Anxiety-induced cognitive bias in non-human animals.
ABSTRACT As in humans, 'cognitive biases' in the way in which animals judge ambiguous stimuli may be influenced by emotional state and hence a valuable new indicator of animal emotion. There is increasing evidence that animals experiencing different emotional states following exposure to long-term environmental manipulations show contrasting biases in their judgement of ambiguous stimuli. However, the specific type of induced emotional state is usually unknown. We investigated whether a short-term manipulation of emotional state has a similar effect on cognitive bias, using changes in light intensity; a treatment specifically related to anxiety-induction. Twenty-four male rats were trained to discriminate between two different locations, in either high ('H') or low ('L') light levels. One location was rewarded with palatable food and the other with aversive food. Once the rats had shown spatial discrimination, by running significantly faster to the rewarded location, they were tested with three ambiguous locations intermediate between the rewarded and aversive locations, and their latency to approach each location recorded. Half the rats were tested in the same light levels as during training, the remainder were switched. Rats switched from high to low light levels (putatively the least negative emotional manipulation) ran significantly faster to all three ambiguous probes than those rats switched from low to high light levels (putatively the most negative manipulation). This suggests that the judgement bias technique might be useful as an indicator of short-term changes in anxiety for non-human animals.
SourceAvailable from: Alan G. McElligott[Show abstract] [Hide abstract]
ABSTRACT: REVIEW paper. The development of accurate measures of animal emotions is important for improving and promoting animal welfare. Cognitive bias indicates the effect of emotional states on cognitive processes, such as memory, attention, and judgement. Cognitive bias tests complement existing behavioural and physiological measures for assessing the valence of animal emotions indirectly. The judgement bias test has been used to assess emotional states in non-human animals; mainly in laboratory settings. The aim of this review is to summarise the findings on the use of the judgement bias test approach in assessing emotions in non-human animals, focussing in particular on farm livestock. The evidence suggests that it is possible to manipulate affective states and induce judgement bias effects in farm livestock. In addition, the results support the effectiveness of manipulating environmental variables for inducing negative or positive affective states. However, the evidence from farm livestock does not consistently confirm the directionality of the hypotheses. The use of specific strategies to induce positive or negative judgement bias, such as the manipulation of housing conditions, could account for the inconsistency of findings. The study of cognitive processes related to emotional states in livestock has great potential to advance and improve our understanding of animal welfare.Animal welfare (South Mimms, England) 02/2015; 24:81-91. DOI:10.7120/09627286.24.1.081 · 1.23 Impact Factor
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ABSTRACT: Normal anxiety is considered an adaptive response to the possible presence of danger, but it appears highly susceptible to dysregulation. Anxiety disorders are prevalent at high frequency in contemporary human societies, yet impose substantial disability upon their sufferers. This raises a puzzle: why has evolution left us vulnerable to anxiety disorders? We develop a signal detection model in which individuals must learn how to calibrate their anxiety responses: they need to learn which cues indicate danger in the environment. We study the optimal strategy for doing so, and find that individuals face an inevitable exploration-exploitation tradeoff between obtaining a better estimate of the level of risk on one hand, and maximizing current payoffs on the other. Because of this tradeoff, a subset of the population becomes trapped in a state of excessive and self-perpetuating anxiety, even when individuals learn optimally. This phenomenon arises because when individuals become too cautious, they stop sampling the environment and fail to correct their misperceptions, whereas when individuals become too careless they continue to sample the environment and soon discover their mistakes. We suggest that this process may be involved in the development of excessive anxiety in humans.
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ABSTRACT: Recent advances in animal welfare science used judgement bias, a type of cognitive bias, as a means to objectively measure an animal's affective state. It is postulated that animals showing heightened expectation of positive outcomes may be categorised optimistic, while those showing heightened expectations of negative outcomes may be considered pessimistic. This study pioneers the use of a portable, automated apparatus to train and test the judgement bias of dogs. Dogs were trained in a discrimination task in which they learned to touch a target after a tone associated with a lactose-free milk reward and abstain from touching the target after a tone associated with water. Their judgement bias was then probed by presenting tones between those learned in the discrimination task and measuring their latency to respond by touching the target. A Cox's Proportional Hazards model was used to analyse censored response latency data. Dog and Cue both had a highly significant effect on latency and risk of touching a target. This indicates that judgement bias both exists in dogs and differs between dogs. Test number also had a significant effect, indicating that dogs were less likely to touch the target over successive tests. Detailed examination of the response latencies revealed tipping points where average latency increased by 100% or more, giving an indication of where dogs began to treat ambiguous cues as predicting more negative outcomes than positive ones. Variability scores were calculated to provide an index of optimism using average latency and standard deviation at cues after the tipping point. The use of a mathematical approach to assessing judgement bias data in animal studies offers a more detailed interpretation than traditional statistical analyses. This study provides proof of concept for the use of an automated apparatus for measuring cognitive bias in dogs.PLoS ONE 09/2014; 9(9):e107794. DOI:10.1371/journal.pone.0107794 · 3.53 Impact Factor