness' as a temperamental trait characterizing the propensity of an individual to be frightened by a variety of alarming events, and which depends on the individual's own evaluation of the situation.…”